Rapid Identification Of Basic Materials And Optimization Of Development System Of K-Type Thermo-Sensitive Line Wheat (Triticum Aestivum L.)

Wheat is an important food crop in China.Heterosis utilization is an important way to realize the rapid development of wheat industry,and breeding photo thermo sensitive male sterile wheat is the core of heterosis utilization of wheat.Thermo sensitive cytoplasmic male sterility with Aegilops Kotschyi cytoplast（K-TCMS）wheat has high critical temperature for fertility conversion,and can be"one system for two purposes"and widely adapt to the ecological conditions of Yellow and Huai River valleys Facultative Wheat Zone,which is the main wheat producing area in China.Therefore,breeding K-TCMS wheat suitable for this area is of great scientific and economic significance.In this study,41 K-type cytoplasmic male sterility（CMS）wheat maintainer lines and 96K-CMS restorer lines collected by my research group were used to screen the molecular markers that can be used for rapid identification of K-TCMS wheat basic materials.In 2019and 2020,292 and 115 wheat lines from all over the country were used as materials to test cross with K-TCMS wheat KTP116A,and a two-year test cross F₁ population was constructed.The accuracy of the screened molecular markers was verified by the match between the fertility identification results of 407 F₁ generations and the PCR detection results of the original male parents.In addition,K-TCMS wheat KTP116A was used as material to carry out tiller regeneration experiment and spring stage sowing experiment,so as to optimize the breeding system and propagation system of K-TCMS wheat.The main results obtained are as follows:1.Rapid identification of K-TCMS basic materialsThe screening result of molecular markers showed that Xnwafu1,Xgwm11 and Xgpw4313displayed stable polymorphism in 96 restorer lines and 41 maintainer lines.The discrimination between maintainer lines and restorer lines of K-CMS material was higher than 90%.The statistics of selfed seed setting rate of F₁ generation and the PCR detection results of original parents showed that the matching degrees of Xnwafu1,Xgwm11 and Xgpw4313 markers are77.40%,79.45%and 78.77%respectively in 2019,66.96%,69.57%and 71.30%respectively in 2020.The total matching degrees of Xnwafu1,Xgwm11 and Xgpw4313 are 82.53%and73.04%in 2019 and 2020 respectively.Therefore,Xnwafu1,Xgwm11 and Xgpw4313 are excellent molecular markers for rapid identification of basic materials of K-TCMS lines.2.Optimization of K-TCMS breeding systemTaking K-TCMS wheat KTP116A as material,the experiment of tiller regeneration was carried out to optimize the rapid breeding system of K-TCMS wheat.The results showed that the best ear cutting system was topdressing at booting stage,cutting ears by retaining whole leaves at heading stage and removing primary tillers again after 7 days.However,there is no significant difference among the three topdressing periods under the ear cutting method of retaining the whole leaves at heading stage.For the consideration of technical system integration,the ear can be cut by retaining the whole leaf at heading stage and irrigated and fertilized on the day of ear cutting to reduce the workload.3.Optimization of K-TCMS propagation systemK-TCMS wheat KTP116A was used as the experimental material to sow by stages from February to March 2020 and February to March 2021 respectively.The optimal sowing date was selected according to the seed setting rate,so as to optimize the breeding system of K-TCMS wheat.The research showed that the optimal sowing date of K-TCMS Wheat in Yangling,China was around March 3 of each year.The research results provide technical support for the establishment of K-TCMS wheat breeding and production system,and have important application value for the R&D and utilization of commercial breeding of hybrid wheat.