Publications by authors named "Xiping Deng"

39 Publications

Liquor Flavour Is Associated With the Physicochemical Property and Microbial Diversity of Fermented Grains in Waxy and Non-waxy Sorghum () During Fermentation.

Front Microbiol 2021 17;12:618458. Epub 2021 Jun 17.

College of Agronomy, State Key Laboratory of Crop Stress Biology in Arid Areas/Northwest A&F University, Yangling, China.

The fermentation process of Chinese Xifeng liquor involves numerous microbes. However, the sources of microbes in fermented grain and the link between liquor flavour and physicochemical properties and microbial diversity during fermentation still remain unknown. Herein, two waxy (JiNiang 2 [JN-2] and JinNuo 3 [JN-3]) and four non-waxy (JiZa 127 [JZ-127], JinZa 34 [JZ-34], LiaoZa 19 [LZ-19], and JiaXian [JX]) sorghum varieties were selected for the comprehensive analysis of the relationship between liquor flavour and the physicochemical properties and microbial diversity of fermented grains. Results showed that ethyl acetate was the main flavour component of JZ-127, JZ-34, and JX, whereas ethyl lactate was mainly detected in JN-2, JN-3, and LZ-19. Ethyl lactate accounted for half of the ethyl acetate content, and JX exhibited a higher liquor yield than the other sorghum varieties. The fermented grains of waxy sorghum presented higher temperature and reducing sugar contents but lower moisture and starch contents than their non-waxy counterparts during fermentation. We selected JN-3 and JX sorghum varieties to further investigate the microbial changes in the fermented grains. The bacterial diversity gradually reduced, whereas the fungal diversity showed nearly no change in either JN-3 or JX. was the most abundant bacterial genus, and its level rapidly increased during fermentation. The abundance of accounted for the total proportion of bacteria in JX, and it was higher than that in JN-3. was the most abundant fungal genus in JX, but its abundance accounted for a small proportion of fungi in JN-3. Four esters and five alcohols were significantly positively related to Proteobacteria, Bacteroidetes, and Actinobacteria; Alphaproteobacteria, Actinobacteria, and Bacteroidia; Bacillales, Bacteroidales, and Rhodospirillales; and , , and . This positive relation is in contrast with that observed for Firmicutes, Bacilli, Lactobacillales, and . Meanwhile, was the only fungal microorganism that showed a significantly negative relation with such compounds (except for butanol and isopentanol). These findings will help in understanding the fermentation mechanism and flavour formation of fermented Xifeng liquor.
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http://dx.doi.org/10.3389/fmicb.2021.618458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8247930PMC
June 2021

Physiological and Differential Proteomic Analyses of Imitation Drought Stress Response in Root at the Seedling Stage.

Int J Mol Sci 2020 Dec 1;21(23). Epub 2020 Dec 1.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources Section, Xianyang 712100, China.

Drought is one of the most important constraints on the growth and productivity of many crops, including sorghum. However, as a primary sensing organ, the plant root response to drought has not been well documented at the proteomic level. In the present study, we compared physiological alteration and differential accumulation of proteins in the roots of sorghum () inbred line BT×623 response to Polyethylene Glycol (PEG)-induced drought stress at the seedling stage. Drought stress (up to 24 h after PEG treatment) resulted in increased accumulation of reactive oxygen species (ROS) and subsequent lipid peroxidation. The proline content was increased in drought-stressed plants. The physiological mechanism of sorghum root response to drought was attributed to the elimination of harmful free radicals and to the alleviation of oxidative stress via the synergistic action of antioxidant enzymes, such as superoxide dismutase, peroxidase, and polyphenol oxidase. The high-resolution proteome map demonstrated significant variations in about 65 protein spots detected on Coomassie Brilliant Blue-stained 2-DE gels. Of these, 52 protein spots were identified by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF-TOF MS) representing 49 unique proteins; the levels of 43 protein spots were increased, and 22 were decreased under drought condition. The proteins identified in this study are involved in a variety of cellular functions, including carbohydrate and energy metabolism, antioxidant and defense response, protein synthesis/processing/degradation, transcriptional regulation, amino acid biosynthesis, and nitrogen metabolism, which contribute jointly to the molecular mechanism of outstanding drought tolerance in sorghum plants. Analysis of protein expression patterns and physiological analysis revealed that proteins associated with changes in energy usage; osmotic adjustment; ROS scavenging; and protein synthesis, processing, and proteolysis play important roles in maintaining root growth under drought stress. This study provides new insight for better understanding of the molecular basis of drought stress responses, aiming to improve plant drought tolerance for enhanced yield.
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http://dx.doi.org/10.3390/ijms21239174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7729455PMC
December 2020

Comprehensive evaluation of physiological traits under nitrogen stress and participation of linolenic acid in nitrogen-deficiency response in wheat seedlings.

BMC Plant Biol 2020 Nov 3;20(1):501. Epub 2020 Nov 3.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, 712100, Shaanxi, China.

Background: Nitrogen (N) deficiency is a major constraint for plant production in many areas. Developing the new crop genotypes with high productivity under N deficiency is an important approach to maintain agricultural production. Therefore, understanding how plant response to N deficiency and the mechanism of N-deficiency tolerance are very important for sustainable development of modern crop production.

Results: In this study, the physiological responses and fatty acid composition were investigated in 24 wheat cultivars under N-deficient stress. Through Pearson's correlation analysis and principal component analysis, the responses of 24 wheat cultivars were evaluated. The results showed that the plant growth and carbohydrate metabolism were all differently affected by N deficiency in all tested wheat cultivars. The seedlings that had high shoot biomass also maintained high level of chlorophyll content under N deficiency. Moreover, the changes in fatty acid composition, especially the linolenic acid (18:3) and the double bond index (DBI), showed close positive correlations with the shoot dry weight and chlorophyll content alterations in response to N-deficient condition. These results indicated that beside the chlorophyll content, the linolenic acid content and DBI may also contribute to N-deficiency adaptation, thus could be considered as efficient indicators for evaluation of different response in wheat seedlings under N-deficient condition.

Conclusions: The alteration in fatty acid composition can potentially contribute to N-deficiency tolerance in plants, and the regulation of fatty acid compositions maybe an effective strategy for plants to adapt to N-deficient stress.
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http://dx.doi.org/10.1186/s12870-020-02717-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7607636PMC
November 2020

Arabidopsis mgd mutants with reduced monogalactosyldiacylglycerol contents are hypersensitive to aluminium stress.

Ecotoxicol Environ Saf 2020 Oct 21;203:110999. Epub 2020 Jul 21.

State Key Laboratory of Crop Stress Biology in Arid Areas/College of Agronomy, Northwest A & F University, Yangling, Shaanxi, 712100, PR China. Electronic address:

Aluminium (Al) is a key element that plays a major role in inhibiting plant growth and productivity under acidic soils. While lipids may be involved in plant tolerance/sensitivity to Al, the role of monogalactosyldiacylglycerol (MGDG) in Al response remains unknown. In this study, Arabidopsis MGDG synthase (AtMGD) mutants (mgd1, mgd2 and mgd3) and wild-type (Col-0) plants were treated with AlCl; the effect of aluminium on root growth, aluminium distribution, plasma membrane integrity, lipid peroxidation, hydrogen peroxide content and membrane lipid compositions were analysed. Under Al stress, mgd mutants exhibited a more severe root growth inhibition, plasma membrane integrity damage and lipid peroxidation compared to Col-0. Al accumulation in root tips showed no difference between Col-0 and mutants under Al stress. Lipid analysis demonstrated that under Al treatment the MGDG content in all plants and MGDG/DGDG (digalactosyldiacylglycerol) remarkably reduced, especially in mutants impairing the stability and permeability of the plasma membrane. These results indicate that the Arabidopsis mgd mutants are hypersensitive to Al stress due to the reduction in MGDG content, and this is of great significance in the discovery of effective measures for plants to inhibit aluminium toxicity.
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http://dx.doi.org/10.1016/j.ecoenv.2020.110999DOI Listing
October 2020

Plastic mulching reduces nitrogen footprint of food crops in China: A meta-analysis.

Sci Total Environ 2020 Dec 6;748:141479. Epub 2020 Aug 6.

Gansu Provincial Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, China; College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China. Electronic address:

Sustainably feeding the growing population amid rising global temperatures and dwindling resources is a grand challenge facing mankind. Plastic mulching (PM) is widely used in China aiming to the increase of crop productivity. However, the impact of PM on reactive nitrogen (Nr) emissions and nitrogen (N) footprint has not been explicitly described. In this study, we collected 4051 observations from 394 published papers for potato (Solanum tuberosum L.), maize (Zea mays L.), and wheat (Triticum aestivum L.), and used meta-analysis to investigate how PM affected crop yield, net economic return, Nr emissions, and N footprints including nitrogen footprint per unit of output energy (NFo) and nitrogen footprint per unit of net economic return (NFe) at regional scale and across a range of precipitation and N fertilization gradients in China. The meta-analysis showed that compared to non-PM practice, PM increased grain yield by 25, 27, and 20% in potato, maize, and wheat, respectively, and enhanced net economic return by 19, 29, and 22%, respectively, with corresponding reduction in NFo of 24, 36, and 18% and NFe of 19, 37, and 19%, respectively. Potato and maize had greater energy output and net economic return than wheat. Plastic mulching was more effective in improving net economic return (or energy output) and reducing N footprints (i.e., NFe and NFo) in the semiarid region (i.e., annual precipitation <600 mm) when N was applied at 100-200 kg N ha, especially in potato and maize. Our analysis suggests that the use of PM enhanced grain yield and net economic return while lowering the N footprint without increasing Nr emission. Therefore, PM has great potential to mitigate Nr loss in China when crop species, N fertilization rate, and local environmental factors (i.e., growing region and annual precipitation) are appropriately considered.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141479DOI Listing
December 2020

Exogenous melatonin alleviates PEG-induced short-term water deficiency in maize by increasing hydraulic conductance.

BMC Plant Biol 2020 May 14;20(1):218. Epub 2020 May 14.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, 712100, Shaanxi, China.

Background: Water deficiency is likely to become more frequent and intense as a result of global climate change, which may severely impact agricultural production in the world. The positive effects of melatonin (MEL) on alleviation drought or osmotic stress-induced water deficiency in plants has been well reported. However, the underlying mechanism of MEL on the detailed process of plant water uptake and transport under water deficiency condition remains largely unknown.

Results: Application of 1 μM MEL led to enhanced tolerance to water deficiency stress in maize seedlings, as evidenced by maintaining the higher photosynthetic parameters, leaf water status and plant transpiration rate. The relatively higher whole-plant hydraulic conductance (K) and root hydraulic conductance (Lp) in MEL-treated seedlings suggest that exogenous MEL alleviated water deficiency stress by promoting root water absorption. HgCl (aquaporin inhibitor) treatment inhibit the transpiration rate in MEL-treated plants greater than those of MEL-untreated; after recovery by dithiothreitol (DTT, anti-inhibitor), the transpiration rate in MEL-treated plants increased much higher than those of untreated plants. Moreover, under water deficiency, the transcription level of aquaporin genes was up-regulated by MEL application, and the HO was less accumulated in MEL-treated root.

Conclusions: Exogenous MEL promoted aquaporin activity, which contributed to the maintaining of Lp and K under short-term water deficiency. The increased water uptake and transport lead to improved water status and thus increased tolerance to PEG-induced short-term water deficiency in maize seedlings.
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http://dx.doi.org/10.1186/s12870-020-02432-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227339PMC
May 2020

Combined application of silicon and nitric oxide jointly alleviated cadmium accumulation and toxicity in maize.

J Hazard Mater 2020 Aug 13;395:122679. Epub 2020 Apr 13.

Henan Key Laboratory for Molecular Ecology and Germplasm Innovation of Cotton and Wheat/Henan Collaborative Innovation Center of Modern Biological Breeding, Henan Institute of Science and Technology, Xinxiang, Henan, 453003, China. Electronic address:

Cadmium (Cd) contamination is a serious threat to plants and humans. Application of silicon (Si) or nitric oxide (NO) could alleviate Cd accumulation and toxicity in plants, but whether they have joint effects on alleviating of Cd accumulation and toxicity are not known. Therefore, the combined effect of Si and NO application on maize growth, Cd uptake, Cd transports and Cd accumulation were investigated in a pot experiment. Here, we reported that Cd stress decreased growth, caused Cd accumulation in plants. The combined application of Si and NO triggered a significant response in maize, increasing plant growth and reducing Cd uptake, accumulation, translocation and bioaccumulation factors under Cd stress. The grain Cd concentration was decreased by 66 % in the Si and NO combined treatment than Cd treatment. Moreover, the combined application of Si and NO reduced Cd health risk index in maize more effectively than either treatment alone. This study provided new evidence that Si and NO have a strong joint effect on alleviating the adverse effects of Cd toxicity by decreasing Cd uptake and accumulation. We advocate for supplement of Cd-contaminated soil with Si fertilizers and treatment of crops with NO as a practical approach to alleviating Cd toxicity.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122679DOI Listing
August 2020

Low-nitrogen tolerance comprehensive evaluation and physiological response to nitrogen stress in broomcorn millet (Panicum miliaceum L.) seedling.

Plant Physiol Biochem 2020 Jun 23;151:233-242. Epub 2020 Mar 23.

State Key Laboratory of Crop Stress Biology in Arid Areas/Shaanxi Research Station of Crop Gene Resources & Germplasm Enhancement, Ministry of Agriculture, College of Agronomy, Northwest A & F University, Yangling, Shaanxi, 712100, PR China. Electronic address:

Developing the new crop varieties with high productivity under low nitrogen (N) input is an important access to facilitate modern agricultural sustainability. In the present study, 20 broomcorn millet (Panicum miliaceum L.) varieties were characterized for their morphological and nutrient parameters to different low N levels in seedling. The results showed that 0.25 mM NHNO was the standard concentration for the evaluation and identification of low-N tolerance. Through pearson's correlation analysis, principal component analysis, and subordinate function analysis, the tolerance of 20 varieties under N stress was evaluated and plant height, root length, shoot biomass, and shoot and root N content were considered as the evaluation system of low-N tolerance. Although leaves photosynthetic capacities and activities of N metabolism related enzymes showed the decreasing tendency to N stress, low-N tolerant varieties had higher activities in both leaves and roots as compared to low-N sensitive varieties. The work provides a reliable and comprehensive method for evaluating low-N tolerance in broomcorn millet and our data elucidate possible physiological adaptive mechanisms by which broomcorn millet tolerates N stress.
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http://dx.doi.org/10.1016/j.plaphy.2020.03.027DOI Listing
June 2020

Linkages between nutrient ratio and the microbial community in rhizosphere soil following fertilizer management.

Environ Res 2020 05 17;184:109261. Epub 2020 Feb 17.

College of Agronomy, State Key Laboratory of Crop Stress Biology in Arid Areas/Northwest A & F University, Yangling, Shaanxi, 712100, PR China; Shaanxi Research Station of Crop Gene Resources & Germplasm Enhancement, Ministry of Agriculture, Yangling, Shaanxi, 712100, PR China. Electronic address:

To unravel the linkages between ecological ratios (C:N:P) and the microbial community in rhizosphere soil in response to fertilizer management, soil samples were collected from a proso millet (Panicum miliaceum L.) field under different fertilizer management systems, including nitrogen fertilizer (NF), phosphorus fertilizer (PF), combined N and P (NP) fertilizer, and organic fertilizer (OF); no fertilizer (CK) was used as a control. Furthermore, 16S rRNA and ITS gene sequencing were applied to represent the bacterial and fungal diversity in the soil. Moreover, the elemental properties, including the carbon (C), nitrogen (N), and phosphorus (P) contents, in the microbial biomass and rhizosphere soil were evaluated. The results showed that the C, N, and P contents and microbial biomass (MBC, MBN and MBP, respectively) in the rhizosphere soil were augmented following fertilizer management. Increases in the alpha diversity indices (Shannon and Chao 1) of soil bacteria and fungi were observed in response to the fertilizers, and the responses were more closely related to the soil C:N and N:P ratios than to the C:P ratio. Additionally, with high relative abundances (>1%) across all soil samples, the composition of soil microbial phyla levels revealed different trends following fertilizer management. The abundances of Actinobacteria and Gemmatimonadetes increased, while the abundances of Acidobacteria and Nitrospirae decreased (P < 0.05) following fertilizer management. Among the fungal taxa, the abundances of Ascomycota and Mortierellomycota responded positively to fertilizer. These results were largely influenced by changes in the C:N and N:P ratios in both the soil and microbial biomass. Overall, significantly increased C:N and decreased N:P ratios in the soil reflected the N deficiency that would limit increased microbial biomass and diversity. Together, all of these results indicated that interactions between ecological ratios (C:N:P) and microbial community composition play vital roles in resource imbalance in dynamic environments. Thus, N status should be an important factor for sustainable agricultural management. Moreover, the synergistic effects were better with the combination of C, N, and P or with organic fertilizer than with C, N and P separately.
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http://dx.doi.org/10.1016/j.envres.2020.109261DOI Listing
May 2020

Melatonin promotes plant growth by increasing nitrogen uptake and assimilation under nitrogen deficient condition in winter wheat.

Plant Physiol Biochem 2019 Jun 29;139:342-349. Epub 2019 Mar 29.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi, 712100, China; College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi, 712100, China. Electronic address:

Melatonin (MEL) has been widely reported to be beneficial to plant growth and development, but few studies have combined investigations of the performance and function of MEL with detailed physiologically based analyses of nitrogen (N) uptake and metabolism in staple crops. In this study, the effect of MEL application on winter wheat seedling growth and grain yield were investigated in hydroponic and pot experiments at different N levels. The result showed that application of 1 μM MEL in hydroponic solution significantly improved the wheat seedling growth under both N sufficient and deficient conditions, but the effect of MEL on promoting seedling growth was prominent under N deficient condition. Meanwhile, MEL-treated plants maintained higher N contents and nitrate nitrogen levels in shoot under N deficient condition, and also maintained higher nitrate nitrogen levels in root. Further investigation showed that nitrate reductase (NR) and glutamine synthetase (GS) activities were higher in MEL-treated plants than that of MEL-untreated plants under N deficiency. The N absorption calculated based on N contents and biomass showed that MEL could promote the N absorption under N deficient condition. In pot experiment, pre-soaking of seeds with 100 μM MEL enhanced per-plant yield by 16% under N sufficient condition and 23% under N deficient condition. Taken together, the results of this study indicate that MEL is involved in promoting N uptake and assimilation through up-regulating the activities of N uptake and metabolism related enzymes and, ultimately, promotes the plant growth and yield, especially under N deficient condition.
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http://dx.doi.org/10.1016/j.plaphy.2019.03.037DOI Listing
June 2019

Down-regulation of lycopene ε-cyclase expression in transgenic sweetpotato plants increases the carotenoid content and tolerance to abiotic stress.

Plant Sci 2019 Apr 10;281:52-60. Epub 2019 Jan 10.

Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Daejeon 34141, Republic of Korea. Electronic address:

Carotenoids are required for many biological processes in plants and humans. Lycopene ε-cyclase (LCY-ε) catalyzes the conversion of lycopene into lutein via the α-branch carotenoid biosynthesis pathway. Down-regulation of IbLCY-ε by RNAi increases carotenoid accumulation and salt stress tolerance in transgenic sweetpotato calli. As the role of IbLCY-ε in carotenoid biosynthesis and environmental stress responses in whole plants is poorly understood, transgenic sweetpotato (RLE plants) with reduced expression of IbLCY-ε were developed. RLE plants contained higher levels of total carotenoid and β-carotene, due to an elevated β-carotene/lutein ratio rather than increased de novo biosynthesis. RLE plants showed high reactive oxygen species/radical-scavenging activity. They also exhibited an enhanced tolerance of both salt and drought stress, which was associated with lower membrane permeability and a higher photosynthetic rate, respectively. Elevated carotenoid accumulation in RLE plants mitigated the reductions in leaf photosystem II efficiency and chlorophyll induced by abiotic stress. Expression of the carotenoid cleavage genes 9-cis-epoxycarotenoid dioxygenase, carotenoid cleavage dioxygenase 1 (CCD1) and CCD4 was higher in RLE plants, as was abscisic acid accumulation. IbLCY-ε silencing thus offers an effective approach for developing sweetpotato plants with increased tolerance to abiotic stress that will grow on global marginal lands with no reduction in nutritional value.
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http://dx.doi.org/10.1016/j.plantsci.2019.01.002DOI Listing
April 2019

Melatonin Mitigates Salt Stress in Wheat Seedlings by Modulating Polyamine Metabolism.

Front Plant Sci 2018 3;9:914. Epub 2018 Jul 3.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loss Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, China.

Melatonin, a small molecular weight indoleamine molecule, is involved in various biological processes and responses to environmental cues in plants. However, its function in abiotic stress response and the underlying mechanisms is less clear. In this study, we investigated the effect of melatonin on wheat seedlings growth under salt stress condition. Exogenous melatonin pretreatment partially mitigated the salt-induced inhibition of whole-plant growth as judged from shoot dry weight, IAA content, leaf photosynthesis rate, maximum photochemistry efficiency of photosystem II, and chlorophyll. The mitigation was also observed in reduced accumulation of HO in melatonin-pretreated wheat seedlings exposed to salt stress. Exogenous melatonin increased endogenous melatonin content by evaluating the levels of transcript, which encodes a key regulatory enzyme in the melatonin biosynthetic pathway. Furthermore, melatonin increased polyamine contents by accelerating the metabolic flow from the precursor amino acids arginine and methionine to polyamines; melatonin also decreased the degradation of salt-induced polyamines. Taken together, these results provide the evidence that melatonin mitigates salt stress mainly through its regulation on polyamine metabolism of wheat seedlings.
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http://dx.doi.org/10.3389/fpls.2018.00914DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6037824PMC
July 2018

How Does Silicon Mediate Plant Water Uptake and Loss Under Water Deficiency?

Front Plant Sci 2018 5;9:281. Epub 2018 Mar 5.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, China.

In plants, water deficiency can result from a deficit of water from the soil, an obstacle to the uptake of water or the excess water loss; in these cases, the similar consequence is the limitation of plant growth and crop yield. Silicon (Si) has been widely reported to alleviate the plant water status and water balance under variant stress conditions in both monocot and dicot plants, especially under drought and salt stresses. However, the underlying mechanism is unclear. In addition to the regulation of leaf transpiration, recently, Si application was found to be involved in the adjustment of root hydraulic conductance by up-regulating aquaporin gene expression and concentrating K in the xylem sap. Therefore, this review discusses the potential effects of Si on both leaf transpiration and root water absorption, especially focusing on how Si modulates the root hydraulic conductance. A growing number of studies support the conclusion that Si application improves plant water status by increasing root water uptake, rather than by decreasing their water loss under conditions of water deficiency. The enhancement of plant water uptake by Si is achievable through the activation of osmotic adjustment, improving aquaporin activity and increasing the root/shoot ratio. The underlying mechanisms of the Si on improving plant water uptake under water deficiency conditions are discussed.
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http://dx.doi.org/10.3389/fpls.2018.00281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5844968PMC
March 2018

Pursuing sustainable productivity with millions of smallholder farmers.

Nature 2018 03 7;555(7696):363-366. Epub 2018 Mar 7.

Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China.

Sustainably feeding a growing population is a grand challenge, and one that is particularly difficult in regions that are dominated by smallholder farming. Despite local successes, mobilizing vast smallholder communities with science- and evidence-based management practices to simultaneously address production and pollution problems has been infeasible. Here we report the outcome of concerted efforts in engaging millions of Chinese smallholder farmers to adopt enhanced management practices for greater yield and environmental performance. First, we conducted field trials across China's major agroecological zones to develop locally applicable recommendations using a comprehensive decision-support program. Engaging farmers to adopt those recommendations involved the collaboration of a core network of 1,152 researchers with numerous extension agents and agribusiness personnel. From 2005 to 2015, about 20.9 million farmers in 452 counties adopted enhanced management practices in fields with a total of 37.7 million cumulative hectares over the years. Average yields (maize, rice and wheat) increased by 10.8-11.5%, generating a net grain output of 33 million tonnes (Mt). At the same time, application of nitrogen decreased by 14.7-18.1%, saving 1.2 Mt of nitrogen fertilizers. The increased grain output and decreased nitrogen fertilizer use were equivalent to US$12.2 billion. Estimated reactive nitrogen losses averaged 4.5-4.7 kg nitrogen per Megagram (Mg) with the intervention compared to 6.0-6.4 kg nitrogen per Mg without. Greenhouse gas emissions were 328 kg, 812 kg and 434 kg CO equivalent per Mg of maize, rice and wheat produced, respectively, compared to 422 kg, 941 kg and 549 kg CO equivalent per Mg without the intervention. On the basis of a large-scale survey (8.6 million farmer participants) and scenario analyses, we further demonstrate the potential impacts of implementing the enhanced management practices on China's food security and sustainability outlook.
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http://dx.doi.org/10.1038/nature25785DOI Listing
March 2018

Physiological mechanisms contributing to increased water-use efficiency in winter wheat under organic fertilization.

PLoS One 2017 29;12(6):e0180205. Epub 2017 Jun 29.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi, China.

Improving the efficiency of resource utilization has received increasing research attention in recent years. In this study, we explored the potential physiological mechanisms underlying improved grain yield and water-use efficiency of winter wheat (Triticum aestivum L.) following organic fertilizer application. Two wheat cultivars, ChangHan58 (CH58) and XiNong9871 (XN9871), were grown under the same nitrogen (N) fertilizer rate (urea-N, CK; and manure plus urea-N, M) and under two watering regimes (WW, well-watered; and WS, water stress) imposed after anthesis. The M fertilizer treatment had a higher Pn and lower gs and Tr than CK under both water conditions, in particular, it significantly increased WRC and Ψw, and decreased EWLR and MDA under WS. Also, the M treatment increased post-anthesis N uptake by 81.4 and 16.4% under WS and WW, thus increasing post-anthesis photosynthetic capacity and delaying leaf senescence. Consequently, the M treatment increased post-anthesis DM accumulation under WS and WW by 51.5 and 29.6%, WUEB by 44.5 and 50.9%, grain number per plant by 11.5 and 12.2% and 1000-grain weight by 7.3 and 3.6%, respectively, compared with CK. The grain yield under M treatment increased by 23 and 15%, and water use efficiency (WUEg) by 25 and 23%, respectively. The increased WUE under organic fertilizer treatment was due to elevated photosynthesis and decreased Tr and gs. Our results suggest that the organic fertilizer treatment enabled plants to use water more efficiently under drought stress.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180205PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491151PMC
October 2017

IbOr Regulates Photosynthesis under Heat Stress by Stabilizing IbPsbP in Sweetpotato.

Front Plant Sci 2017 8;8:989. Epub 2017 Jun 8.

Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and BiotechnologyDaejeon, South Korea.

The Orange (Or) protein regulates carotenoid biosynthesis and environmental stress in plants. Previously, we reported that overexpression of the sweetpotato [ (L.) Lam] gene () in transgenic (referred to as -OX/At) increased the efficiency of photosystem II (PSII) and chlorophyll content after heat shock. However, little is known about the role of IbOr in PSII-mediated protection against abiotic stress. In this study, comparative proteomics revealed that expression of PsbP (an extrinsic subunit of PSII) is up-regulated in heat-treated -OX/At plants. We then identified and functionally characterized the - gene () from sweetpotato. IbPsbP is predominantly localized in chloroplast, and its transcripts are tissue-specifically expressed and up-regulated in response to abiotic stress. In addition, IbOr interacts with IbPsbP and protects it from heat-induced denaturation, consistent with the observation that transgenic sweetpotato overexpressing maintained higher PSII efficiency and chlorophyll content upon exposure to heat stress. These results indicate that IbOr can protect plants from environmental stress not only by controlling carotenoid biosynthesis but also by directly stabilizing PSII.
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http://dx.doi.org/10.3389/fpls.2017.00989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462972PMC
June 2017

Suppression of the β-carotene hydroxylase gene increases β-carotene content and tolerance to abiotic stress in transgenic sweetpotato plants.

Plant Physiol Biochem 2017 Aug 29;117:24-33. Epub 2017 May 29.

Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Daejeon 34141, South Korea; Department of Green Chemistry and Environmental Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Daejeon 34113, South Korea. Electronic address:

β-carotene, a carotenoid that plays a key photo-protective role in plants is converted into zeaxanthin by β-carotene hydroxylase (CHY-β). Previous work showed that down-regulation of IbCHY-β by RNA interference (RNAi) results in higher levels of β-carotene and total carotenoids, as well as salt stress tolerance, in cultured transgenic sweetpotato cells. In this study, we introduced the RNAi-IbCHY-β construct into a white-fleshed sweetpotato cultivar (cv. Yulmi) by Agrobacterium-mediated transformation. Among the 13 resultant transgenic sweetpotato plants (referred to as RC plants), three lines were selected for further characterization on the basis of IbCHY-β transcript levels. The RC plants had orange flesh, total carotenoid and β-carotene contents in storage roots were 2-fold and 16-fold higher, respectively, than those of non-transgenic (NT) plants. Unlike storage roots, total carotenoid and β-carotene levels in the leaves of RC plants were slightly increased compared to NT plants. The leaves of RC plants also exhibited tolerance to methyl viologen (MV)-mediated oxidative stress, which was associated with higher 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical-scavenging activity. In addition, RC plants maintained higher levels of chlorophyll and higher photosystem II efficiency than NT plants after 250 mM NaCl stress. Yield of storage roots did not differ significantly between RC and NT plants. These observations suggest that RC plants might be useful as a nutritious and environmental stress-tolerant crop on marginal lands around the world.
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http://dx.doi.org/10.1016/j.plaphy.2017.05.017DOI Listing
August 2017

High level of reduced glutathione contributes to detoxification of lipid peroxide-derived reactive carbonyl species in transgenic Arabidopsis overexpressing glutathione reductase under aluminum stress.

Physiol Plant 2017 Oct 23;161(2):211-223. Epub 2017 Jun 23.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, 712100, China.

Lipid peroxide-derived reactive carbonyl species (RCS), generated downstream of reactive oxygen species (ROS), are critical damage-inducing species in plant aluminum (Al) toxicity. In mammals, RCS are scavenged primarily by glutathione (reduced form of glutathione, GSH), but in plant Al stress, contribution of GSH to RCS detoxification has not been evaluated. In this study, Arabidopsis plants overexpressing the gene AtGR1 (accession code At3g24170), encoding glutathione reductase (GR), were generated, and their performance under Al stress was examined. These transgenic plants (GR-OE plants) showed higher GSH levels and GSH/GSSG (oxidized form of GSH) ratio, and an improved Al tolerance as they suffered less inhibition of root growth than wild-type under Al stress. Exogenous application of 4-hydroxy-2-nonenal, an RCS responsible for Al toxicity in roots, markedly inhibited root growth in wild-type plants. GR-OE plants suffered significantly smaller inhibition, indicating that the enhanced GSH level increased the capacity of RCS detoxification. The generation of H O due to Al stress in GR-OE plants was lower by 26% than in wild-type. Levels of various RCS, such as malondialdehyde, butyraldehyde, phenylacetaldehyde, (E)-2-heptenal and n-octanal, were suppressed by more than 50%. These results indicate that high levels of GSH and GSH/GSSG ratio by GR overexpression contributed to the suppression of not only ROS, but also RCS. Thus, the maintenance of GSH level by overexpressing GR reinforces dual detoxification functions in plants and is an efficient approach to enhance Al tolerance.
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http://dx.doi.org/10.1111/ppl.12583DOI Listing
October 2017

Down-regulation of GIGANTEA-like genes increases plant growth and salt stress tolerance in poplar.

Plant Biotechnol J 2017 03 23;15(3):331-343. Epub 2016 Sep 23.

Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Korea.

The flowering time regulator GIGANTEA (GI) connects networks involved in developmental stage transitions and environmental stress responses in Arabidopsis. However, little is known about the role of GI in growth, development and responses to environmental challenges in the perennial plant poplar. Here, we identified and functionally characterized three GI-like genes (PagGIa, PagGIb and PagGIc) from poplar (Populus alba × Populus glandulosa). PagGIs are predominantly nuclear localized and their transcripts are rhythmically expressed, with a peak around zeitgeber time 12 under long-day conditions. Overexpressing PagGIs in wild-type (WT) Arabidopsis induced early flowering and salt sensitivity, while overexpressing PagGIs in the gi-2 mutant completely or partially rescued its delayed flowering and enhanced salt tolerance phenotypes. Furthermore, the PagGIs-PagSOS2 complexes inhibited PagSOS2-regulated phosphorylation of PagSOS1 in the absence of stress, whereas these inhibitions were eliminated due to the degradation of PagGIs under salt stress. Down-regulation of PagGIs by RNA interference led to vigorous growth, higher biomass and enhanced salt stress tolerance in transgenic poplar plants. Taken together, these results indicate that several functions of Arabidopsis GI are conserved in its poplar orthologues, and they lay the foundation for developing new approaches to producing salt-tolerant trees for sustainable development on marginal lands worldwide.
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http://dx.doi.org/10.1111/pbi.12628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5316923PMC
March 2017

Expression analysis and promoter methylation under osmotic and salinity stress of TaGAPC1 in wheat (Triticum aestivum L).

Protoplasma 2017 Mar 3;254(2):987-996. Epub 2016 Aug 3.

Institute of Soil and Water Conservation, Chinese Academy of Sciences, 712100, Yangling, Shaanxi, People's Republic of China.

Cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) catalyzes a key reaction in glycolysis and encoded by a multi-gene family which showed instability expression under abiotic stress. DNA methylation is an epigenetic modification that plays an important role in gene regulation in response to abiotic stress. The comprehension of DNA methylation at promoter region of TaGAPC1 can provide insights into the transcription regulation mechanisms of plant genes under abiotic stress. In this study, we cloned TaGAPC1 genes and its promoters from two wheat genomes, then investigated the expression patterns of TaGAPC1 under osmotic and salinity stress, and analyzed the promoter sequences. Moreover, the methylation patterns of promoters under stress were confirmed. Expression analysis indicated that TaGAPC1 was induced inordinately by stresses in two wheat genotypes with contrasting drought tolerance. Several stress-related cis-acting elements (MBS, DRE, GT1 and LTR et al.) were located in its promoters. Furthermore, the osmotic and salinity stress induced the demethylation of CG and CHG nucleotide in the promoter region of Changwu134. The methylation level of CHG and CHH in promoter of Zhengyin1 was always increased under stresses, and the CG contexts remained unchanged. The cytosine loci of stress-related cis-acting elements also showed different methylation changes in this process. These results provide insights into the relationship between promoter methylation and gene expression, promoting the function investigation of GAPC.
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http://dx.doi.org/10.1007/s00709-016-1008-5DOI Listing
March 2017

Silicon-moderated K-deficiency-induced leaf chlorosis by decreasing putrescine accumulation in sorghum.

Ann Bot 2016 08 20;118(2):305-15. Epub 2016 Jun 20.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation College of Life Sciences,

Background And Aims: Although silicon (Si) has been widely reported to alleviate plant nutrient deficiency, the alleviating effect of Si on potassium (K) deficiency and its underlying mechanism are poorly understood. Here, we examined whether Si-regulated putrescine (Put) metabolisms are involved in Si-alleviated K deficiency.

Methods: Sorghum seedlings were grown in K deficiency solution with and without Si for 15 d. The influence of K deficiency and Si on leaf chlorosis symptoms, K(+) concentration, polyamine (PA) levels, amine oxidase activities, the transcription of Put synthesis genes, antioxidant enzyme activities and H2O2 accumulation were measured.

Key Results: Under K-sufficient conditions, plant growth was not affected by Si application. Si application significantly alleviated the growth inhibition induced by K-deficient stress, however. K deficiency induced leaf chlorosis and reduction in several leaf chlorosis-related metrics, including photosynthesis, efficiency of photosystem II photochemistry, chlorophyll content and chlorophyll a/b ratio; all of these changes were moderated by Si application. Si application did not influence the K(+) concentration in leaves under K-sufficient or K-deficient conditions. It did, however, decrease the excessive accumulation of Put that was otherwise induced by K deficiency. Simultaneously, Put synthesis gene transcription and activation of amine oxidases were down-regulated by Si application under K-deficient conditions. In addition, Si reduced K-deficiency-enhanced antioxidant enzyme activities and decreased K-deficiency-induced H2O2 accumulation.

Conclusions: These results indicate that Si application could reduce K-deficiency-induced Put accumulation by inhibiting Put synthesis and could decrease H2O2 production via PA oxidation. Decreased H2O2 accumulation contributes to the alleviation of cell death, thereby also alleviating K-deficiency-induced leaf chlorosis and necrosis.
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http://dx.doi.org/10.1093/aob/mcw111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4970372PMC
August 2016

Regulation of Galactolipid Biosynthesis by Overexpression of the Rice MGD Gene Contributes to Enhanced Aluminum Tolerance in Tobacco.

Front Plant Sci 2016 30;7:337. Epub 2016 Mar 30.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F UniversityYangling, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water ResourcesYangling, China.

Membrane lipid alterations affect Al tolerance in plants, but little is known about the regulation of membrane lipid metabolism in response to Al stress. Transgenic tobacco (Nicotiana tabacum) overexpressing rice monogalactosyldiacylglycerol (MGDG) synthase (OsMGD) gene and wild-type tobacco plants were exposed to AlCl3, and the impact of Al toxicity on root growth, Al accumulation, plasma membrane integrity, lipid peroxidation and membrane lipid composition were investigated. Compared with the wild type, the transgenic plants exhibited rapid regrowth of roots after removal of Al and less damage to membrane integrity and lipid peroxidation under Al stress, meanwhile, the Al accumulation showed no difference between wild-type and transgenic plants. Lipid analysis showed that Al treatment dramatically decreased the content of MGDG and the ratio of MGDG to digalactosyldiacylglycerol (DGDG) in wild-type plants, while it was unchanged in transgenic plants. The stable of MGDG level and the ratio of MGDG/DGDG contribute to maintain the membrane stability and permeability. Moreover, Al caused a significant increase in phospholipids in wild-type plants, resulting in a high proportion of phospholipids and low proportion of galactolipids, but these proportions were unaffected in transgenic plants. The high proportion of phospholipids could contribute to a higher rate of Al(3+) binding in the membrane and thereby leads to more membrane perturbation and damage. These results show that the regulation of galactolipid biosynthesis could play an important role in maintaining membrane structure and function under Al stress.
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http://dx.doi.org/10.3389/fpls.2016.00337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4811928PMC
April 2016

Genome-wide identification and characterization of Glyceraldehyde-3-phosphate dehydrogenase genes family in wheat (Triticum aestivum).

BMC Genomics 2016 Mar 16;17:240. Epub 2016 Mar 16.

Institute of Soil and Water Conservation, Chinese Academy of Sciences, 712100, Yangling, Shaanxi, PR China.

Background: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a central enzyme in glycolysi, we performed genome-wide identification of GAPDH genes in wheat and analyzed their structural characteristics and expression patterns under abiotic stress in wheat.

Results: A total of 22 GAPDH genes were identified in wheat cv. Chinese spring; the phylogenetic and structure analysis showed that these GAPDH genes could be divided into four distinct subfamilies. The expression profiles of GAPDH genes showed tissue specificity all over plant development stages. The qRT-PCR results revealed that wheat GAPDHs were involved in several abiotic stress response.

Conclusions: Wheat carried 22 GAPDH genes, representing four types of plant GAPDHs (gapA/B, gapC, gapCp and gapN). Whole genome duplication and segmental duplication might account for the expansion of wheat GAPDHs. Expression analysis implied that GAPDHs play roles in plants abiotic stress tolerance.
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http://dx.doi.org/10.1186/s12864-016-2527-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4793594PMC
March 2016

Silicon moderated the K deficiency by improving the plant-water status in sorghum.

Sci Rep 2016 Mar 10;6:22882. Epub 2016 Mar 10.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi, 712100, China.

Although silicon (Si) has been widely reported to alleviate plant nutrient deficiency, the underlying mechanism in potassium (K) deficiency is poorly understood. In this study, sorghum seedlings were treated with Si under a K deficiency condition for 15 days. Under control conditions, plant growth was not affected by Si application. The growth and water status were reduced by K-deficient stress, but Si application significantly alleviated these decreases. The leaf gas exchanges, whole-plant hydraulic conductance (Kplant), and root hydraulic conductance (Lpr) were reduced by K deficiency, but Si application moderated the K-deficiency-induced reductions, suggesting that Si alleviated the plant hydraulic conductance. In addition, 29% of Si-alleviated transpiration was eliminated by HgCl2 treatment, suggesting that aquaporin was not the primary cause for the reversal of plant hydraulic conductance. Moreover, the K(+) concentration in xylem sap was significantly increased and the xylem sap osmotic potential was decreased by Si application, suggesting that the major cause of Si-induced improvement in hydraulic conductance could be ascribed to the enhanced xylem sap K(+) concentration, which increases the osmotic gradient and xylem hydraulic conductance. The results of this study show that Si mediates K(+) accumulation in xylem, which ultimately alleviates the plant-water status under the K-deficient condition.
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http://dx.doi.org/10.1038/srep22882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4785406PMC
March 2016

Transgenic poplar expressing codA exhibits enhanced growth and abiotic stress tolerance.

Plant Physiol Biochem 2016 Mar 12;100:75-84. Epub 2016 Jan 12.

Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 305-806, South Korea; Department of Green Chemistry and Environmental Biotechnology, Korea University of Science and Technology, Daejeon, 305-350, South Korea. Electronic address:

Glycine betaine (GB), a compatible solute, effectively stabilizes the structure and function of macromolecules and enhances abiotic stress tolerance in plants. We generated transgenic poplar plants (Populus alba × Populus glandulosa) expressing a bacterial choline oxidase (codA) gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SC plants). Among the 13 SC plants generated, three lines (SC4, SC14 and SC21) were established based on codA transcript levels, tolerance to methyl viologen-mediated oxidative stress and Southern blot analysis. Growth was better in SC plants than in non-transgenic (NT) plants, which was related to elevated transcript levels of auxin-response genes. SC plants accumulated higher levels of GB under oxidative stress compared to the NT plants. In addition, SC plants exhibited increased tolerance to drought and salt stress, which was associated with increased efficiency of photosystem II activity. Finally, SC plants maintained lower levels of ion leakage and reactive oxygen species under cold stress compared to the NT plants. These observations suggest that SC plants might be useful for reforestation on global marginal lands, including desertification and reclaimed areas.
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http://dx.doi.org/10.1016/j.plaphy.2016.01.004DOI Listing
March 2016

Genotypic Variation in Growth and Physiological Response to Drought Stress and Re-Watering Reveals the Critical Role of Recovery in Drought Adaptation in Maize Seedlings.

Front Plant Sci 2015 12;6:1241. Epub 2016 Jan 12.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F UniversityYangling, China; College of Life Sciences, Northwest A&F UniversityYangling, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water ResourcesYangling, China.

Non-irrigated crops in temperate climates and irrigated crops in arid climates are subjected to continuous cycles of water stress and re-watering. Thus, fast and efficient recovery from water stress may be among the key determinants of plant drought adaptation. The present study was designed to comparatively analyze the roles of drought resistance and drought recovery in drought adaptation and to investigate the physiological basis of genotypic variation in drought adaptation in maize (Zea mays) seedlings. As the seedlings behavior in growth associate with yield under drought, it could partly reflect the potential of drought adaptability. Growth and physiological responses to progressive drought stress and recovery were observed in seedlings of 10 maize lines. The results showed that drought adaptability is closely related to drought recovery (r = 0.714(**)), but not to drought resistance (r = 0.332). Drought induced decreases in leaf water content, water potential, osmotic potential, gas exchange parameters, chlorophyll content, Fv/Fm and nitrogen content, and increased H2O2 accumulation and lipid peroxidation. After recovery, most of these physiological parameters rapidly returned to normal levels. The physiological responses varied between lines. Further correlation analysis indicated that the physiological bases of drought resistance and drought recovery are definitely different, and that maintaining higher chlorophyll content (r = 0.874(***)) and Fv/Fm (r = 0.626(*)) under drought stress contributes to drought recovery. Our results suggest that both drought resistance and recovery are key determinants of plant drought adaptation, and that drought recovery may play a more important role than previously thought. In addition, leaf water potential, chlorophyll content and Fv/Fm could be used as efficient reference indicators in the selection of drought-adaptive genotypes.
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http://dx.doi.org/10.3389/fpls.2015.01241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4709455PMC
January 2016

Regulation Effects of Water and Nitrogen on the Source-Sink Relationship in Potato during the Tuber Bulking Stage.

PLoS One 2016 11;11(1):e0146877. Epub 2016 Jan 11.

Stata Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences / Northwest A&F University, Yangling, Shaanxi, China.

The source-sink relationship determines crop yield, and it is largely regulated by water and nutrients in agricultural production. This has been widely investigated in cereals, but fewer studies have been conducted in root and tuber crops such as potato (Solanum tuberosum L.). The objective of this study was to investigate the source-sink relationship in potato and the regulation of water and nitrogen on the source-sink relationship during the tuber bulking stage. A pot experiment using virus-free plantlets of the Atlantic potato cultivar was conducted, using three water levels (50%, 70% and 90% of field capacity) and three nitrogen levels (0, 0.2, 0.4 g N∙kg-1 soil). The results showed that, under all water and nitrogen levels, plant source capacity were small at the end of the experiment, since photosynthetic activity in leaves were low and non-structural reserves in underground stems were completely remobilized. While at this time, there were very big differences in maximum and minimum tuber number and tuber weight, indicating that the sink tuber still had a large potential capacity to take in assimilates. These results suggest that the source-supplied assimilates were not sufficient enough to meet the demands of sink growth. Thus, we concluded that, unlike cereals, potato yield is more likely to be source-limited than sink-limited during the tuber bulking stage. Water and nitrogen are two key factors in potato production management. Our results showed that water level, nitrogen level and the interaction between water and nitrogen influence potato yield mainly through affecting source capacity via the net photosynthetic rate, total leaf area and leaf life span. Well-watered, sufficient nitrogen and well-watered combined with sufficient nitrogen increased yield mainly by enhancing the source capacity. Therefore, this suggests that increasing source capacity is more crucial to improve potato yield.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0146877PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4709089PMC
July 2016

Silicon enhanced salt tolerance by improving the root water uptake and decreasing the ion toxicity in cucumber.

Front Plant Sci 2015 17;6:759. Epub 2015 Sep 17.

State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University Yangling, China ; Institute of Soil and Water Conservation, Chinese Academy of Sciences Yangling, China.

Although the effects of silicon application on enhancing plant salt tolerance have been widely investigated, the underlying mechanism has remained unclear. In this study, seedlings of cucumber, a medium silicon accumulator plant, grown in 0.83 mM silicon solution for 2 weeks were exposed to 65 mM NaCl solution for another 1 week. The dry weight and shoot/root ratio were reduced by salt stress, but silicon application significantly alleviated these decreases. The chlorophyll concentration, net photosynthetic rate, transpiration rate and leaf water content were higher in plants treated with silicon than in untreated plants under salt stress conditions. Further investigation showed that salt stress decreased root hydraulic conductance (Lp), but that silicon application moderated this salt-induced decrease in Lp. The higher Lp in silicon-treated plants may account for the superior plant water balance. Moreover, silicon application significantly decreased Na(+) concentration in the leaves while increasing K(+) concentration. Simultaneously, both free and conjugated types of polyamines were maintained at high levels in silicon-treated plants, suggesting that polyamines may be involved in the ion toxicity. Our results indicate that silicon enhances the salt tolerance of cucumber through improving plant water balance by increasing the Lp and reducing Na(+) content by increasing polyamine accumulation.
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http://dx.doi.org/10.3389/fpls.2015.00759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4585001PMC
October 2015

Carbon/Nitrogen Imbalance Associated with Drought-Induced Leaf Senescence in Sorghum bicolor.

PLoS One 2015 28;10(8):e0137026. Epub 2015 Aug 28.

College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi, 712100, China.

Drought stress triggers mature leaf senescence, which supports plant survival and remobilization of nutrients; yet leaf senescence also critically decreases post-drought crop yield. Drought generally results in carbon/nitrogen imbalance, which is reflected in the increased carbon:nitrogen (C:N) ratio in mature leaves, and which has been shown to be involved in inducing leaf senescence under normal growth conditions. Yet the involvement of the carbon/nitrogen balance in regulation of drought-induced leaf senescence is unclear. To investigate the role of carbon/nitrogen balance in drought-induced senescence, sorghum seedlings were subjected to a gradual soil drought treatment. Leaf senescence symptoms and the C:N ratio, which was indicated by the ratio of non-structural carbohydrate to total N content, were monitored during drought progression. In this study, leaf senescence developed about 12 days after the start of drought treatment, as indicated by various senescence symptoms including decreasing photosynthesis, photosystem II photochemistry efficiency (Fv/Fm) and chlorophyll content, and by the differential expression of senescence marker genes. The C:N ratio was significantly enhanced 10 to 12 days into drought treatment. Leaf senescence occurred in the older (lower) leaves, which had higher C:N ratios, but not in the younger (upper) leaves, which had lower C:N ratios. In addition, a detached leaf assay was conducted to investigate the effect of carbon/nitrogen availability on drought-induced senescence. Exogenous application of excess sugar combined with limited nitrogen promoted drought-induced leaf senescence. Thus our results suggest that the carbon/nitrogen balance may be involved in the regulation of drought-induced leaf senescence.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0137026PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4552878PMC
May 2016

Transgenic poplar expressing Arabidopsis YUCCA6 exhibits auxin-overproduction phenotypes and increased tolerance to abiotic stress.

Plant Physiol Biochem 2015 Sep 9;94:19-27. Epub 2015 May 9.

Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, South Korea; Department of Green Chemistry and Environmental Biotechnology, Korea University of Science and Technology, Daejeon 305-350, South Korea. Electronic address:

YUCCA6, a member of the YUCCA family of flavin monooxygenase-like proteins, is involved in the tryptophan-dependent IAA biosynthesis pathway and responses to environmental cues in Arabidopsis. However, little is known about the role of the YUCCA pathway in auxin biosynthesis in poplar. Here, we generated transgenic poplar (Populus alba × P. glandulosa) expressing the Arabidopsis YUCCA6 gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SY plants). Three SY lines (SY7, SY12 and SY20) were selected based on the levels of AtYUCCA6 transcript. SY plants displayed auxin-overproduction morphological phenotypes, such as rapid shoot growth and retarded main root development with increased root hair formation. In addition, SY plants had higher levels of free IAA and early auxin-response gene transcripts. SY plants exhibited tolerance to drought stress, which was associated with reduced levels of reactive oxygen species. Furthermore, SY plants showed delayed hormone- and dark-induced senescence in detached leaves due to higher photosystem II efficiency and less membrane permeability. These results suggest that the conserved IAA biosynthesis pathway mediated by YUCCA family members exists in poplar.
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http://dx.doi.org/10.1016/j.plaphy.2015.05.003DOI Listing
September 2015
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