Publications by authors named "Chaoxing He"

17 Publications

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Correction to: The CsGPA1-CsAQPs module is essential for salt tolerance of cucumber seedlings.

Plant Cell Rep 2021 Oct;40(10):2015-2016

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Haidian District, Zhongguancun South St, Beijing, 100081, China.

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http://dx.doi.org/10.1007/s00299-021-02782-6DOI Listing
October 2021

Adaptation of cucumber seedlings to low temperature stress by reducing nitrate to ammonium during it's transportation.

BMC Plant Biol 2021 Apr 19;21(1):189. Epub 2021 Apr 19.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.

Background: Low temperature severely depresses the uptake, translocation from the root to the shoot, and metabolism of nitrate and ammonium in thermophilic plants such as cucumber (Cucumis sativus). Plant growth is inhibited accordingly. However, the availability of information on the effects of low temperature on nitrogen transport remains limited.

Results: Using non-invasive micro-test technology, the net nitrate (NO) and ammonium (NH) fluxes in the root hair zone and vascular bundles of the primary root, stem, petiole, midrib, lateral vein, and shoot tip of cucumber seedlings under normal temperature (NT; 26 °C) and low temperature (LT; 8 °C) treatment were analyzed. Under LT treatment, the net NO flux rate in the root hair zone and vascular bundles of cucumber seedlings decreased, whereas the net NH flux rate in vascular bundles of the midrib, lateral vein, and shoot tip increased. Accordingly, the relative expression of CsNRT1.4a in the petiole and midrib was down-regulated, whereas the expression of CsAMT1.2a-1.2c in the midrib was up-regulated. The results of N isotope tracing showed that NO-N and NH-N uptake of the seedlings under LT treatment decreased significantly compared with that under NT treatment, and the concentration and proportion of both NO-N and NH-N distributed in the shoot decreased. Under LT treatment, the actual nitrate reductase activity (NRA) in the root did not change significantly, whereas NRA in the stem and petiole increased by 113.2 and 96.2%, respectively.

Conclusions: The higher net NH flux rate in leaves and young tissues may reflect the higher NRA in the stem and petiole, which may result in a higher proportion of NO being reduced to NH during the upward transportation of NO. The results contribute to an improved understanding of the mechanism of changes in nitrate transportation in plants in response to low-temperature stress.
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http://dx.doi.org/10.1186/s12870-021-02918-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8056598PMC
April 2021

Application of hollow fiber centrifugal ultrafiltrate purification as the pretreatment technology for traditional Chinese medicine: its application for analysis of honokiol and magnolol in TCM preparations containing Cortex Magnoliae Officinalis.

Ann Palliat Med 2021 Jun 17;10(6):6359-6366. Epub 2021 Mar 17.

Department of Pharmacy, Hebei General Hospital, Shijiazhuang, China.

Background: Traditional Chinese medicine (TCM) preparations are very complex mixtures, and the content of bioactive components is usually very low. Therefore, before final analysis, the preparation of an appropriate sample is necessary. Sample preparation is the most time-consuming and error-prone part of the analytical procedure, and the choice of purification technology greatly influences the reliability of the final analysis.

Methods: In the present study, we evaluated the feasibility of hollow fiber centrifugal ultrafiltrate (HFCF-UF) as a purification technology for the analysis of bioactive components in TCM preparations. The HFCF-UF technology was applied to analyze honokiol and magnolol in TCM preparations containing Cortex Magnoliae Officinalis (Hou Po in Chinese Pinyin). A mini centrifugal device based on hollow fiber was employed to remove the macromolecule components. A single step of simple centrifugation was required before the filtrate could be directly injected into an existing high performance liquid chromatography (HPLC) system without any further clean-up step or use of special columns. This greatly simplified the pretreatment steps, and improved the accuracy of analytic methods. The separation was achieved on a Diamonsil C18 column (i.d. 5 µm, 150 mm × 4.6 mm) with V (methanol):V (acetonitrile):V (0.5% acetic acid solution) =44:22:34 as the mobile phase at a flow rate of 1.0 mL/min.

Results: It had good linear relationship between the peak areas of honokiol and magnolol and their concentrations at 6.40-205 and 3.15-101 µg/mL (r=0.9999), respectively. The method recovery was over 92.6% with a relative standard deviation (RSD) of less than 3.0%. The average recovery of honokiol was 97.7% with an RSD of 3.0%, and that of magnolol was 96.8% with RSD of 2.8%.

Conclusions: The application of HFCF-UF in TCM preparations could assist in making the quality control of TCM simple, rapid, and accurate. The HFCF-UF purification procedure can be used as an alternative means for analyzing bioactive components in TCM preparations.
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http://dx.doi.org/10.21037/apm-21-242DOI Listing
June 2021

The CsGPA1-CsAQPs module is essential for salt tolerance of cucumber seedlings.

Plant Cell Rep 2020 Oct 9;39(10):1301-1316. Epub 2020 Jul 9.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Haidian District, Zhongguancun South St, Beijing, 100081, China.

Key Message: CsGPA1 interacts with CsTIP1.1 (a member of CsAQPs) and suppression of CsGPA1 results the reverse expression of CsAQPs in leaves and roots, resulting in declining water content of cucumber seedlings under salt stress. Salt stress seriously affects cucumber growth and development. Whether the G-protein alpha subunit functions in cucumber during salt stress and its regulation mechanism remains unknown. We interrogated CsGPA1-RNAi lines to identify the role of CsGPA1 during salt stress. Phenotypically, compared with wild type, leaves were severely withered, and root cells showed signs of senescence under salt stress for RNAi lines. Compared with WT, SOD and CAT activity, soluble protein and proline contents all decreased in RNAi lines, while malondialdehyde and relative electrical conductivity increased. Through screening the yeast two-hybrid library and combined with yeast two-hybrid and GST pull-down, the interaction of CsGPA1 with CsTIP1.1 was found the first time in a plant. Then, the expression of aquaporin (AQP) family genes was detected. The expression of CsAQP genes in leaves and roots was primarily up-regulated in WT under salt stress. However, interference by CsGPA1 resulted in enhanced expression of CsAQPs except for CsTIP3.2 in leaves, but reduced expression of some CsAQPs in roots under salt stress. Furthermore, principal component analysis of CsAQP expression profiles and linear regression analysis between CsGPA1 and CsAQPs revealed that CsGPA1 reversely regulated the expression of CsAQPs in leaves and roots under salt stress. Moreover, the water content in leaves and roots of RNAi seedlings significantly decreased compared with WT under salt stress. Overall, CsGPA1 interacts with CsTIP1.1 and suppression of CsGPA1 results in opposite patterns of expression of CsAQPs in leaves and roots, resulting in declining water content of cucumber under salt stress.
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http://dx.doi.org/10.1007/s00299-020-02565-5DOI Listing
October 2020

Vasodilation activity of dipfluzine metabolites in isolated rat basilar arteries and their underlying mechanisms.

Environ Toxicol Pharmacol 2020 Oct 13;79:103430. Epub 2020 Jun 13.

College of Pharmacy, Hebei Medical University, Shijiazhuang, China. Electronic address:

Identifying the metabolites of a drug has become an indispensable task in the development of new drugs. Dipfluzine (Dip) is a promising candidate for the treatment of cerebral vascular diseases and has 5 metabolites (M1∼M5) in rat urine and liver microsomes, but their biological activity is still unknown. Because selective cerebral vasodilation is a main role of Dip, we investigated the vasodilation of Dip and its 5 metabolites in isolated Sprague-Dawley (SD) male rat basilar arteries preconstricted with high-K or 5-HT. The results showed that only M1 possessed concentration-dependent inhibitory activity on the vasoconstriction of arteries with or without the endothelium, and M1 has a more potent vasodilatory effect than Dip on both contraction models. Like Dip, the vasodilatory mechanisms of M1 may be not only related to receptor-operated and voltage-dependent calcium ion channels of smooth muscle cells but also to the release of NO and EDHF from endothelial cells and the opening of Ca-activated K channels and ATP-sensitive potassium ion channels. Unlike Dip, the vasodilation mechanism of M1 is also related to the opening of voltage-sensitive K channel. Together with more selectivity to non-VDCC than Dip, this may partially explain why M1 has stronger vasodilatory effects than Dip. The mechanisms of vasodilation of Dip and M1 may result from the combined action of these or other factors, especially blocking non-endothelium dependent non-VDCC and endothelium dependent IK channels. These results point to the possibility that M1 provides synergism for the clinical use of Dip, which may inform the synthesis of new drugs.
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http://dx.doi.org/10.1016/j.etap.2020.103430DOI Listing
October 2020

Correction to: 24-Epibrassinolide promotes NO and NH ion flux rate and NRT1 gene expression in cucumber under suboptimal root zone temperature.

BMC Plant Biol 2019 Oct 28;19(1):453. Epub 2019 Oct 28.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.

In the original publication of this article [1], the author pointed out there is an error in Figs. 4 and 5.
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http://dx.doi.org/10.1186/s12870-019-2089-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6816212PMC
October 2019

Genome-Wide Identification and Characterization of Cucumber BPC Transcription Factors and Their Responses to Abiotic Stresses and Exogenous Phytohormones.

Int J Mol Sci 2019 Oct 11;20(20). Epub 2019 Oct 11.

Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

BASIC PENTACYSTEINE (BPC) is a small transcription factor family that functions in diverse growth and development processes in plants. However, the roles of BPCs in plants, especially cucumber ( L.), in response to abiotic stress and exogenous phytohormones are still unclear. Here, we identified four BPC genes in the cucumber genome, and classified them into two groups according to phylogenetic analysis. We also investigated the gene structures and detected five conserved motifs in these . Tissue expression pattern analysis revealed that the four were expressed ubiquitously in both vegetative and reproductive organs. Additionally, the transcriptional levels of the four were induced by various abiotic stress and hormone treatments. Overexpression of in tobacco () inhibited seed germination under saline, polyethylene glycol, and abscisic acid (ABA) conditions. The results suggest that the CsBPC genes may play crucial roles in cucumber growth and development, as well as responses to abiotic stresses and plant hormones. overexpression in tobacco negatively affected seed germination under hyperosmotic conditions. Additionally, functioned in ABA-inhibited seed germination and hypersensitivity to ABA-mediated responses. Our results provide fundamental information for further research on the biological functions of BPCs in development and abiotic stress responses in cucumber and other plant species.
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http://dx.doi.org/10.3390/ijms20205048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6829308PMC
October 2019

Integrated Metabolome and Transcriptome Analysis Provide Insights into the Effects of Grafting on Fruit Flavor of Cucumber with Different Rootstocks.

Int J Mol Sci 2019 Jul 23;20(14). Epub 2019 Jul 23.

Institute of Vegetables and Flowers, Chinese Academy of Agriculture Sciences, Beijing 100081, China.

Rootstocks frequently exert detrimental effects on the fruit quality of grafted cucumber ( L.) plants. To understand and ultimately correct this deficiency, a transcriptomic and metabolomic comparative analysis was performed among cucumber fruits from non-grafted plants (NG), and fruits from plants grafted onto different rootstocks of No.96 and No.45 ( Duch), known to confer a different aroma and taste. We found remarkable changes in the primary metabolites of sugars, organic acids, amino acids, and alcohols in the fruit of the grafted cucumber plants with different rootstocks, compared to the non-grafted ones, especially No.45. We identified 140, 131, and 244 differentially expressed genes (DEGs) in the comparisons of GNo.96 vs. NG, GNo.45 vs. NG, and GNo.45 vs. GNo.96. The identified DEGs have functions involved in many metabolic processes, such as starch and sucrose metabolism; the biosynthesis of diterpenoid, carotenoid, and zeatin compounds; and plant hormone signal transduction. Members of the HSF, AP2/ERF-ERF, HB-HD-ZIP, and MYB transcription factor families were triggered in the grafted cucumbers, especially in the cucumber grafted on No.96. Based on a correlation analysis of the relationships between the metabolites and genes, we screened 10 candidate genes likely to be involved in sugar metabolism (Fructose-6-phosphate and trehalose), linoleic acid, and amino-acid (isoleucine, proline, and valine) biosynthesis in grafted cucumbers, and then confirmed the gene expression patterns of these genes by qRT-PCR. The levels of (Csa3G040850) were remarkably increased in cucumber fruit with No.96 rootstock compared with No.45, suggesting changes in the volatile chemical production. Together, the results of this study improve our understanding of flavor changes in grafted cucumbers, and identify the candidate genes involved in this process.
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http://dx.doi.org/10.3390/ijms20143592DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6678626PMC
July 2019

24-Epibrassinolide promotes NO and NH ion flux rate and NRT1 gene expression in cucumber under suboptimal root zone temperature.

BMC Plant Biol 2019 May 30;19(1):225. Epub 2019 May 30.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.

Background: Suboptimal root zone temperature (RZT) causes a remarkable reduction in growth of horticultural crops during winter cultivation under greenhouse production. However, limited information is available on the effects of suboptimal RZT on nitrogen (N) metabolism in cucumber seedlings. The aim of this study is to investigate the effects of 24-Epibrassinolide (EBR) on nitrate and ammonium flux rate, N metabolism, and transcript levels of NRT1 family genes under suboptimal RZT in cucumber seedlings.

Results: Suboptimal RZT (LT) negatively affected on cucumber growth and proportionately decreased EBR contents, bleeding rate, root activity, enzyme activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT), nitrate (NO) influx rate, ammonium (NH) efflux rate, and transcript levels of nitrate transporter (NRT1) encoding genes. However, exogenous EBR reduced the harmful effects of suboptimal RZT and increased endogenous EBR contents, bleeding rate, root activity, enzyme activities of NR, NiR, GS, and GOGAT, NH and NO flux rates and contents, and N accumulation. EBR-treated seedlings also upregulated the transcript levels of nitrate transporters CsNRT1.1, CsNRT1.2A, CsNRT1.2B, CsNRT1.2C, CsNRT1.3, CsNRT1.4A, CsNRT1.5B, CsNRT1.5C, CsNRT1.9, and CsNRT1.10, and downregulated CsNRT1.5A and CsNRT1.8. LT treatment upregulated the expression level of CsNRT1.5A, while exogenous BZR application downregulated the expression level of NRT1 genes.

Conclusion: These results indicate that exogenous application of EBR alleviated the harmful effects of suboptimal RZT through changes in N metabolism, NH and NO flux rates, and NRT1 gene expression, leading to improved cucumber seedlings growth. Our study provides the first evidence of the role of EBR in the response to suboptimal RZT in cucumber, and can be used to improve vegetable production.
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http://dx.doi.org/10.1186/s12870-019-1838-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543628PMC
May 2019

Selection of reference genes for quantitative real-time PCR analysis in cucumber ( L.), pumpkin ( Duch) and cucumber-pumpkin grafted plants.

PeerJ 2019 17;7:e6536. Epub 2019 Apr 17.

Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.

Background: Quantitative real-time PCR (qRT-PCR) is a commonly used high-throughput technique to measure mRNA transcript levels. The accuracy of this evaluation of gene expression depends on the use of optimal reference genes. Cucumber-pumpkin grafted plants, made by grafting a cucumber scion onto pumpkin rootstock, are superior to either parent plant, as grafting conveys many advantages. However, although many reliable reference genes have been identified in both cucumber and pumpkin, none have been obtained for cucumber-pumpkin grafted plants.

Methods: In this work, 12 candidate reference genes, including eight traditional genes and four novel genes identified from our transcriptome data, were selected to assess their expression stability. Their expression levels in 25 samples, including three cucumber and three pumpkin samples from different organs, and 19 cucumber-pumpkin grafted samples from different organs, conditions, and varieties, were analyzed by qRT-PCR, and the stability of their expression was assessed by the comparative ΔCt method, geNorm, NormFinder, BestKeeper, and RefFinder.

Results: The results showed that the most suitable reference gene varied dependent on the organs, conditions, and varieties. and were the most stable reference genes for all samples in our research. and showed the most stable expression in different cucumber organs, and were the optimal reference genes in pumpkin organs, and and were the most stable genes in all grafted cucumber samples. However, the optimal reference gene varied under different conditions. and were the best combination of genes in different organs of cucumber-pumpkin grafted plants, and were the most stable in the graft union under cold stress, and showed the most stable expression in the graft union during the healing process, and and were the most stable across different varieties of cucumber-pumpkin grafted plants. The use of , and + as reference genes were further verified by analyzing the expression levels of , , and in the graft union at different time points after grafting.

Discussion: This work is the first report of appropriate reference genes in grafted cucumber plants and provides useful information for the study of gene expression and molecular mechanisms in cucumber-pumpkin grafted plants.
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http://dx.doi.org/10.7717/peerj.6536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6475253PMC
April 2019

Functions of CsGPA1 on the hypocotyl elongation and root growth of cucumbers.

Sci Rep 2018 10 22;8(1):15583. Epub 2018 Oct 22.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South St, Haidian District, Beijing, 100081, China.

G proteins regulate shoot, root, and epidermis development, as well as biotic stress tolerance in plants; however, most studies have examined model plants and less attention has been paid to the function of G proteins in horticultural plants. Here, we identified a G protein, CsGPA1, from cucumber and studied its function in seedling development of cucumbers. CsGPA1 is a peptide of 392 amino acids with a predicted molecular mass of 44.6 kDa. Spatiotemporal expression analysis found that endogenous CsGPA1 was highly expressed in roots and young leaves. Immunohistochemical assay revealed that functional CsGPA1 was present in the plasma membranes of the epidermis and cortex, and in the cytosol of the endodermis, parenchyma, and vasculature of root meristematic cells. In comparison with wild-type seedlings, CsGPA1-overexpressing transgenic lines exhibited enhanced seed germination and earlier seedling development including hypocotyl elongation and root growth. In contrast, RNAi silencing of the CsGPA1 gene inhibited seedling growth and development. Further study showed that CsGPA1 controled hypocotyl elongation and root growth via promoting cell size and the meristem of hypocotyl and root tip cells of cucumber plants. Our study expands the roles of G proteins in plants and helps to elucidate the mechanism by which cucumber regulates early seedling development.
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http://dx.doi.org/10.1038/s41598-018-33782-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6197229PMC
October 2018

Heterotrimeric G-Protein γ Subunit CsGG3.2 Positively Regulates the Expression of Genes and Chilling Tolerance in Cucumber.

Front Plant Sci 2018 17;9:488. Epub 2018 Apr 17.

Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.

Heterotrimeric guanine nucleotide-binding proteins (G proteins) composed of alpha (Gα), beta (Gβ), and gamma (Gγ) subunits are central signal transducers mediating the cellular response to multiple stimuli, such as cold, in eukaryotes. Plant Gγ subunits, divided into A, B, and C three structurally distinct types, provide proper cellular localization and functional specificity to the heterotrimer complex. Here, we demonstrate that a type C Gγ subunit CsGG3.2 is involved in the regulation of the regulon and plant tolerance to cold stresses in cucumber ( L.). We showed that transcript abundance was positively induced by cold treatments. Transgenic cucumber plants (T1) constitutively over-expressing exhibits tolerance to chilling conditions and increased expression of genes and their regulon. Antioxidative enzymes, i.e., superoxide dismutase, catalase, peroxidase, and glutathione reductase activities increased in cold-stressed transgenic plants. The reactive oxygen species, oxygen free radical and HO, production, as well as membrane lipid peroxidation (MDA) production decreased in transgenic plants, suggesting a better antioxidant system to cope the oxidative-damages caused by cold stress. These findings provide evidence for a critical role of CsGG3.2 in mediating cold signal transduction in plant cells.
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http://dx.doi.org/10.3389/fpls.2018.00488DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913349PMC
April 2018

Cucumber CsBPCs Regulate the Expression of during Seed Germination.

Front Plant Sci 2017 3;8:459. Epub 2017 Apr 3.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural SciencesBeijing, China.

Cucumber seeds with shallow dormancy start to germinate in fruit that are harvested late. ABSCISIC ACID INSENSITIVE3 (ABI3), a transcription factor in the abscisic acid (ABA) signaling pathway, is one of the most important regulators in the transition from late embryogenesis to germination. Our analysis found a candidate cis-regulatory motif for cucumber BASIC PENTACYSTEINE (CsBPC) in the promoter of . Yeast one-hybrid and chromatin immunoprecipitation (ChIP) assays showed that CsBPCs bound to the promoter of . Examination of β-glucuronidase (GUS) activity driven by the promoter in transgenic plants overexpressing and a (tobacco) luciferase assay indicated that CsBPCs inhibited the expression of . Transgenic plants overexpressing were constructed to confirm that CsBPCs participates in the control of seed germination. This study of the cucumber BPC-ABI3 pathway will help to explore and characterize the molecular mechanisms underlying seed germination and will provide necessary information for seed conservation in agriculture and forestry.
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http://dx.doi.org/10.3389/fpls.2017.00459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5376566PMC
April 2017

Impact of arbuscular mycorrhizal fungi (AMF) on cucumber growth and phosphorus uptake under cold stress.

Funct Plant Biol 2015 Dec;42(12):1158-1167

Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.

Symbiosis with root-associated arbuscular mycorrhizal fungi (AMF) can improve plant phosphorus (P) uptake and alleviate environmental stresses. It could be also an effective mean to promote plant performance under low temperatures. The combined effects of arbuscular mycorrhiza and low temperature (15°C/10°C day/night) on cucumber seedlings were investigated in the present study. Root colonisation by AMF, succinate dehydrogenase and alkaline phosphatase activity in the intraradical fungal structures, plant growth parameters, and expression profiles of four cucumber phosphate (Pi) transporters, the fungal Pi transporter GintPT and alkaline phosphatase GintALP were determined. Cold stress reduced plant growth and mycorrhizal colonisation. Inoculation improved cucumber growth under ambient temperatures, whereas under cold stress only root biomass was significantly increased by inoculation. AMF supplied P to the host plant under ambient temperatures and cold stress, as evidenced by the higher P content of mycorrhizal plants compared with non-mycorrhizal plants. Thus, the cold-stressed cucumber seedlings still benefited from mycorrhiza, although the benefit was less than that under ambient temperatures. In accordance with this, a cucumber Pi transporter gene belonging to the Pht1 gene family was strongly induced by mycorrhiza at ambient temperature and to a lesser extent under cold stress. The other three Pi transporters tested from different families were most highly expressed in cold-stressed mycorrhizal plants, suggesting a complex interactive effect of mycorrhiza and cold stress on internal P cycling in cucumber plants.
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http://dx.doi.org/10.1071/FP15106DOI Listing
December 2015

Arbuscular mycorrhizae improve low temperature tolerance in cucumber via alterations in H2O2 accumulation and ATPase activity.

J Plant Res 2014 Nov 27;127(6):775-85. Epub 2014 Aug 27.

College of Forestry, Henan University of Science and Technology, Luoyang, 471003, People's Republic of China.

The combined effects of arbuscular mycorrhizal fungi (AMF) and low temperature (LT) on cucumber plants were investigated with respect to biomass production, H2O2 accumulation, NADPH oxidase, ATPase activity and related gene expression. Mycorrhizal colonization ratio was gradually increased after AMF-inoculation. However, LT significantly decreased mycorrhizal colonization ability and mycorrhizal dependency. Regardless of temperature, the total fresh and dry mass, and root activity of AMF-inoculated plants were significantly higher than that of the non-AMF control. The H2O2 accumulation in AMF-inoculated roots was decreased by 42.44% compared with the control under LT. H2O2 predominantly accumulated on the cell walls of apoplast but was hardly detectable in the cytosol or organelles of roots. Again, NADPH oxidase activity involved in H2O2 production was significantly reduced by AMF inoculation under LT. AMF-inoculation remarkably increased the activities of P-type H(+)-ATPase, P-Ca(2+)-ATPase, V-type H(+)-ATPase, total ATPase activity, ATP concentration and plasma membrane protein content in the roots under LT. Additionally, ATP concentration and expression of plasma membrane ATPase genes were increased by AMF-inoculation. These results indicate that NADPH oxidase and ATPase might play an important role in AMF-mediated tolerance to chilling stress, thereby maintaining a lower H2O2 accumulation in the roots of cucumber.
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http://dx.doi.org/10.1007/s10265-014-0657-8DOI Listing
November 2014

Grafting-responsive miRNAs in cucumber and pumpkin seedlings identified by high-throughput sequencing at whole genome level.

Physiol Plant 2014 Aug 27;151(4):406-22. Epub 2013 Nov 27.

The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.

Grafting is an important agricultural technique widely used for improving growth, yields and tolerance of crops to abiotic and biotic stresses. As one type of endogenous, non-coding small RNAs, microRNAs (miRNAs) regulate development and responsiveness to biotic and abiotic stresses by negatively mediating expression of target genes at the post-transcriptional level. However, there have been few detailed studies to evaluate the role of miRNAs in mediation of grafting-induced physiological processes in plants. Cucumis sativus and Cucurbita moschata are important vegetables worldwide. We constructed eight small RNA libraries from leaves and roots of seedlings that were grafted in the following four ways: (1) hetero-grafting, using cucumber as scion and pumpkin as rootstock; (2) hetero-grafting, with pumpkin as scion and cucumber as rootstock; (3) auto-grafting of cucumbers and (4) auto-grafting of pumpkins. High-throughput sequencing was employed, and more than 120 million raw reads were obtained. We annotated 112 known miRNAs belonging to 40 miRNA families and identified 48 new miRNAs in the eight libraries, and the targets of these known and novel miRNAs were predicted by bioinformatics. Grafting led to changes in expression of most miRNAs and their predicted target genes, suggesting that miRNAs may play significant roles in mediating physiological processes of grafted seedlings by regulating the expression of target genes. The potential role of the grafting-responsive miRNAs in seedling growth and long-distance transport of miRNA was discussed. These results are useful for functional characterization of miRNAs in mediation of grafting-dependent physiological processes.
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http://dx.doi.org/10.1111/ppl.12122DOI Listing
August 2014

Changes of antioxidative enzymes and cell membrane osmosis in tomato colonized by arbuscular Mycorrhizae under NaCl stress.

Colloids Surf B Biointerfaces 2007 Oct 5;59(2):128-33. Epub 2007 May 5.

Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, Beijing 100081, PR China.

Salinity toxicity is a worldwide agricultural and eco-environmental problem. Many literatures show that arbuscular mycorrhizal fungi (AMF) can enhance salt tolerance of many plants and some physiological changes occurred in AM symbiosis under salt stress. However, the role of ROS-scavenging enzymes in AM tomato is still unknown in continuous salt stress. This study investigated the effect of Glomus mosseae on tomato growth, cell membrane osmosis and examined the antioxidants (superoxide-dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; peroxidase, POD) responses in roots of mycorrhizal tomato and control under different NaCl stress for 40 days in potted culture. NaCl solution (0, 0.5 and 1%) was added to organic soil in the irrigation water after 45 days inoculated by AMF (Glomus mosseae). (1) AMF inoculation improved tomato growth under salt or saltless condition and reduced cell membrane osmosis, MDA (malonaldehyde) content in salinity. So the salt tolerance of tomato was enhanced by AMF; (2) SOD, APX and POD activity in roots of AM symbiosis were significantly higher than corresponding non-AM plants in salinity or saltless condition. However, CAT activity was transiently induced by AMF and then suppressed to a level similar with non-AM seedlings; (3) higher salinity (1% level) and long stress time suppressed the effect of AMF on SOD, APX, POD and CAT activity; (4) this research suggested that the enhanced salt tolerance in AM symbiosis was mainly related with the elevated SOD, POD and APX activity by AMF which degraded more reactive oxygen species and so alleviated the cell membrane damages under salt stress. Whereas, the elevated SOD, POD and APX activity due to AMF depended on salinity environment.
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http://dx.doi.org/10.1016/j.colsurfb.2007.04.023DOI Listing
October 2007
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