Chromosomal Analysis Of Related Genes And Identification Of Pre-harvest Sprouting Resistance In The Hybrids Between Aegilops Tauschii And Wheat

As an important food crop,wheat is the primary source of nutrients for about 40% of the populations in the world.However,the popular phenomena of wheat pre-harvest sprouting(PHS)leaded to a sharp decline in its yield and quality.Therefore,it is one of the main goals of wheat genetic improvement to screen and identify the PHS resistance gene or germ resources.In this study,we choose the BC2F5 population(832 strains)derived from the crossing of the bread wheat cultivar Zhoumai18 with high yield,wide adaptability and good comprehensive agromic characters and Aegilops tauschii accession T093 with high resistance of PHS native to Henan province of China as the materials,in order to screen some valuable resources with strong PHS resistance and identify some relevant candidate gene loci of PHS,the PHS resistant ability of BC2F5 population were detected through the whole spike germination rate(SGR),the germination index(GI),seed germination and skin identification,and the genetic diversity among bread wheat cultivar Zhoumai18 and Aegilops tauschii accession T093 as well as the representative strains with strong or weak PHS resistance were mainly analyzed by SSR markers.In addition,the distribution of the STS marker of Vp1B3 and TaDFRBb which were generally suggested to be respectively associated with PHS resistance and Red grains also were verified.The results were as follows:(1)20 materials with highly resistance(the 5d germination rates were all less than 10%)to pre-harvest sprouting were selected by the whole spike and seeded germination experiments in two years(2013 and 2014).The studies on the correlation showed that there was a very significant positive correlation between the germination index(GI)and germination rate and which were the effective index to evaluate the PHS resistance of wheat.(2)According to the published map of D genome chromosome,1114 pairs of primers of SSR markers were selected to analyze the polymorphism of the parents(T093 and Zhoumai18)of BC2F5 population,and 405 pairs of primers were polymorphic and further used to analyze the genetic diversity among the parents,8 and 3 strains of BC2F6 population with strong(10%?GI?18%)and weak(GI?331%)resistance to PHS.It was found that the six primers respectively located on chromosome 5DL(Xbarc347,Xgwm182,Xgwm174)and 6DS(Xcfd213a,Xgwm469,Xcfd132)not only could be amplified the bands representative of the fragments imported from Aegilops tauschii T093 but also only occurred in the strains with strong resistance to PHS while were absent in the strains with weak resistance to PHS.Therefore,it was suggested that there must be two candidate gene loci linked with the above six SSR markers were correlated to the resistance to PHS.(3)Analysis of the distribution of the markers Vp1B3 and TaDFRBb showed that the same fragments were amplified in all the 13 strains with different resistance to PHS.Therefore,it was suggested that the candidate loci of resistance to PHS found in this work were not associated with the two known markers.