稻飞虱性别决定分子机理研究

Sex determination is one of the fundamental problems in biology. Revealing the sex determination molecular mechanisms for important insect pests is not only very valuable for basic biology, but also very important for insect pest control both in theory and practice. Sex determination cascade in several known holometabolous insects but silkworm is: sexual instruction signal→ female switch gene Transformer(tra)/ Fem→doublesex (dsx) →executive genes. In the cascade, tra and dsx are two conserved genes. However, up to date, no gene homologous to tra/fem are found in any hemimetabolous insect genomes, and no sexual instruction signal is revealed in hemimetabolous insects. In our pilot studies, we confirmed a dsx in the brown planthopper, and more importantly, we luckily found a gene we tentatively named Pfm which could regulate the sex-specific alternative transcription of dsx, maternal RNAi of Pfm resulted all offspring becoming male or pseudomale. Based on these finding, we will further conduct studies on cascade relationship among Pfm and other sex determination genes, so as to reveal if the planthoppers also possess a tra→dsx -like sex determination cascade as that in holometabolous insects, and to understand the specificity and conservation in the sex determination of hemimetabolous insects. We will also compare the differences and similarities in the sex determination mechanisms in three rice planthoppers, the brown planthopper, white backed planthopper and small brown planthopper, which differ in chromosome numbers. Finally, we will edit the genome of the brown planthopper using CRISPR/Cas9+Gene-drive technology to explore a way for using sex determination genes in rice planthopper control.

性别决定是生物学基本问题，研究重要害虫性别决定机理，不仅具重要理论意义，对害虫防治也具重要实际价值。已知全变态昆虫性别决定基本级联为：初始因子→性别开关基因Tra→双性基因dsx→执行基因，其中tra和dsx是保守的。但至今不完全变态昆虫基因组中还未发现tra的同源基因，初始因子更是不清。我们在前期研究中，确定了褐飞虱dsx，特别是幸运地筛到了能调控dsx转录本性别特异性剪切的1个上游因子（暂名为Pfm），对该基因进行母体RNAi可使后代全为雄/假雄性。本研究拟在此基础上，深入研究Pfm和其它性别基因的级联关系，以明确稻飞虱性别决定是否存在类似于全变态昆虫的tra→dsx保守级联，以揭示不全变态昆虫性别决定级联特性，并比较染色体数量存在差异的褐飞虱、白背飞虱和灰飞虱性别决定异同点。最后通过CRISPR/Cas9+Gene drive探索将性别决定基因应用于稻飞虱遗传防控的途径。