Lu Wenyun, Deng Minjuan, Guo Fu, Wang Mingqiang, Zeng Zhanghui, Han Ning, Yang Yinong, Zhu Muyuan, Bian Hongwu
Institute of Genetics and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China.
State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
Rice (N Y). 2016 Dec;9(1):65. doi: 10.1186/s12284-016-0138-x. Epub 2016 Nov 29.
Vacuolar processing enzymes (VPEs) are cysteine proteinases that act as crucial mediators of programmed cell death (PCD) in plants. In rice, however, the role of VPEs in abiotic stress-induced PCD remains largely unknown. In this study, we generated OsVPE3 overexpression and suppression transgenic lines to elucidate the function of this gene in rice.
Survival rate and chlorophyll retention analyses showed that suppression of OsVPE3 clearly enhanced salt stress tolerance in transgenic rice compared with wild type. Furthermore, fragmentation of genomic DNA was inhibited in plants with down-regulated OsVPE3. Vital staining studies indicated that vacuole rupture occurred prior to plasma membrane collapse during salt-induced PCD. Notably, overexpression of OsVPE3 promoted vacuole rupture, whereas suppression of OsVPE3 attenuated or delayed the disintegration of vacuolar membranes. Moreover, we found that suppression of OsVPE3 caused decreased leaf width and guard cell length in rice.
Taken together, these results indicated that suppression of OsVPE3 enhances salt tolerance by attenuating vacuole rupture during PCD. Therefore, we concluded that OsVPE3 plays a crucial role in vacuole-mediated PCD and in stomatal development in rice.
液泡加工酶（VPEs）是半胱氨酸蛋白酶，在植物程序性细胞死亡（PCD）中起关键介导作用。然而，在水稻中，VPEs在非生物胁迫诱导的PCD中的作用仍 largely未知。在本研究中，我们构建了OsVPE3过表达和抑制转基因系，以阐明该基因在水稻中的功能。
存活率和叶绿素保留分析表明，与野生型相比，OsVPE3的抑制明显增强了转基因水稻的盐胁迫耐受性。此外，在OsVPE3下调的植物中，基因组DNA片段化受到抑制。活体染色研究表明，在盐诱导的PCD过程中，液泡破裂先于质膜崩溃发生。值得注意的是，OsVPE3的过表达促进了液泡破裂，而OsVPE3的抑制减弱或延迟了液泡膜的解体。此外，我们发现OsVPE3的抑制导致水稻叶片宽度和保卫细胞长度减小。
综上所述，这些结果表明，OsVPE3的抑制通过减弱PCD过程中的液泡破裂来增强耐盐性。因此，我们得出结论，OsVPE3在水稻液泡介导的PCD和气孔发育中起关键作用。
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