超级杂交水稻LYP9及其亲本的转录组学研究

A Transcriptome Analysis of Superhybrid Rice LYP9 and its Parents

水稻既是重要的粮食作物和基础研究的模式植物,也是杂种优势利用的成功典范。尽管杂种优势的利用在解决世界粮食安全问题上已做出重大的贡献,但杂种优势的分子机制在生物学和农学的基础研究中依然是一个有待阐明的重要课题。本研究利用水稻全基因组芯片,系统考察了超级杂交稻"两优培九"及其双亲——"培矮64s"(母本)和"93-11"(父本)在7个不同发育时期的组织中的基因表达谱,旨在揭示杂种一代(F1)与亲本的基因表达差异,并从中发现可能与杂种优势相关的基因。实验结果表明,从转录谱来看,杂种F1与亲本间的相似性大于亲本之间的相似性;在发现的3000多个杂种和亲本间差异表达的基因中,有各种不同的差异表达类型,多数是偏于单亲的显性表达,但也有只在杂种中出现的超亲表达。对差异表达基因的功能分类表明,虽然差异表达基因涉及诸多功能类群,但在少数功能类群(如能量代谢、碳水化合物代谢、转运等)中有明显的富集。对差异表达基因的基因组位置与产量相关的QTL(数量性状位点)进行关联分析的结果表明,差异表达基因在水稻基因组中的分布与QTL、尤其是与小区间的QTL有密切的关联;值得注意的是,部分落在QTL上的差异表达基因的功能注释有助于解释与QTL对应的体现杂种优势的农艺性状。

Although utilizing heterosis in crop breeding has made great contributions to the world-wide food supply,the molecular mechanism of heterosis remains a major issue to be solved in biology and agricultural science. Rice is not only a major staple food and a model plant for basic researches,but also an apotheosis in successfully utilizing heterosis. The present study applied the rice whole-genome gene microarray to make a comparative transcriptome analysis of the superhybrid rice,LYP9 and its two parental lines,PA64s （maternal） and 93-11 （paternal）,to disclose gene expression differences between the hybrid and the two parents. The results showed that the similarity in transcriptome between the hybrid and either parent was larger than that between the two parents. Among the more than 3,000 differentially expressed genes （DGs）,the dominant expressions took the majority. Functional classification of DGs revealed that DGs were involved in many functional categories,but enriched only in a few of them （such as energy metabolism,carbohydrate metabolism and transport,etc.）. Results of mapping DGs to QTL （quantitative trait loci） indicated a good association between the two dataset. It is noted that DGs tend to be enriched in QTL of small interval,and some DGs seem to underlie the traits of the relative QTL. The study implies that the mechanism of heterosis in rice may be further deciphered in this way though heterosis is a rather complex biological phenomenon.