Publications by authors named "Xianchang Yu"

23 Publications

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Agronomic Biofortification of Cayenne Pepper Cultivars with Plant Growth-Promoting Rhizobacteria and Chili Residue in a Chinese Solar Greenhouse.

Microorganisms 2021 Nov 21;9(11). Epub 2021 Nov 21.

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

Agronomic biofortification of horticultural crops using plant growth-promoting rhizobacteria (PGPR) under crop residue incorporation systems remains largely underexploited. (B1), (B2), or (B3) was inoculated on soil containing chili residue, while chili residue without PGPR (NP) served as the control. Two hybrid long cayenne peppers, succeeding a leaf mustard crop were used in the intensive cultivation study. Net photosynthesis, leaf stomatal conductance, transpiration rate, photosynthetic water use efficiency, shoot and root biomass, and fruit yield were evaluated. Derivatives of folate, minerals, and nitrate contents in the pepper fruits were also assessed. B1 elicited higher net photosynthesis and photosynthetic water use efficiency, while B2 and B3 had higher transpiration rates than B1 and NP. B1 and B3 resulted in 27-36% increase in pepper fruit yield compared to other treatments, whereas B3 produced 24-27.5% and 21.9-27.2% higher 5-methyltetrahydrofolate and total folate contents, respectively, compared to B1 and NP. However, chili residue without PGPR inoculation improved fruit calcium, magnesium, and potassium contents than the inoculated treatments. 'Xin Xian La 8 F1' cultivar had higher yield and plant biomass, fruit potassium, total soluble solids, and total folate contents compared to 'La Gao F1.' Agronomic biofortification through the synergy of and chili residue produced better yield and folate contents with a trade-off in the mineral contents of the greenhouse-grown long cayenne pepper.
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http://dx.doi.org/10.3390/microorganisms9112398DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8623771PMC
November 2021

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

Sugars promote graft union development in the heterograft of cucumber onto pumpkin.

Hortic Res 2021 Jul 1;8(1):146. Epub 2021 Jul 1.

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

The use of heterografts is widely applied for the production of several important commercial crops, but the molecular mechanism of graft union formation remains poorly understood. Here, cucumber grafted onto pumpkin was used to study graft union development, and genome-wide tempo-spatial gene expression at the graft interface was comprehensively investigated. Histological analysis suggested that resumption of the rootstock growth occurred after both phloem and xylem reconnection, and the scion showed evident callus production compared with the rootstock 3 days after grafting. Consistently, transcriptome data revealed specific responses between the scion and rootstock in the expression of genes related to cambium development, the cell cycle, and sugar metabolism during both vascular reconnection and healing, indicating distinct mechanisms. Additionally, lower levels of sugars and significantly changed sugar enzyme activities at the graft junction were observed during vascular reconnection. Next, we found that the healing process of grafted etiolated seedlings was significantly delayed, and graft success, xylem reconnection, and the growth of grafted plants were enhanced by exogenous glucose. This demonstrates that graft union formation requires the correct sugar content. Furthermore, we also found that graft union formation was delayed with a lower energy charge by the target of rapamycin (TOR) inhibitor AZD-8055, and xylem reconnection and the growth of grafted plants were enhanced under AZD-8055 with exogenous glucose treatment. Taken together, our results reveal that sugars play a positive role in graft union formation by promoting the growth of cucumber/pumpkin and provide useful information for understanding graft union healing and the application of heterografting in the future.
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http://dx.doi.org/10.1038/s41438-021-00580-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8245404PMC
July 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

Long non-coding RNA KCNQ1OT1 promotes the progression of gastric cancer via the miR-145-5p/ARF6 axis.

J Gene Med 2021 05 6;23(5):e3330. Epub 2021 Apr 6.

Department of Cardiothoracic Surgery, Zhuhai People's Hospital (Zhuhai hospital affiliated with Jinan University), Zhuhai City, Guangdong Province, China.

Background: Long non-coding RNA KCNQ1 opposite strand/antisense transcript one gene (KCNQ1OT1) has been reported to be involved in the progression of many types of human cancer, whereas its role in gastric cancer (GC) remains unknown. The present study aimed to investigate the role of KCNQ1OT1 in GC.

Methods: In total, 25 GC tissues and adjacent normal tissues were collected. The expression of KCNQ1OT1, miR-145-5p and ARF6 in GC tissues and cell lines was detected by quantitative reverse transcriptase-polymerase chain reaction or western blotting. Bioinformatics analysis and a dual luciferase reporter assay were performed to determine the relationship between KCNQ1OT1 and miR-145-5p or miR-145-5p and ARF6. Gain- and loss-of function of KCNQ1OT1 and miR-145-5p were achieved to confirm their roles in GC cells. Cell counting kit-8, colony formation and flow cytometry assays were used to evaluate cell viability, proliferation and apoptosis. A xenograft tumor model was established with BGC803 tumor cells transfected with sh-KCNQ1OT1 or empty vector to determine the role of LINC01089 in vivo.

Results: The expression levels of KCNQ1OT1 were markedly elevated in GC tissues and cells. Knockdown of KCNQ1OT1 inhibited GC tumor growth, reduced GC cell viability and colony formation, and induced GC cell apoptosis. The expression levels of miR-145-5p were significantly decreased in GC cells and correlated with the expression of KCNQ1OT1 in GC tumors. Moreover, KCNQ1OT1 directly binds with miR-145-5p, which is targeting ARF6. Knockdown of KCNQ1OT1 increased the expression levels of miR-145-5p. Inhibition of miR-145-5p increased the expression levels of KCNQ1OT1 and also attenuated the effects of knockdown of KCNQ1OT1 on the viability, proliferation and apoptosis of GC cells. In addition, overexpression of miR-145-5p reduced GC cell viability and colony formation and induced GC cell apoptosis, whereas overexpression of ARF6 attenuated the effects of overexpression of miR-145-5p on GC cell viability, colony formation and apoptosis.

Conclusions: KCNQ1OT1 can promote GC progression through the miR-145-5p/ARF6 axis. KCNQ1OT1 may serve as a therapeutic target and a diagnostic biomarker of GC.
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http://dx.doi.org/10.1002/jgm.3330DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8244094PMC
May 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

Activation of the LINC00242/miR-141/FOXC1 axis underpins the development of gastric cancer.

Cancer Cell Int 2020 24;20:272. Epub 2020 Jun 24.

Department of General Surgery, Zhuhai People's Hospital (Zhuhai hospital affiliated with Jinan University), No.79 Kangning Road, Xiangzhou District, Zhuhai, 519000 Guangdong China.

Background: Long non-coding RNAs (LncRNAs) are a class of newly identified transcripts recognized as critical governors of gene expression during human carcinogenesis, whereas their tumor-suppressive or tumor-promoting effects on gastric cancer (GC) are required for further investigation. In the study, we identify the expression pattern of a novel lncRNA LINC00242 in GC and its possible permissive role in the development of GC.

Methods: The study included 68 pairs of GC and adjacent normal gastric tissue samples. The viability, migration, and invasion of cultured human GC cells HGC27 were evaluated by CCK-8 and Transwell chamber assays. In vitro tube formation of human brain microvascular endothelial cells (HBMVECs) in HGC27 cell coculture was detected. The regulatory network of LINC00242/miR-141/FOXC1 was verified using dual luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay. Subcutaneous xenografts of HGC27 cells were performed in nude mice.

Results: LINC00242 was highly expressed in GC tissues and cells and contributed to poor prognosis. LINC00242 knockdown inhibited HGC27 cell viability, migration and invasion, and tube formation of HBMVECs. LINC00242 interacted with miR-141 and positively regulated FOXC1, a target gene of miR-141. LINC00242 knockdown was partially lost in HGC27 cells upon miR-141 inhibition or FOXC1 overexpression. The tumor-promoting effect of LINC00242 on GC was demonstrated in nude mice.

Conclusion: Taken together, the present study demonstrates the oncogenic role of the LINC00242/miR-141/FOXC1 axis in GC, highlighting a theoretical basis for GC treatment.
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http://dx.doi.org/10.1186/s12935-020-01369-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7313095PMC
June 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

The physiological and molecular mechanism of brassinosteroid in response to stress: a review.

Biol Res 2018 Nov 12;51(1):46. Epub 2018 Nov 12.

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

The negative effects of environmental stresses, such as low temperature, high temperature, salinity, drought, heavy metal stress, and biotic stress significantly decrease crop productivity. Plant hormones are currently being used to induce stress tolerance in a variety of plants. Brassinosteroids (commonly known as BR) are a group of phytohormones that regulate a wide range of biological processes that lead to tolerance of various stresses in plants. BR stimulate BRASSINAZOLE RESISTANCE 1 (BZR1)/BRI1-EMS SUPPRESSOR 1 (BES1), transcription factors that activate thousands of BR-targeted genes. BR regulate antioxidant enzyme activities, chlorophyll contents, photosynthetic capacity, and carbohydrate metabolism to increase plant growth under stress. Mutants with BR defects have shortened root and shoot developments. Exogenous BR application increases the biosynthesis of endogenous hormones such as indole-3-acetic acid, abscisic acid, jasmonic acid, zeatin riboside, brassinosteroids (BR), and isopentenyl adenosine, and gibberellin (GA) and regulates signal transduction pathways to stimulate stress tolerance. This review will describe advancements in knowledge of BR and their roles in response to different stress conditions in plants.
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http://dx.doi.org/10.1186/s40659-018-0195-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231256PMC
November 2018

5-Aminolevulinic Acid Improves Nutrient Uptake and Endogenous Hormone Accumulation, Enhancing Low-Temperature Stress Tolerance in Cucumbers.

Int J Mol Sci 2018 Oct 29;19(11). Epub 2018 Oct 29.

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

5-aminolevulinic acid (ALA) increases plant tolerance to low-temperature stress, but the physiological and biochemical mechanisms that underlie its effects are not fully understood. To investigate them, cucumber seedlings were treated with different ALA concentrations (0, 15, 30 and 45 mg/L ALA) and subjected to low temperatures (12/8 °C day/night temperature). The another group (RT; regular temperature) was exposed to normal temperature (28/18 °C day/night temperature). Low-temperature stress decreased plant height, root length, leaf area, dry mass accumulation and the strong seedling index (SSI), chlorophyll contents, photosynthesis, leaf and root nutrient contents, antioxidant enzymatic activities, and hormone accumulation. Exogenous ALA application significantly alleviated the inhibition of seedling growth and increased plant height, root length, hypocotyl diameter, leaf area, and dry mass accumulation under low-temperature stress. Moreover, ALA increased chlorophyll content (Chl a, Chl b, Chl a+b, and Carotenoids) and photosynthetic capacity, net photosynthetic rate (), stomatal conductance (), intercellular CO₂ concentration (), and transpiration rate (), as well as the activities of superoxide dismutase (SOD), peroxidase (POD, catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) enzymes, while decreasing hydrogen peroxide (H₂O₂), superoxide (O₂), and malondialdehyde (MDA) contents under low-temperature stress. In addition, nutrient contents (N, P, K, Mg, Ca, Cu, Fe, Mn, and Zn) and endogenous hormones (JA, IAA, BR, iPA, and ZR) were enhanced in roots and leaves, and GA4 and ABA were decreased. Our results suggest the up-regulation of antioxidant enzyme activities, nutrient contents, and hormone accumulation with the application of ALA increases tolerance to low-temperature stress, leading to improved cucumber seedling performance.
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http://dx.doi.org/10.3390/ijms19113379DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6275039PMC
October 2018

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

24-Epibrassinolide Ameliorates Endogenous Hormone Levels to Enhance Low-Temperature Stress Tolerance in Cucumber Seedlings.

Int J Mol Sci 2018 Aug 24;19(9). Epub 2018 Aug 24.

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

Phytohormone biosynthesis and accumulation are essential for plant growth and development and stress responses. Here, we investigated the effects of 24-epibrassinolide (EBR) on physiological and biochemical mechanisms in cucumber leaves under low-temperature stress. The cucumber seedlings were exposed to treatments as follows: NT (normal temperature, 26 °C/18 °C day/night), and three low-temperature (12 °C/8 °C day/night) treatments: CK (low-temperature stress); EBR (low-temperature and 0.1 μM EBR); and BZR (low-temperature and 4 μM BZR, a specific EBR biosynthesis inhibitor). The results indicated that low-temperature stress proportionately decreased cucumber seedling growth and the strong seedling index, chlorophyll (Chl) content, photosynthetic capacity, and antioxidant enzyme activities, while increasing reactive oxygen species (ROS) and malondialdehyde (MDA) contents, hormone levels, and EBR biosynthesis gene expression level. However, EBR treatments significantly enhanced cucumber seedling growth and the strong seedling index, chlorophyll content, photosynthetic capacity, activities of antioxidant enzymes, the cell membrane stability, and endogenous hormones, and upregulated EBR biosynthesis gene expression level, while decreasing ROS and the MDA content. Based on these results, it can be concluded that exogenous EBR regulates endogenous hormones by activating at the transcript level EBR biosynthetic genes, which increases antioxidant enzyme capacity levels and reduces the overproduction of ROS and MDA, protecting chlorophyll and photosynthetic machinery, thus improving cucumber seedling growth.
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http://dx.doi.org/10.3390/ijms19092497DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164164PMC
August 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

Gibberellin Is Involved in Inhibition of Cucumber Growth and Nitrogen Uptake at Suboptimal Root-Zone Temperatures.

PLoS One 2016 23;11(5):e0156188. Epub 2016 May 23.

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

Suboptimal temperature stress often causes heavy yield losses of vegetables by suppressing plant growth during winter and early spring. Gibberellin acid (GA) has been reported to be involved in plant growth and acquisition of mineral nutrients. However, no studies have evaluated the role of GA in the regulation of growth and nutrient acquisition by vegetables under conditions of suboptimal temperatures in greenhouse. Here, we investigated the roles of GA in the regulation of growth and nitrate acquisition of cucumber (Cucumis sativus L.) plants under conditions of short-term suboptimal root-zone temperatures (Tr). Exposure of cucumber seedlings to a Tr of 16°C led to a significant reduction in root growth, and this inhibitory effect was reversed by exogenous application of GA. Expression patterns of several genes encoding key enzymes in GA metabolism were altered by suboptimal Tr treatment, and endogenous GA concentrations in cucumber roots were significantly reduced by exposure of cucumber plants to 16°C Tr, suggesting that inhibition of root growth by suboptimal Tr may result from disruption of endogenous GA homeostasis. To further explore the mechanism underlying the GA-dependent cucumber growth under suboptimal Tr, we studied the effect of suboptimal Tr and GA on nitrate uptake, and found that exposure of cucumber seedlings to 16°C Tr led to a significant reduction in nitrate uptake rate, and exogenous application GA can alleviate the down-regulation by up regulating the expression of genes associated with nitrate uptake. Finally, we demonstrated that N accumulation in cucumber seedlings under suboptimal Tr conditions was improved by exogenous application of GA due probably to both enhanced root growth and nitrate absorption activity. These results indicate that a reduction in endogenous GA concentrations in roots due to down-regulation of GA biosynthesis at transcriptional level may be a key event to underpin the suboptimal Tr-induced inhibition of root growth and nitrate uptake. These findings may have important practical implications in effective mitigation of suboptimal temperature-induced vegetable loss under greenhouse conditions.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0156188PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4877016PMC
July 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

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

Ascorbic acid contents in transgenic potato plants overexpressing two dehydroascorbate reductase genes.

Mol Biol Rep 2011 Mar 21;38(3):1557-66. Epub 2010 Sep 21.

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

Ascorbic acid (AsA, vitamin C) is one of the most important nutritional quality factors in many horticultural crops and has many biological activities in the human body. Dehydroascorbate reductase (EC 1.8.5.1; DHAR) plays an important role in maintaining the normal level of ascorbic acid (AsA) by recycling oxidized ascorbic acid. To increase AsA content of potato, we isolated and characterized the cDNAs encoding two isoform DHARs localized in cytosol and chloroplast from potato, and developed two types of transgenic potato plants overexpressing cytosolic DHAR gene and chloroplastic DHAR, respectively. Incorporation of the transgene in the genome of potato was confirmed by PCR and real time RT-PCR. The overexpression of cytosolic DHAR significantly increased DHAR activities and AsA contents in potato leaves and tubers, whereas chloroplastic DHAR overexpression only increased DHAR activities and AsA contents in leaves, and did not change them in tubers. These results indicated that AsA content of potato can be elevated by enhancing recycling ascorbate via DHAR overexpression, moreover, cytosolic DHAR might play main important roles in improving the AsA contents of potato tubers.
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http://dx.doi.org/10.1007/s11033-010-0264-2DOI Listing
March 2011

[Effect of soil water on the growth and physiological characteristics of grafted and non-grafted cucumber in greenhouse].

Ying Yong Sheng Tai Xue Bao 2002 Nov;13(11):1399-402

College of Horticulture, Shangdong Agricultural University, Tai'an 271018.

Studies on the effect of soil water on the growth and physiological characteristics of cucumber in greenhouse showed that water deficit or excessiveness could retard the growth and development of cucumber. The transpire rate, Gs, water potential and root activity decreased quickly due to water deficit.
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November 2002
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