水稻叶片衰老基因LPS1的克隆与功能研究

【目的】早衰突变体是研究早衰机制的良好载体,对于探究早衰的遗传机理与作用机制及提高水稻的产量和品质具有重要作用。【方法】本研究利用EMS诱变获得了一个早衰突变体lps1,并对该突变体及其野生型进行表型观察、细胞学及组织化学分析、生理生化分析、遗传分析、基因定位和激素处理。【结果】lps1的叶片从3叶期开始发黄,成熟期株高、有效分蘖数、结实率、千粒重等极显著降低。电镜观察发现lps1叶表面光滑,硅质化突起和叶绿体数目减少、片层结构紊乱。生理生化分析表明lps1中有大量的活性氧积累,同时伴有蛋白质的降解、细胞膜的损伤以及大规模的细胞死亡。遗传分析表明该早衰表型受单隐性核基因控制,并且其在第5染色体上编码了一个泛素结合酶。亚细胞定位结果证明LPS1蛋白在细胞质与核中均有表达。外源激素处理发现,lps1对外源激素的处理更为敏感,且LPS1突变促进了ABA合成相关基因的表达。【结论】LPS1 突变使水稻ABA合成信号途径异常,进而引发H₂O₂等一系列与衰老相关生理指标的异常变动,导致lps1过早衰老,最终造成水稻产量严重降低。

Cloning and Functional Analysis of Leaf Senescence Gene LPS1 in Oryza sativa

【Objective】 As a good carrier, the premature aging mutant plays an important role in exploring the genetic mechanism and mechanism of action on premature aging, as well as improving grain yield and quality of rice.【Method】 In this study, a premature senescence mutant lps1 was obtained by EMS mutagenesis, and phenotypic observation, cytological and histochemical analysis, physiological and biochemical analysis, genetic analysis, gene localization and hormone treatment were performed on wild-type and mutants.【Result】 The leaves of lps1 began to turn yellow during the three-leaf stage, and the plant height, effective tiller number, seed-setting rate, and thousand-grain weight were extremely significantly reduced in the maturing stage. Electron microscopy observation found that the surface of lps1 leaves was smooth, the numbers of silicified protrusions and chloroplasts decreased, and the lamella structure was disordered. Physiological and biochemical analysis showed that a large amount of reactive oxygen species accumulated in mutant lps1, accompanied by protein degradation, cell membrane damage and large-scale cell death. Genetic analysis showed that the progeria phenotype was controlled by a single recessive nuclear gene, which encodes an ubiquitin conjugating enzyme on chromosome 5. The subcellular localization results prove that LPS1 protein is expressed in both the cytoplasm and the nucleus. Exogenous hormone treatment demonstrated that the lps1 was more sensitive to exogenous hormone treatment, and the LPS1 mutation promoted the expression of genes related to ABA synthesis.【Conclusion】 LPS1 mutation makes the rice ABA synthesis signal pathway abnormal, which in turn triggers abnormal changes in a series of aging-related physiological indicators such as H₂O₂, leading to premature senescence of lps1, and ultimately resulting in a serious decrease in rice yield.