Study On Genetic Mechanism Of BNS Male Sterility And Primary Localization Its QTLs In Wheat (Triticum Aestivum L.)

BNS(Bai-Nong Sterility)is a new type of wheat male sterile line,which has good sterility and convertibility by itself,and is of important value in the utilization of wheat heterosis.In order to study the sterile mechanism of this sterile line,in this paper,the genetic mechanism of BNS was detected by analyzing the fertility segregation of hybrids between BNS and fertile wheat varieties,and the QTLs of sterile gene was preliminarily located by the method of.SSR molecular markers.The main results are as follows:1.When BNS be reciprocal crossed with fertile wheat varieties,the self-seed setting rate in Fi generation was low in the combination of BNS as female parent,and increased in the combination of BNS as father parent Although the seed settling rate in some reciprocal cross recombination was increased,it did not reach the level of father parent These results tell us that BNS was nuclear heredity,and some combination genetic background could influence on the sterility of the line;2.When BNS crossed with 455 wheat varieties,in Fi,the percentages of higher infertility combinations that had self-seed setting rate as low as BNS were 15,42%,and high recovery combinations that had self-seed setting rate as high as father vareties were 0.88%.The other combinations were partial infertility,inclining to infertile type.These results showed that BNS sterility has dominant characteristics.At the same times,there were fertile recovery combinations in Fi,suggesting that there was(were)restorer gene(s)in father varieties.On the contrary,in the completely sterile combinations in Fi there must be no restorer gene(s)in father varieties.These results suggested that the sterility and recovery of BNS are the mechanism of non-allelic inheritance.They have loci themselves;3.According to the source of BNS and the fertility segregation in F2 which come from sterile combinations,it is speculated that BNS has two pairs of major sterility genes.Based to the hypothesis of 2 pairs of sterile genes and 2 pairs of restorer genes that was detected in previous study,BNS' genetic mechanism were tested in the generations of 8 F2 generations and 6 backcross offspring.The results showed that the observed values of the separation ratio of sterile plants to fertile plants coincided with the theoretical expectation,indicating that the dominant sterility and non-allelic recover pattern of BNS inheritance were valid;4.The fertility of Fi generation crossed BNS with Zhengmai 366 were completely infertile.So their F2 was used as mapping population to detect QTLs of sterile gene(s).Two pairs of BSA phenotypic pools were established in F2 population.And 710 SSR loci were selected from on the SSR linkage map of wheat,and polymorphic markers were screened by the method of BSA.A total of 12 SSR polymorphic markers linked to male sterile gene were screened from parents and two pools,and which were Xbarc55(lB/2B),Xgwml24(lB),Xwmc658(2A),Xwmc332(2B),Xwmc617(4A/4B),Xwmc752(5A),Xwmc795(5A),Xcfd5(5B),Xbarc267(7B),Xwmc517(7B),Xwmc396(7B)and Xwmc506(7D)respectively.These 12 linkage markers were then used to detect markers separation in the F2 mapping population,and 3 QTLs were found on 2 chromosomes,2B and 7B;5.When 12 pairs of important SSR marker were amplified in parental DNA,24 product fragments were obtained.These fragments were sequenced,and then were blasted in wheat genome databases of Chinese Spring and AK 58 to test the SSR linkage groups.The results showed that 5 were positive for product sequence alignment of SSR,and 7 were negative for.In the 5 positive comparison results,4 positions were chonsisrent with the SSR map,and the other one,Xwmc332,was on 5A,not on 2B.According to the modified linkage relationship,the map distances and QTLs were recalculated and 2 QTLs were detected on 5A.The results also indicate that Xwmc332 is an important linkage marker of stertility genes.Based on the origin of BNS,it was inferred that there were 2 pairs of main genes for BNS sterility,and 2-3 pairs of sterile genes are estimated by F2 population of sterile combination.According to the localization results of QTL analysis,in this paper these 2 pairs of sterile genes were the locus located on chromosomes 7B and 5A,which laid a good foundation for further fine localization of sterile genes.