水稻蜡质合成基因WSL5调控衰老与抗逆分子机理研究

蜡质是植物抵御外界侵害的第一道防护层，调控蜡质合成是水稻抗逆育种的有效途径之一。但已被克隆的水稻蜡质合成相关基因较少，分子机制更不甚清楚。因此，挖掘新种质资源，阐明蜡质合成调控机制十分必要。本项目前期获得一个蜡质合成缺陷突变体wsl5，其叶片沾水，表面蜡质稀，蜡质组分含量少；wsl5抽穗后叶绿素迅速降解，呈现早衰；突变体光合速率、粒型、花粉活性和结实率均比野生型要低，产量和品质均变差。遗传分析表明wsl5受单隐性核基因控制，图位克隆将其定位于第4染色体52 kb区间，测序发现突变体中LOC_Os04g30760第9外显子发生突变，表达量降低。功能互补确定LOC_Os04g30760就是WSL5基因，是一个新的蜡质合成相关基因。本项目拟通过转基因、表达谱分析、原核表达、蜡质成分测定和胁迫处理等方法对WSL5的功能全面解读，将完善水稻蜡质合成和调控的遗传机制，丰富水稻抗逆育种思路。

The aerial parts of plants are covered with cuticular waxes, which form the first barrier between plants and the environment. Regulating wax biosynthesis is an effective way for rice stress-tolerance breeding. However, few genes involved in wax metabolism have been reported, and their mechanism are little known, restraining their effective use. Thus, it is necessary that mining and utilizating new germplasm resources of wax synthesis and regulation, and investigating the possible mechanism. In this proposal, we have obtained a wax-deficient mutant from ZH11 mutagenesis population, named wsl5. This mutant exhibits stronger water adhesiveness than ZH11,caused by less and thinner wax on the leaf surface, and all wax component content are decreased. Chlorophyll is degrade rapidly after heading in the mutant, leading to obvious premature senility phenotype. Compared with ZH11, wsl5 have lower photosynthetic rate, smaller grains and thousand kernel weight, lower pollen activity and seedset, leading to lower yield and worse grain quality. Genetic analysis indicates that wsl5 is controlled by a single recessive nuclear gene. Via map-based cloning, WSL5 is fine mapped in a 52 kb region on chromosome 4. Sequencing indicates that there is single base substitution in the 9th exon of LOC_Os04g30760 in this region, and this gene is lower expressed in wsl5. The functional complementation analysis verify that LOC_Os04g30760 is the WSL5. No papers about this gene were published, so WSL5 is a new gene involved in wax biosynthesis. Base on these findings, genetical transformations, RNA-seq, prokaryotic expression, enzyme activity assay, wax content assay, electron microscope analysis and stresses-tolerance identification will be employed to perliminarily ascertain the biological functions of WSL5. This study will complement the molecular mechanism for wax synthesis and regulation, enrich approach for rice stresses-tolerance breeding.