title: Enhanced drought tolerance in transgenic rice over-expressing of maize C4 phosphoenolpyruvate carboxylase gene via NO and Ca(2+).
abstract: We determined the effects of endogenous nitric oxide and Ca(2+) on photosynthesis and gene expression in transgenic rice plants (PC) over-expressing the maize C4pepc gene, which encodes phosphoenolpyruvate carboxylase (PEPC) under drought. In this study, seedlings were subjected to PEG 6000 treatments using PC and wild type (WT; Kitaake). The results showed that, compared with WT, PC had higher relative water content (RWC) and net photosynthetic rate (Pn) under drought. During a 2-day re-watering treatment, Pn recovered faster in PC than in WT. Further analyses showed that, under the drought treatment, the amount of endogenous hydrogen peroxide (H2O2) increased in WT mainly via NADPH oxidase. While in PC, the endogenous nitric oxide (NO) content increased via nitrate reductase and nitric oxide synthase on day 2 of the drought treatment and day 1 of the re-watering treatment. After 2 days of drought treatment, PC also showed higher PEPC activity, calcium content, phospholipase D (PLD) activity, C4-pepc and NAC6 transcript levels, and protein kinase activity as compared with PC without treatment. These changes did not occur in WT. Correlation analysis also proved NO associated with these indicators in PC. Based on these results, there was a particular molecular mechanism of drought tolerance in PC. The mechanism is related to the signaling processes via NO and Ca(2+) involving the protein kinase and the transcription factor, resulted in up-regulation of PEPC activity and its gene expression, such as C4pepc. Some genes encode antioxidant system, cu/zn-sod as well, which promote antioxidant system to clear MDA and superoxide anion radical, thereby conferring drought tolerance.
authors.affiliation: Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu High Quality Rice R & D Center, Nanjing Branch, China National Center for Rice Improvement, Provincial Key Laboratory of Agrobiology, Nanjing 210014, PR China; College of Life Science, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Baoyun
authors.initials: B
authors.lastname: Qian
authors.affiliation: Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu High Quality Rice R & D Center, Nanjing Branch, China National Center for Rice Improvement, Provincial Key Laboratory of Agrobiology, Nanjing 210014, PR China. Electronic address: lixiahappy2008@gmail.com.
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu High Quality Rice R & D Center, Nanjing Branch, China National Center for Rice Improvement, Provincial Key Laboratory of Agrobiology, Nanjing 210014, PR China; College of Life Science, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu High Quality Rice R & D Center, Nanjing Branch, China National Center for Rice Improvement, Provincial Key Laboratory of Agrobiology, Nanjing 210014, PR China.
authors.forename: Pingbo
authors.initials: P
authors.lastname: Chen
authors.affiliation: Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu High Quality Rice R & D Center, Nanjing Branch, China National Center for Rice Improvement, Provincial Key Laboratory of Agrobiology, Nanjing 210014, PR China.
authors.forename: Chengang
authors.initials: C
authors.lastname: Ren
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Chuanchao
authors.initials: C
authors.lastname: Dai
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000502:physiology*; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics* / Q000378:metabolism; D010788:Photosynthesis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D013312:Stress, Physiological; D014867:Water / Q000502:physiology; D003313:Zea mays / Q000235:genetics*
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D014867:Water; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010730:Phosphoenolpyruvate Carboxylase; D002118:Calcium
keywords: Ca(2+); Drought; Nitric oxide; PEG6000; Phosphoenolpyruvate carboxylase; Rice (Oryza sativa L.)