小麦抗倒伏相关性状QTL定位与优异等位变异发掘

Lodging is one of the major constraints in modern wheat production. It is well known that lodging resistance has been improved efficiently by reducing plant height. But excessive reduction of plant height will lead to the decrease of yield. Hence, how to enhance lodging resistance without further reduction of plant height needs to be resolved urgently in breeding program. Lodging is a quantitative trait, and lodging resistance is very difficult to select in the field. Shi4185, well known for its excellent lodging resistance, is one of the dominant varieties and the most important parents in Yellow and Huai River Reaches Winter Wheat Region. Shi4185 was crossed with Shijiazhuang8, a high-yielding but lodging-sensitive variety, with a similar plant height and grown in the same region as Shi4185, to construct the F7 RIL population. In this project, the RILs will be used to detect QTL related to lodging-resistant traits from Shi4185 under different environments. The QTL identified in Shi4185 will be used as candidate loci to detect possible allelic variation in the natural population by association analysis. As a result, the molecular makers will be developed and used in MAS for lodging resistance improvement in breeding program.

倒伏是制约现代小麦生产的重要因素之一。众所周知，降低株高可以有效提高小麦的抗倒伏性，但过度降秆会影响其产量的发挥。因此，如何在保持现有株高的情况下进一步提高品种的抗倒伏性是育种中亟待解决的问题。倒伏属数量性状，通过常规育种方法很难准确快速地在田间进行评价和选择。石4185是黄淮麦区大面积推广的高产品种和重要骨干亲本，抗倒伏性强，利用石4185与株高相近、丰产性好、但抗倒伏性差的石家庄8号杂交，构建了F7代RIL群体。本项目拟通过对RIL群体多年多点表型鉴定，发掘石4185中与抗倒伏相关的QTL，进而以这些QTL作为候选标记在自然群体中进行关联分析验证，发掘优良等位变异，开发抗倒伏辅助选择分子标记，为小麦抗倒伏育种提供技术支撑。

倒伏是影响小麦生产的重要限制因素之一，它不仅影响小麦的产量，而且严重影响小麦的品质。本项目利用石4185/石家庄8号RIL群体和660K小麦基因芯片，通过分离群体分组法（bulked segregant analysis，BSA）定位5个QTL与木质素含量相关，其中2个QTL在两个环境以上被重复检测，基于这两个QTL（QLC.caas.3B和QLC.caas.7D）开发的KASP标记可初步用于木质素含量分子标记辅助选择。结合多年表型鉴定，获得6个抗倒伏性表现较好的材料可用做育种亲本。采用一组抗倒性较好的品种（系）（石4185、轮选103、轮选163、轮选126、矮抗58、小偃101和周麦18）与另一组抗倒性较差的品种（系）（轮选49、轮选136、中麦875、轮选87和轮选99）对抗倒性相关的13个性状进行分析，两组品种（系）间在株高、第2节间长度、小维管束数目、厚壁组织厚度和茎秆抗折断力5个性状上存在显著差异（P < 0.05）。相关和主成分分析进一步明确株高、第2节间长度和茎秆抗折断力是引起两组品种（系）抗倒性差异的关键性状，这3个性状可作为小麦抗倒伏育种的主要选择指标。通过对黄淮冬麦区近60年大面积推广品种倒伏相关性状遗传进展研究发现，随着育种时期推进，株高、重心高度，第二节间长度和倒数指数呈显著下降趋势，而茎秆抗折断力呈显著上升。株高、重心高度，第二节间长度、倒数指数和茎秆抗折断力遗传进展分别为-0.50cm、-0.27cm、-0.06cm、0.032N和-1.20cm•g/N。另外，克隆了影响小麦木质素合成关键基因Ta-CCR1和TaCM，为后续功能标记开发奠定了基础。通过本项目定位了影响木质素含量的QTL，明确了影响小麦抗倒伏性的关键性状，同时，阐明黄淮冬麦区小麦倒伏性状遗传进展，为更好地提高小麦抗倒性打下坚实基础。