一份人工合成新型耐涝玉米材料的耐涝机理研究

Flooding (including waterlooging) is the second natural disaster causing maize production decline. Exploiting the flooding-tolerant gene and creating flooding-tolerant germplasm, and breeding flooding-tolerant variety are the key factors to solve the problem. As a xerophilous plant, cultivated maize shows a loss of flood-tolerance due to declined genetic diversity in the process of domesticating and directional selecting. However, teosinte, a wild relative of maize chronically growing in the moist environment, reserves flooding-tolerance feature. In a former research, we systematically assessed the flooding-tolerance of seven species of teosinte. Zea nicaraguensis, the strongest flooding-tolerant species was chosen as the donor parent to improve the flooding-tolerance of maize inbredline 08-641. Later a genetic stable flooding-tolerant "maize" was obtained in progeny of the BC4F2 generation. In this research, we plan to identify the traits closely related to flooding-tolerance characteristics by combination of morphological, anatomical, and physiological methods; reveal the gene expressional regulatory networks using transcriptome sequencing; clone the flooding-tolerant genes and their promoters using homologues cloning, RACE, or TAIL-PCR; validate the function of cloned genes and promoters by combination of transgenic Arabidopsis and single segment introgression line; and develop exon-based molecular maker of flooding-tolerant genes. This research not only technically lays the foundation for flooding-tolerant hybrid breeding in later work, but also promote the exploiting of flooding-tolerant gerplasm of other teosinte.

水涝是造成玉米减产的第二大自然灾害，发掘耐涝基因，创制耐涝材料，培育耐涝品种是解决问题的关键。可栽培玉米为旱生作物，经人工驯化栽培和长期定向选择，遗传多样性大幅下降，基本丧失耐涝性。玉米的野生近源种大刍草保留了栽培玉米不具有的耐涝性。本研究在对7个大刍草种耐涝性系统评价基础上，选用耐涝性最强的尼加拉瓜大刍草为供体亲本，改良西南区骨干玉米自交系08-641的耐涝性，在BC4F2中筛选出一份遗传稳定的耐涝材料。本研究将采用形态学、解剖学、生理学的研究方法鉴定与耐涝性密切相关的性状；采用转录组测序揭示新材料的耐涝分子调控网络；采用同源克隆、RACE或TAIL-PCR克隆耐涝基因及其启动子；结合拟南芥转基因和单片段导入系对基因及其启动子进行功能验证；并开发基于外显子的特异耐涝基因分子标记。该研究不仅可以为玉米杂交种耐涝性的提高打下基础，而且还可促进对其它大刍草耐涝基因资源的发掘与利用。

水涝是造成玉米减产的第二大自然灾害，发掘耐涝基因，创制耐涝材料，培育耐涝品种是解决问题的关键。可栽培玉米为旱生作物，经人工驯化栽培和长期定向选择，遗传多样性大幅下降，基本丧失耐涝性。玉米的野生近源种大刍草保留了栽培玉米不具有的耐涝性。本研究在对7个大刍草种耐涝性系统评价基础上，选用耐涝性最强的尼加拉瓜大刍草为供体亲本，改良西南区骨干玉米自交系08-641的耐涝性，在BC4F2中筛选出一份遗传稳定的耐涝材料。本研究采用形态学、解剖学、生理学的研究方法鉴定出耐涝性密切相关的2个性状：通气组织和根系活力；建立了以尼加拉瓜大刍草为外源基因供体培育新型耐涝玉米自交系的技术体系，目前正在开展该自交系的配合力测定和杂交组配工作；对尼加拉瓜转录组测序数据进行分析，总计发掘9837条全长转录本，为后期进行基因克隆和功能验证奠定基础，以这些全长转录本与玉米、高粱的单拷贝基因进行分析，构建系统发育树，确定栽培玉米与大刍草的遗传分化时间为1.6 百万年；通过对新型耐涝材料及其轮回亲本自交系的转录组测序，比较各时间点基因表达调控网络的差异，揭示了新型耐涝材料耐涝性优于轮回亲本的分子机理；基于SNP分型确定新型耐涝材料中来源于尼加拉瓜大刍草的基因总计358个，结合已有的QTL定位数据，筛选到控制通气组织形成的主效基因的2个候选基因，并开发了相应的SNP标记；培养研究生4名，已在SCI期刊上公开发表SCI收录论文1篇；已完成F2群体构建，今年上半年将对F2群体进行抗涝相关性状鉴定，结合BSA分析，确定导入基因所在区域，再结合转录组测序数据，进一步筛选与通气组织形成、ROL、根系活力相关的候选基因，并开展候选基因克隆和验证的工作。