Seed Vigor Identification And Molecular Marker Development Of Upland Cotton Germplasm Resources Under Adversity

Cotton is an important fiber and oil crop in the world.High vigor seeds have strong resistance to adverse environments and obvious growth advantages and production potential.There are often problems of low temperature,drought,salt and alkali stress in Xinjiang cotton region.Therefore,it is of great practical significance to screen cotton germplasm resources with high vitality under different stress conditions for cotton production practice.In this study,the traditional germination method was used to identify the seed vigor of 122 upland cotton resources at germination stage,and a comprehensive evaluation system of seed vigor was constructed to screen out the identification indexes for evaluating seed vigor.The potential candidate genes related to seed vigor traits were used to design molecular markers.According to their genotyping and phenotypic correlation in the tested materials,molecular markers that can evaluate seed vigor were screened.The related work will provide reference for targeted utilization of upland cotton germplasm resources,comprehensive evaluation of seed vigor and molecular marker assisted selection.The main results of this study are as follows:1.Principal component analysis and membership function calculation were carried out on 11 vigor indexes to obtain the comprehensive D value of each conditions under standard condition,various adversity and comprehensive conditions,respectively.The correlation analysis results of each D value showed that the D value under comprehensive conditions was extremely significantly positively correlated with the D values under drought stress,salt stress and artificial aging conditions,and the correlation coefficient was above 0.796.Through the identification and evaluation of seed vigor of upland cotton by comprehensive condition D value,122 upland cotton materials can be divided into five categories: high vigor materials,high vigor materials,medium vigor materials,low vigor materials and low vigor materials.2.A multiple linear stepwise regression model of multiple environments was established,which can be used to select cotton varieties according to the environmental characteristics of various regions.Standard conditions: Q=-0.402+0.617 × SFW+0.008 × GI+0.071 × SSL+0.025 × SRL+1.525 × SDW;low temperature stress: Q=-0.354+0.015 × GI+4.838 × SDW+0.103 × SSL+0.031 × SRL;drought stress: Q=-0.002+0.023×GI+0.335×SFW-0.003×GR+0.073×SSL;salt stress: Q=-0.134+0.030×GI+0.630×SFW+0.086×SSL;artificial aging: Q=-0.330+0.051×SSL+0.003×GP+0.727×SFW;comprehensive conditions: Q=0.243+0.008×GI(SS)+0.008×GI(DS)+1.662×SDW(SS).3.The Q value was evaluated by correlation analysis between Q value and comprehensive D value.The identification indexes under standard conditions were seedling fresh weight,germination index,seedling length,seedling root length and seedling dry weight.The identification indexes under low temperature stress were germination index,seedling dry weight,seedling length and seedling root length.The identification indexes under drought stress were germination index,seedling fresh weight,germination rate and seedling length.The identification indexes under salt stress were germination index,seedling fresh weight and seedling length.The identification indexes under artificial aging conditions were seedling length,germination potential and seedling fresh weight.The identification indexes under comprehensive conditions included germination index and seedling dry weight measured under salt stress,and germination index measured under drought stress.4.According to the published gene and primer information,a pair of dominant molecular markers were developed for the differential genes of cotton seed germination.At the same time,three pairs of EST-SSR and In Del primers were used to genotype 56 randomly selected upland cotton materials with different seed vigor.Combined with the phenotypic correlation analysis among different genotypes,it was found that the correlation degree between the four markers and the variables of the multivariate linear regression model under salt stress and comprehensive conditions was quite different.Among them,the marker SC150924 was significantly correlated with germination index under drought stress,germination index under salt stress,and seedling dry weight under salt stress.Since there is a significant indigenous correlation between the comprehensive D value and the result Q value of the multiple linear regression model,it is speculated that the marker SC150924 may have the potential to evaluate seed vigor under various stress conditions.