Gene Discovery and Fine Mapping for Heading Date in Common Wheat
|School||Sichuan Agricultural University|
|Course||Biochemistry and Molecular Biology|
|Keywords||common wheat EMS mutants heading date molecular markers comparativegenomics fine mapping|
The optimum flowering time is essential for sustainable productivity and high yield potential of crops, therefore, discovering the heading date genes not only provide the theoretical guidance for the cultivation of varieties adapted to different ecological zones, but also can offer the candidate genes for wheat breeding. In this study, the wheat heading date mutants from the Yanzhan4110EMS libraries were analyzed and the following results were obtained.1. Sixty heading date mutants were selected from the EMS mutant libraries and were grown under the photoperiod and vernalization controlled ambient. Throughout the investigation of the developmental stage, we found that the photoperiod is the main factor to influence on the heading date of the mutants. The important photoperiod gene Ppd-D1was used to detect the sequence variations among the mutants. Five mutants with a single base mutation each were identified. Specifically, M39deleted a C base in the promoter region; M2, M15and M18all happened C/T conversion in the fourth intron region, G insert and T insert respectively; M13occurred C/T conversion in the seventh exon area. These Ppd-D1single base mutations could result in the promoter region of base conversion, amino acid changes and intron regulatory difference. They may be related to the heading date variations of the five heading date mutants.2. In order to map the late heading date gene from M605, we made the cross between the M605and the early heading date variety Mexico Spring47. The F2and F3populations were planted in Shunyi (Beijing) and Xinxiang (Henan province). After the investigation of the agronomic traits of the F2generation, we found that heading date was significant negative correlation with1000-grain weight, grain yield per plant, number of grains per plant, number of grains per spike, number of spikelets per plant, spike length, effective tillers and plant height, in particular,1000-grain weight and number of grains per spike showed the highest negative correlation coefficients. The above results indicated that the heading date seriously affect the wheat production. Using the SSR markers and the F2:3populations, the late heading gene from M605was mapped onto the wheat chromosome3D with the flanking markers barc42and cfd152, with the distance of5.8cM and14.4cM, respectively. In order to narrow down the distance, a batch of new SSR markers were developed based on collinearity among rice, B. distachyon and the D genome draft sequence. Five new markers among them were linked with the heading date gene. The nearest genetic distance was0.2cM. The results will be useful in cloning of the heading date gene M605in the future.