新型抗白粉病小麦-黑麦6RL小片段易位系的创制及其补偿性研究

The long arm of rye 6R chromosome (6RL) carries resistant gene to wheat powdery mildew, and it is still resistant to many powdery mildew races. An effect way to utilizing this resistant gene is to create small segment translocation lines with good compensation. However, this problem has not been resolved. Supported by the last National Natural Science Foundation, the wheat-rye 6RL minichromosome addition lines were irradiated and wheat-rye small segment translocation line 16T379-8 with powdery mildew resistance was obtained. Line 16T379-8 contains small segment translocation chromosomes 6DS/6RL and 6DL/6RLʹ. In this project, new wheat-rye small segment translocation lines and new wheat germplasms with powdery mildew resistance will be created using line 16T379-8 to cross with ph1b mutant wheat cultivar Westonia and other powdery mildew susceptible wheat cultivars. Wheat cultivar Westonia is also susceptible to powdery mildew. In addition, methods including ND-FISH, molecular marker, MSAP and sequencing will be used to investigate the structure of new small segment translocation chromosomes and the genetic diversity of small segment translocation lines. Furthermore, the multiple agronomic traits of these small segment translocation lines will be investigated to select the ones with good compensation. The aim of this project is trying to use the powdery mildew resistant gene on 6RL to improve wheat cultivars in agricultural practices, to preliminarily reveal how the structure of small segment translocation chromosomes and wheat backgrounds affect the compensation of the translocation lines, and to provide theory references for the creation of wheat-alien small segment translocation lines with good compensation.

黑麦6R染色体长臂 (6RL) 携带的小麦白粉病抗性基因目前仍具抗性。创制具良好补偿性的小片段易位系是利用该抗性基因的有效途径，但这一问题尚未解决。在前期自然科学基金的资助下，我们对抗白粉病的小麦‒黑麦6RL微小染色体附加系进行辐射，并从辐射后代中筛选到了抗白粉病的、含6DS/6RL和6DL/6RLʹ小片段易位染色体的易位系16T379-8。本项目将用这一易位系与感白粉病的ph1b突变小麦品种Westonia以及其它多种感白粉病小麦品种杂交，继续创制新型小麦‒黑麦6RL小片段易位系和一批抗白粉病新种质。进而利用ND-FISH、分子标记、MSAP和测序等技术，研究不同小片段易位染色体的结构及其所处的小麦遗传背景的差异，然后结合多个农艺性状考察，筛选具有较好补偿性的抗白粉病小片段易位系。本研究旨在实现6RL抗白粉病基因的成功应用，初步明确小片段易位染色体结构和遗传背景如何影响易位系的补偿性。

白粉病是小麦重要病害之一，黑麦6R染色体上携带的白粉病抗性基因目前仍具广谱抗性。由于连锁累赘和遗传不平衡的影响，这些抗病基因还未被成功应用。本项目利用抗白粉病的、6R来源不同的小麦-黑麦6R微小染色体附加系和6RL单端体附加系，创制具良好补偿性的小麦-黑麦6R小片段易位系。明确了6R微小染色体包含6RS端部区域、6RL臂间区域和着丝粒区域。利用微小染色体创制小片段易位染色体6DS.6DL-6RL和6DL-6RS-6RL，确定6DS.6DL-6RL为近端着丝粒染色体，包含整个6D染色体短臂和一小段长臂区域，不含白粉病抗性基因。6DL-6RS-6RL为端着丝粒（黑麦着丝粒）染色体，包含一段6D染色体长臂、6RS端部37-42Mbp区域和6RL臂间860-907Mbp区域，该易位染色体携带来自6RS的白粉病抗性基因，该基因编码序列含2866个碱基，其氨基酸序列与Pm21基因编码的氨基酸序列达82.5%相似。在小麦-黑麦5R(5B)二体代换系背景中，6DL-6RS-6RL与小麦3A、4A、2D、5D、7D染色体发生新的易位，发生新易位的频率为1.21%，而6DS.6DL-6RL没有发生再重组。从6RL单端体附加系辐射后代中，鉴定出了抗白粉病的、农艺性状补偿性良好的6BS.6BL-6RL小片段易系。该易位染色体中，6BL缺失区段约为5.3Mbp，包含262个高可信度基因。参与易位的6RL区段约为100.6Mbp，包含875个高可信度基因，与小麦第3和第7同源群染色体具有很好的共线性和高度的同源性。6RL区段上的基因表达存在剂量效应。还鉴定到了抗白粉病的6RL-6DS.6DL小片段易位系。确定了黑麦5R染色体携带条锈病抗性基因的区段。该项目研究结果为成功应用6R携带的抗病基因提供了条件，为诱导小麦部分同源重组提供了新的思考，为创制具良好补偿性的小麦-异源易位染色体提供了新的理论参考。