小米食味品质性状的全基因组关联分析与优异食味品质资源发掘

Foxtail millet has been paid gread attention by the consumers with the improving living standard over the recent years, yet many millet brands are actually produced from just a few elite varieties, reflecting both the demands by the consumers and the lack of breakthrough in quality breeding.There is not much difference in nutrient value among different varieties, so the consumers are more concerned with the color, eating quality and flavor of the millet. However, there is not much understanding on the mechanism of these traits, greatly restricting the exploration and utilization of the abundant resources of foxtail millet in our country, and hindering the molecular breeding for high quality millet. Based on the demands for millet quality by the consumers and the millet industry, and the urgency to transform the traditional breeding to molecular breeding, we proposed to carry out genome wide association study of the eating quality traits of millets including the millet color before and after cooking, gelatinization property, the characteristics of flavor and related volatile compounds,using 300 germplasm accessions（genome resequencing data available）, in order to discover quality related loci and develop related markers. Then these markers would be used to screen another 600 accessions (genome resequencing data available) for candidates of high quality millet, then their quality would be confirmed so that they could be used as high quality germplasm resources; the genomes of some accessions with high millet quality would be resequenced with high coverage;transcriptomic profiling would be carried out on some accessions with representive eating qualities.Through the work above, we might shed light on the genetic and molecular mechanism behind the eating quality and provide genetic resources and molecular markers for quality breeding.

近年来随着人民生活的改善，优质小米备受推崇。然而许多品牌小米实质上出自个别名优品种，既反映了消费者对小米品质的追求，也表明优异品质新品种选育缺乏大的突破。小米品种间主要营养成分差异小，因而消费者对小米品质的关注主要集中在食味品质。然而对谷子丰富种质资源在食味品质方面的多样性以及食味品质的形成机制却缺乏了解，严重影响我国丰富谷子资源在优异米质资源方面的发掘与利用、制约着品质分子育种。我们拟对300份谷子种质资源进行小米煮前与煮后米色、糊化特性、香味等食味品质关键性状进行多样性分析，对食味性状进行全基因组关联分析以发掘相关基因位点，并在另外600份资源上利用这些位点筛选优质资源且进行品质验证以发现优异食味品质种质，对部分优异资源进行全基因组深度重测序，同时对具代表性的食味资源从转录组水平分析，从而初步探索小米食味品质形成的遗传与分子机制，并为谷子分子品质育种提供亲本材料和分子标记。

随着人民生活的改善，对优质小米需要越来越大。尽管市场上有许多品牌小米，但实质上多出自个别名优品种，既反映了小米品质受到极大的重视，也反映了优异品质新品种选育缺乏突破以及优质品种缺乏多样性。小米品种间主要营养成分差异较小，而且主食完全可以满足主要营养的需求，因而消费者对小米品质的关注点主要集中在食味品质，尤其是米色和蒸煮香味。然而对谷子丰富种质资源在食味品质方面的多样性以及食味品质的形成机制却缺乏了解，严重影响我国丰富谷子资源在优异米质资源方面的发掘与利用、制约着品质分子育种。本项目完成了对300多份中国核心种质谷子资源小米的外观和蒸煮品质性状分析，明确了小米食味品质性状的多样性以及优质小米蒸煮风味特征及关键挥发性物质，小米香味主要以醛类物质为主，种类最多、相对含量较高且阈值低，对小米粥香气的产生具有重要作用；不同蒸煮时间、水质（纯净水、自来水或不同pH）、小米与小米面蒸煮对小米香味的影响不同，蒸煮时间越长挥发性物质释放越多，水质对挥发性物质影响不显著，小米粉比小米释放更多的香味物质。因原计划使用的公共数据库里中国核心资源重测序深度较低，不利于精准发掘基因，我们另筹资金完成400份中国核心资源进行全基因组的深度重测序，即将实施风味和口感相关的全基因组关联分析。初步明确了优异食味品质小米形成过程中转录组特征，并且首次从代谢组水平分析了小米形成过程中代谢产物特点及其与食味品质的关系。首次对小米脂质成分进行了代谢组分析，从晋谷21生米、米汤上清和熟米粒种共鉴定出657种脂质分子，共分属于30种脂质亚类。甘油三酯为小米中主要存在的脂类物质，有245种；其次是甘油二酯（DG）61种，卵磷脂（PC）59种。蒸煮前小米中绝大部分脂质亚类含量显著高于蒸煮之后。蒸煮之后很多磷脂类脂质分子含量增多。本项目为深入探索小米食味品质形成机制以及品质分子育种奠定了基础。