小麦低温敏感基因wchs1的遗传图谱构建、精细定位和克隆

Freezing temperature limits the geographical distribution of wheat (T. aestivum L.) and often causes severe losses in productivity. Therefore, understanding the genetic mechanism responding to low temperature is very important for wheat tolerance breeding. We characterized a wheat chilling-sensitive mutant BN044371, which carries a chilling-sensitive recessive gene temporarily named wchs1.This mutant grew normally at 3°C and above but showed yellowish and collapsed leaves phenotypes when shifted to temperatures below 0- 2°C after seven or more days at seedling stage. The wchs1 was mapped on the 1DS according to the SSR and SNP markers. In this proposal, next generation sequencing (NGS) and bulked segregant analysis (BSA) techniques were applied to develop polymorphic SNP markers tightly linked to wchs1, a high-density genetic linkage map of wchs1 will be constructed which is essential for fine mapping and map-based cloning of the gene. Based on the advanced genome sequencing of Aegilops tauschii and wheat, using map-based gene cloning technology combining with the gene capture array and the NGS, the wchs1 gene will be cloned. The proposed research will interpret the genetic mechanism responding to low temperature, which is necessary for wheat tolerance theory and breeding practice. The methodology applied in this research will demonstrate its potential power in developing high density genetic linkage maps of agronomical important traits, fine mapping and cloning genes in common wheat.

低温危害一直是小麦生产发展的重要限制因子，关于小麦冻害涉及的生理生化机理有一定研究，但在低温冻害遗传基础及其相关基因方面的研究较少。本项目以课题组发现鉴定的低温敏感突变体BN044371为材料，在前期对低温敏感基因wchs1（暂定名）定位的基础上，应用下一代转录组测序技术（NGS）和集群分离分析（BSA）相结合的BSA RNA-Seq 方法，开发与wchs1 紧密连锁的分子标记，构建高密度遗传连锁图谱并精细定位。结合粗山羊草参考基因组和普通小麦测序信息最新进展，应用图位克隆技术，结合gene capture技术和NGS，实现对wchs1的克隆。研究结果将有助于解析小麦苗期对低温敏感的遗传基础，对小麦抗低温育种理论和实践均具有重要的意义。研究方法和策略对普通小麦D基因组重要性状功能基因遗传图谱构建、精细定位和基因克隆有重要借鉴和参考价值。

苗期和拔节期低温是严重影响和制约小麦（Triticum aestivum L.）生产的主要气象灾害之一，每年都有部分地块不同程度地发生冻害和倒春寒危害。例如，1987 年11 月26 日山东省气温降至- 10 ℃以下，全省超过66.7 万公顷 的麦田受冻，其中10万公顷 绝收，约减产10 亿公斤。因此，低温危害一直是小麦生产发展亟待解决的重要问题，也是小麦抗逆性研究的热点。小麦突变体BN044371的叶片对低温非常敏感，苗期至拔节前期在3±1℃条件下7天左右其叶片开始变黄，进而坏死。显微观察发现其变黄部分叶片表皮细胞表面发生明显的皱缩塌陷，叶片叶肉细胞内液泡发生破裂，叶绿体开始发生解体，但细胞壁结构没有发生显著变化。低温条件下该突变体叶片Fv/Fm显著降低。遗传分析表明该性状受隐性单核基因（wchs1）控制。利用分子标记将该基因定位于1DS染色体0-10Mb物理区间，根据分子标记定位数据和代谢组分析结果，推测候选基因为TraesCS1D01G001600、TraesCS1D01G004500、TraesCS1D01G005400和TraesCS1D01G017700。.研究结果将有助于揭示小麦低温危害遗传基础、理解低温危害机理和抗冻小麦新品种培育。.