小麦TaSnRK2s在茎秆可溶性糖代谢中的作用解析及优异等位基因发掘

Wheat is one of staple food crops in the world. Environmental stresses such as drought and high temperature significantly restrict wheat production. Mining and utilization of elite germplasm resources to develop new varieties for abiotic stress tolerance is one of most effective and economic ways to meet the challenge. Water soluble carbohydrate (WSC) is a main source for grain filling in wheat. The accumulation and transportation of stem WSC are crucial determinants for grain yield. Improving stem WSC results in enhancements in grain yield and tolerance to abiotic stress at mature stage in wheat. SnRK2, a plant-specific protein kinase subfamily, plays pivotal roles in response to multi-abiotic stresses, root development and WSC metabolism. Thus, SnRK2 has extensive application prospects in crop improvement; however, it has not been fully utilized until now. To bridge the gap, the project aims to clone all the ten members of TaSnRK2 subfamily, identify the members involved in WSC metabolism according to their expression patterns at flowering and grain-filling stages, discover DNA polymorphisms of target genes and develop functional markers for linkage and association analysis, characterize elite alleles for WSC metabolism, reveal the temporal and geographical distributions of elite alleles in historical varieties, mine elite germplasm for improvement of grain yield and abiotic stress tolerance. The project will provide excellent genetic resources and functional markers to stimulate the development of molecular breeding in wheat.

干旱、高温等非生物逆境是制约小麦生产的主要限制因素，培育抗逆高产小麦新品种是应对环境胁迫的重要途径。可溶性糖（WSC）是小麦籽粒灌浆的主要碳源，也是重要的渗透调节物质。提高小麦茎秆WSC含量不仅能增加产量，还能提高成株期抗逆性。SnRK2是植物特有的蛋白激酶亚家族，它不仅能促进根系发育，增强植物的抗逆性，还参与调节WSC代谢，是培育抗逆高产作物新品种的重要基因。本项目拟在前期工作的基础上，克隆小麦TaSnRK2亚家族10个成员的基因组序列，通过基因表达模式分析筛选参与WSC代谢的候选基因；以多态性群体为材料检测目标基因序列多态性，开发功能标记；用功能标记扫描自然群体和遗传连锁群体，进行关联和连锁分析，相互验证结果，发掘与WSC代谢高度相关的优异等位基因，揭示优异等位基因在十大麦区育成品种中的分布特点，发掘优异种质资源，为小麦抗旱高产分子育种提供种质材料和功能标记，提高品种改良效率。

干旱、高温等非生物逆境是制约小麦生产的主要限制因素，发掘利用优异抗逆基因和种质资源培育抗逆高产小麦新品种是应对环境胁迫的重要途径。茎秆可溶性糖（SWSC）是小麦籽粒灌浆的主要碳源，在逆境胁迫条件下对产量影响巨大。提高小麦SWSC含量不仅能增加产量，还能提高成株期抗逆性。SnRK2是植物特有的蛋白激酶，参与调节SWSC代谢，是培育抗逆作物新品种的重要基因，但生产上未充分利用。本项目拟克隆TaSnRK2，分析基因多态性，发掘优异等位变异，开发功能标记，揭示优异等位基因的时空分布点。本项目全面完成研究任务，实现了预期目标。主要结果如下：.(1) 克隆了TaSnRK2.3的3个拷贝，发现TaSnRK2.3-1A 和TaSnRK2.3-1B均与株高和千粒重显著关联，同时TaSnRK2.3-1B与开花和灌浆期SWSC显著关联。单倍型Hap-1A-1、Hap-1B-1是株高，千粒重优异单倍型，后者还是SWSC优异等位变异，二者在育种中受到了正向选择。.(2) 克隆了TaSnRK2.4的3个拷贝，发现TaSnRK2.4-3A 和TaSnRK2.4-3B均与千粒重显著关联，等位变异SNP3A-T 和SNP3B-C高千粒重优异变异。酵母双杂交和荧光素酶实验证明TaSnRK2.4能与逆境胁迫应答蛋白TaLTP3和磷吸收调节因子TaPHR1互作，说明TaSnRK2.4参与调控磷的吸收。 .(3) 克隆了TaSnRK2.9的3个成员，仅在TaSnRK2.9-5A上发现了3个SNP，基于SNP位点开发了2个KASP标记。TaSnRK2.9-5A在自然群体中存在4种单倍型，其中Hap-5A-1 和Hap-5A-2与千粒重相关，Hap-5A-4与穗粒数相关，优异单倍型Hap-5A-1/2在中国，Hap-5A-1在巴基斯坦和东欧，Hap-5A-4在西欧受到了正向选择。.(4) 克隆了TaSnRK2.10的3个成员。发现它们均参与对多种逆境胁迫的应答，并且在进化上高度保守。转基因发现TaSnRK2.10过表达能显著提高ABA 信号通路基因的表达，并显著增强转基因水稻的抗旱性。蛋白互作发现TaSnRK2.10能与多种蛋白互作。.本项目发表论文5篇，获得国家发明专利3项，为小麦抗逆遗传改良提供优异基因资源及其分子标记，将提升小麦抗逆高产育种水平，为国家粮食安全做贡献。