Mapping QTLs For Kernel Traits And Seedling Root Traits In Tibet Semi-wild Wheat

As a primitive hexaploid wheat resource distributed only in Tibet,Tibetan semi-wild wheat(Triticum aestivum ssp.tibetanum Shao)possesses unique characteristics such as tolerance to nutrition deficiency and strong seed dormancy with great potential being exploited in wheat breeding program.Thus,identification and the utilization of desirable genes from Tibetan semi-wild wheat could be important to develop modern wheat cultivars.In this study,a recombinant inbred line(RIL)population derived from a cross between Zhengmai 9023(ZM9023)and Tibetan semi-wild wheat(Q1028),was used to identify QTLsfor kerneland root traits.The main resultsare as follows:1.Genetic analysis of kernel length(KL),kernel width(KW),kernel thickness(KT),aspect ratio(KL/KT)and grain size(GS)was conducted in three years' environment.Totally,thirty-three QTLs were detected,and theywere distributedonchromosomelB,2B(4),2D(9),3A,3B,4A(3),5B(3),6A(3),6B,7A(7),explaning4.64%to 14.69%of phenotypic variance.The positive alleles of the ten QTLs were contributed by Q1028.In addition,seven genomic regions with plenty of QTLs were detected on chromosome 2B,2D,4A,5B,6A,7A.In the present study,the QTL on chromosome and enrichment region is closely related to the grain traits,worthy of attention in breeding program.The region betweenwPt-3561 and wPt-6932 markers on chromosome 2B had QTLs controlling kernel length(KL),kernel width(KW),kernel thickness(KT)and grain size(GS).The region between wPt-671700 and gpw8003markers on chromosome 2D had QTLs controlling kernel width(KW),kernel thickness(KT)and grain size(GS).2.A total of 30 QTLs for seedling root traits on 11 chromosomes were detected.The phenotypic variation explained by each of these QTLs ranges from 6.19 to 18.79%.Positive alleles of 14 QTLs were derived from Q1028.Novel QTLs for root traitswere identified.Co-located and closely linked QTLs controlling different root traits were also detected.In addition,significant correlations were detected amongst most of root traits.Tibetan semi-wild wheat showed significant advantages in tolerance to drought.And six genomic regions with plenty of QTL were detected on chromosome 1A(2),3A,6B(2),7A(2).The regions between wPt-5776 and wPt-667835 markers on chromosome 1A,between wPt-6074 and gwml35markers on chromosome 1A,and between wPt-2564 and wPt-8183 markers onchromosome6Ball had QTLs controlling total root length(TRL)and root surface area(SA),the total root length(TRL)and surface area(SA).Taken together,the results reported here combined with those from previous studies suggested that Tibetan semi-wild wheat could be used as a valuable gene resource in breeding wheat.