Genetic Mapping Of Br1 Gene And Microscopic Observation Of The Dehiscence Zone Of Rachis Nodes In Tibetan Semi-wild Wheat

Tibetan semi-wild wheat(Triticum aestivum ssp.tibetanum Shao))is a kind of primordial hexaploid wheat sub-species which only grows in Tibetan plateau.It is one of the unique wheat germplasm resources in China and has great value in the study of the classification,origin and evolution of wheat and great potential in the study of wheat genetic breeding and genetic resources.Predecessors' research has to control Tibet half wild wheat crisp panicle traits of gene location on the Tibet half wild wheat chromosomes of 3DS and named as Br1,in order to more accurate positioning for Br1 and study of the control mechanism of the brittle ear,this study used Tibet half wild wheat Q1028(female parent)and Zhengmai 9023(male parent)constructed recombinant inbred lines strain Br53 has carried on the brittle spike traits in investigation,SNP chips scanning,cob section electron microscopic scan and cob tissue biopsies from area,get the following results:1.Through the statistical analysis and chi-square test of the brittle spike characters of the recombinant inbred line F2 and F3,the separation ratios of the brittle and non-brittle were found to be 3:1 and 5:3,it is consistent with the mundell genetic law,indicating that the brittle of Tibetan semi-wild wheat was controlled by a single dominant gene.2.Through scanning 55 K SNP chips for genetic mapping group screening Q1028 and ZM9023 polymorphism,get with 27 SNPS the most closely interlocking in 3DS chromosome polymorphism markers,build Br1 genetic linkage map,and locate the gene on molecular markers between the AX-109395143 and AX-108731997,locate area the scope of the genetic distance of 5.6 cM,candidate genes of area is limited in Chinese spring 3D chromosome 53.23 Mb to 72.70 Mb,and the 3D chromosome of Aegilops tauschii is between 56.39 Mb and 76.12 Mb.The localization results successfully narrowed the Br1 gene to a physical range of 20 Mb.3.Through scanning electron microscope(SEM)to observe the fracture surface of ZM9023 and Br53,and it was found that the section of Br53 was smoother than that of ZM9023,indicating that it could break the ear spontaneously without externalforce in the mature stage and had a tendency to break the ear naturally.4.Through semi-thin slices and paraffin sections were made by longitudinal cutting of the parent material rachis,it was found the "constriction groove" in Tibetan semi-wild wheat but not in ZM9023,indicating that the exfoliation of internode of spike occurred in Tibetan semi-wild wheat in Tibet.In the meantime,it was found that there was no significant difference in lignin content between the two parent material.It can be inferred that the brittle spike of Tibetan semi-wild wheat was not caused by lignification of layer separation,which different from the internode shedding mechanism controlled by q gene.