名优谷子品种晋谷21优异米质基因发掘及其功能研究

Foxtail millet (Setaria italica (L.) Beauv.) is one of the important minor crops in Northern China. There have been a number of excellent cultivars since 1949, breakthroughs have been made in hybrid foxtail millet during the recent years, and hybrid seeds are being promoted in a large area. However, breeding for quality millet lags behind, with no breakthrough in the production of high quality millet, mainly due to the limited resources of parental lines with high quality millet. One of the main reasons for this is due to the lack of understanding of the molecular mechanism of millet quality, which restrained the establishment of core collections of high quality millet, their application in breeding and molecular breeding. Jingu21 (or Jinfen7 originally) has been recognized as one of the few best quality millet for over 20 years since it was bred by mutagenesis from Jinfen52, been awarded the millet Champion five times in the National Agriculture Product Exhibition. We propose here to compare the whole genome sequence of Jingu21 and its parental line Jinfen52 in order to find the locus related to the high quality millet in Jingu21, and investigate the transcriptomic features related to the high quality millet in Jingu21 by comparison between the transcriptomes of Jingu21 and Jinfen52 during key stages of millet formation; the genetic and transcriptomic characteristics of Jingu21 would be traced in the cultivars and bybrids bred from Jingu21 to study their inheritance and variation, expression and their relationship with millet quality; investigate the function of the genes related to high quality of millet through transgenic plants and mutants.Through these, the molecular mechanism on the formation of millet quality may be established, which could promote the full usage of gene resources related to millet quality and breeding for high quality millet in foxtail millet.

谷子是我国北方重要杂粮,建国以来育出许多优良品种,近年来杂交种培育有重大突破且正大面积推广,然而品质育种却比较滞后，优质亲本来源单调、新品种米质没有大的突破。主要原因之一是对米质形成机制了解甚少，严重影响优异米质核心资源的创建与利用、制约品质分子育种进程。晋谷21（原晋汾7号）从晋汾52诱变育成后20年来一直被公认为顶级米质品种，五次获全国农业博览会优质谷米金奖。我们拟比较晋谷21与其诱变亲本全基因组序列，以期发现形成其优异米质的相关基因位点，并通过转录组测序分析探讨优异米质相关的转录组特征；进而追踪与探索晋谷21遗传背景、优异米质特异基因位点及转录组特征在以晋谷21为亲本育成的12个优质米品种及杂交种当中的遗传变异、表达及其与品质的关系；利用转基因植物和突变体分析优异米质相关基因功能，探索晋谷21 品质形成的分子机制，为充分利用优异品质基因资源、加速谷子品质育种奠定基础。

建国以来育出许多优良品种,然而在品质育种方面,表现出亲本来源单调，优异米质品种没有大的突破。晋谷21号育成20多年来一直被公认为顶级米质，五次获全国农博会优质谷米金奖，目前在生产上仍占主导地位。如此优异的品质，已有一系列以其为亲本育成的衍生优质品种/杂交种，为从基因组学探讨优异品质形成的分子基础提供了极为难得的机会和充实的材料基础。. 本项目通过分析晋谷21与其诱变亲本晋汾52和衍生品种全基因组序列，筛选出了类胡萝卜素合成和降解途径相关基因的SNP位点有3315个（含启动子区域），其中检测出的JG21特异位点有35个，这35个特异位点主要分布在类胡萝卜素代谢途径中四个基因家族上，为发掘利用晋谷21优异品质分子标记奠定了基础。综合晋谷21与其诱变亲本晋汾52和衍生品种全基因组序列及灌浆过程中籽粒转录组分析，初步确定了米色形成关键基因CCD并构建了转化载体，正在进行植物转化及功能验证，不但为快速培育优质米品种提供分子标记，也将为利用基因编辑技术改良谷子品质奠定基础。利用谷子转录组数据开展了基于权重基因共表达网络的类胡萝卜素代谢途径调控因子的分析，发现了一批在类胡萝卜素代谢调控网络模块中起枢纽作用的转录因子，不但为深入探索谷子类胡萝卜素代谢调控指出了方向，也可能为植物类胡萝卜素代谢调控提出重要的理论。我们还针对晋谷21小米蒸煮过程中的挥发性物质进行了分析，并发现晋谷21小米在蒸煮过程中释放的部分香味物质可能与其米色深，即类胡萝卜素含量高有关系。. 总之，本项目从基因组、转录组水平对晋谷21与其诱变亲本晋汾52和衍生品种进行了分析，发现了晋谷21优异品质性状相关的关键基因和可能的调控因子，为深入发掘优质性状相关基因并开展谷子品质育种奠定了基础。