小麦-簇毛麦T2VL.2DS易位系抗纹枯病遗传效应分析与新种质创制

Sharp eyespot is a major fungal disease of wheat caused by Rhizoctonia cerealis in cool and humid environments worldwide. The wheat genetic germplasm resistant to sharp eyespot is serious shortage that lead to slowly progressing in breeding resistance cultivars. Exploring the alien resistance genes from the wild species of wheat is therefore important for wheat improvement in this disease resistance. It has been known that Dasypyrum villosum, a wild species of common wheat with genome VV, presented the excellent resistance to sharp eyespot. Sixteen whole-arm wheat-D.villosum translocation lines covering the whole V genome have been evaluated their resistance to sharp eyespot in five consecutive years. The results showed that T2VL.2DS translocation line had an outstanding resistance to sharp eyespot indicating there may be a major resistance gene located on chromosome arm 2VL. In the present project, we will induce 2VL chromosome recombinants using the CS ph1b mutant and develop the small-alien translocated lines or introgression lines, as well as the chromosome arm 2VL will be physically mapped by utilizing the wheat 55K SNP chip and 96 2VL-specific STS molecular markers to screen the small-alien translocated lines. Furthermore, we will also analyze the genetic effects of chromosome arm 2VL resistant to sharp eyespot and other major traits related to yield by introducing the T2VL.2DS translocated chromosome into different wheat varieties. The project results will be beneficial to accelerate the development of the new variety resistant to sharp eyespot in wheat by using the alien sharp eyespot resistance gene of Dasypyrum vollosum.

抗源匮乏是目前小麦抗纹枯病育种进展缓慢的主要原因，从野生近缘种发掘优异抗病新基因是解决这一难题的重要途径。鉴定发现小麦-簇毛麦T2VL.2DS易位系对纹枯病呈现良好的稳定抗性，且抗病基因位于2VL染色体臂上。为了深入分析该抗纹枯病基因的育种利用价值，创制便于育种利用的抗病新种质，本项目拟通过回交转育，分析T2VL.2DS易位染色体在不同遗传背景、不同地点对纹枯病抗性及主要农艺性状的遗传效应；利用中国春Ph1基因缺失突变体，诱导簇毛麦2VL染色体结构变异，创制小片段易位系或渐渗系，明确携带不同2VL染色质片段的各个易位系材料的纹枯病抗性及农艺性状表现；利用小麦55K SNP芯片和STS标记分析小片段易位系或渐渗系，构建2VL染色体臂物理图谱并定位纹枯病抗性基因；选育遗传稳定、不含连锁累赘的抗病小片段易位系或渐渗系，并开发可追踪外源染色体片段的KASP分子标记，为小麦抗纹枯病育种提供新种质。

小麦纹枯病是一种危害小麦茎基部的土传真菌病害，近年来在我国长江中下游和黄淮麦区发生日趋严重，限制了小麦的高产稳产。当前生产上推广品种对纹枯病的抗性普遍较差且抗病育种进展缓慢，究其主要原因是纹枯病抗源匮乏。而研究表明小麦近缘种属中蕴藏丰富抗源。对一套中国春背景的小麦-簇毛麦1V-7V代换系和易位系连续5年2点纹枯病抗性鉴定，发现T2DS.2VL易位系对纹枯病具有稳定抗性。将T2DS.2VL易位染色体通过连续回交方式转入栽培品种矮抗58背景中，发现其提高了纹枯病抗性，且增加穗长的同时对主要农艺性状无不良影响。对T2DS.2VL易位染色体进行流式细胞术分选测序，得到2VL染色体臂384.30 Mb的组装序列，注释了8836个基因，其中6154个基因与普通小麦2AL、2BL、2DL注释基因同源，1549个基因为2VL特有。2VL与普通小麦2DL同源基因间约有10万个SNP差异位点，根据其差异设计了KASP和COS标记，可追踪普通小麦背景中的2VL染色质。通过对接种纹枯病前后的T2DS.2VL易位系进行转录组分析，鉴定到位于2VL染色体臂的64个基因参与了抗病反应，且二萜类生物合成通路显著富集。利用不同来源硬粒小麦-簇毛麦双二倍体构建F2遗传分离群体，结合小麦55K SNP芯片基因分型，构建了2V染色体长约111.4 cM的遗传图谱。利用ph1b基因突变体和Co60-r射线辐射花粉诱导方法，创制了2V染色体结构变异体，结合8个2V染色体特异分子标记，建立了簇毛麦2V染色体物理图谱，进一步结合纹枯病初步鉴定，将2VL携带的抗纹枯病基因物理定位于FL 0.76-1.00区间。研究还利用不同来源簇毛麦2VL染色体臂向普通小麦渗入，创制了小麦-簇毛麦T2DS.2VL#5和T2BS.2VL#5两个新型易位系，为发掘不同来源簇毛麦2VL染色体臂上的优异基因提供了新种质。

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