Two hydroxypyruvate reductases encoded by OsHPR1 and OsHPR2 are involved in photorespiratory metabolism in rice  

作　　者：Nenghui Ye Guozhen Yang Yan Chen Chan Zhang Jianhua Zhang Xinxiang Peng 

机构地区：[1]State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University [2]Shenzhen Research Institute, The Chinese University of Hong Kong [3]State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong

出　　处：《Journal of Integrative Plant Biology》2014年第2期170-180,共11页植物学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (U1201212; 31170222);the Shenzhen Overseas Talents Innovation and Entrepreneurship Funding Scheme (The Peacock Scheme);China Postdoctoral Science Foundation (2013M530374)

摘　　要：Mutations in the photorespiration pathway dis- play a lethal phenotype in atmospheric air, which can be fully recovered by elevated C02. An exception is that mutants of peroxisomal hydroxypyruvate reductase （HPR1） do not have this phenotype, indicating the presence of cytosolic bypass in the photorespiration pathway. In this study, we constructed overexpression of the OsHPR1 gene and RNA interference plants of OsHPR1 and OsHPR2 genes in rice （Oryza sativo L. cv. Zhonghua 11）. Results from reverse transcription-polymerase chain reaction （RT-PCR）, Western blot, and enzyme assays showed that HPR1 activity changed significantly in corresponding transgenic lines without any effect on HPR2 activity, which is the same for HPR2. However, metabolite analysis and the serine glyoxylate aminotransferase （SGAT） activity assay showed that the metabolite flux of photorespiration was disturbed in RNAi lines of both HPR genes. Furthermore, HPR1 and HPR2 proteins were located to the peroxisome and cytosol, respectively, by transient expression experiment. Double mutant hprl x hpr2 was generated by crossing individual mutant of hprl and hpr2. The phenotypes of all transgenic lines were determined in ambient air and C02-elevated air. The phenotype typical of photorespiration mutants was observed only where activity of both HPRI and HPR2 were downregulated in the same line. These findings demonstrate that two hydroxypyruvate reductases encoded by OsHPRI and OsHPR2 are involved in photorespiratory metabolism in rice.Mutations in the photorespiration pathway dis- play a lethal phenotype in atmospheric air, which can be fully recovered by elevated C02. An exception is that mutants of peroxisomal hydroxypyruvate reductase （HPR1） do not have this phenotype, indicating the presence of cytosolic bypass in the photorespiration pathway. In this study, we constructed overexpression of the OsHPR1 gene and RNA interference plants of OsHPR1 and OsHPR2 genes in rice （Oryza sativo L. cv. Zhonghua 11）. Results from reverse transcription-polymerase chain reaction （RT-PCR）, Western blot, and enzyme assays showed that HPR1 activity changed significantly in corresponding transgenic lines without any effect on HPR2 activity, which is the same for HPR2. However, metabolite analysis and the serine glyoxylate aminotransferase （SGAT） activity assay showed that the metabolite flux of photorespiration was disturbed in RNAi lines of both HPR genes. Furthermore, HPR1 and HPR2 proteins were located to the peroxisome and cytosol, respectively, by transient expression experiment. Double mutant hprl x hpr2 was generated by crossing individual mutant of hprl and hpr2. The phenotypes of all transgenic lines were determined in ambient air and C02-elevated air. The phenotype typical of photorespiration mutants was observed only where activity of both HPRI and HPR2 were downregulated in the same line. These findings demonstrate that two hydroxypyruvate reductases encoded by OsHPRI and OsHPR2 are involved in photorespiratory metabolism in rice.

关 键 词：PHOTORESPIRATION hydroxypyruvate reductase RNAINTERFERENCE alternative splicing rice （Oryza sativa L.） 

分 类 号：S511[农业科学—作物学]