Association Analysis Of Yield Traits And Flavonoids Content In Grains With SSR Markers In Tartary Buckwheat Germplasms

In this study,230 tartary buckwheat germplasms were used as materials to evaluate 15 traits including flavonoids content in grains(FC),plant height(PH),branch number of main stem(BN),grain weight per plant(GW),grain number per plant(GN),100-grain weight(100GW),initial flowering stage(IF),full-flowering stage(FF),grain length to width ratio(L/W),grain projectionarea(GA),grain diameter(GD),grain perimeter(GP),grain length(GL),grain width(GWI)and grain yield(GY)in three environments.The major factors influencing grain yield and the flavonoids content in grains were investigated.The excellent tartary buckwheat germplasms were selected with high grain yield and high the flavonoids content in grains.The genetic diversity,population structure and linkage disequilibrium(LD)of tartary buckwheat germplasms were analyzed using 59 polymorphic SSR primer pairs,and the association analysis of these SSRs with the tested traits was performed.The main results were as follows:1.Variation analysis of FC and yield related traits of tartary buckwheat germplasmsEnvironment produced extremely significant effects on the tested traits in tartary buckwheat germplasms expect 100GW,GP and GWI.The variation range of FC in 2018S,2018A and 2019A was 1.37%~2.84%,1.12%~2.81%and 1.08%~2.83%,and the coefficients of variation was12.06%,13.27%and 14.33%respectively,which indicated FC was moderate variation and possessed improved space in tartary buckwheat germplasms.In three environments,FC in registered varieties was significantly higher than that in landraces and breeding lines.FC in yellow-grains germplasms was significantly lower than that in brown-,gray-and black-grains germplasms,indicating that grain color had an effect on FC.In three environments,the coefficient of variation of GW,GN and GY were the largest ranged from 15.24%to 34.53%,indicating that the three traits had a wider variation and possessed more improved space than other yield related traits.The coefficient of variation of GP,GD,IF and FF was the smallest variation ranged from 2.70 to 6.92%,indicating that the genetic improvement of the four traits was difficult.2.The major factors influencing grain yield and the flavonoids content in grainsCorrelation were inconsistent between FC and yield related traits in different environments.FC was significantly positively correlated with GD and GA in 2018A and 2019A,and was significantly negatively correlated with FF in 2018A.GY was significantly positively correlated with PH,GW and GN,and was positively correlated with GA in three environments.the 15 teseted traits could be concentrated into four main factors in the three environments,grain type factor,yield component factor,flowering factor and flavonoid content in grains factor.Thirty-four tartary buckwheat germplasms were screened in three environments by cluster analysis,among which eight germplasms had high flavonoid content in grains,twenty-six germplasms had high grain yield.The thirty-four selected tartary buckwheat germplasm can be used as recommended materials for tartary buckwheat varieties breeding with high yield and quality.3.Genetic diversity analysis of SSR primer pairs in tartary buckwheat germplasmsIn this study,59 SSR primer pairs were used to test the genotype segregation.A total of 254 alleles were identified of 59 SSR primer pairs,with an average of 4.31 alleles and 2.72 effective alleles in per pair.The variation range of Shannon’s information index was 0.04~2.09,with an average of 1.05.The variation range of fixed coefficient was-0.74~0.73,with an average of 0.02.The polymorphic information content ranged from 0.02 to 0.85,with an average of 0.51.The results indicated that 230tartary buckwheat germplasms had a wide range of genetic variation.The genetic similarity coefficient of 230 tartary buckwheat germplasms ranged from 0.102 to 0.983.The 230 tartary buckwheat germplasms were divided into 4 groups at a genetic similarity of 0.650.Principal coordinates analysis showed that 59 SSR primer pairs could effectively distinguish 230 tartary buckwheat germplasms.4.Population structure and LD analysis of tartary buckwheat germplasmsIn 230 tartary buckwheat germplasms,LD was significant at a 0.05level among 44.65%of the 764 SSR pairs.The subgroups POP1 and POP2 accounted for 1.40%and 12.45%respectively of all SSR pairs,which was far less than the number detected in all materials,indicating this group could be used for association analysis.In 230 tartary buckwheat germplasms,the linkage disequilibrium coefficient(r~2)ranged from 0 to 0.984,with an average of 0.128,indicating that the LD had a narrow variation.5.Correlation analysis of SSR markers and FC and yield traits of tartary buckwheatThirty-seven SSR markers were significantly correlated with the 15tested traits in three environments.Among them,13 SSR markers were repeatedly detected in two or more environments,and were significantly associated with two or more traits.They were TatG-110,TatG-172,TatG-210,TatG-185,TatG-212,TatG-101,TatG-057,TatG-032,TatG-250,TatG-027,TatG-206,TatG-015 and FtgGK-67.Therefore,the 13 SSR markers could be verified the corrlation with traits for molecular marker assisted breeding.