Genetic Effects Analysis In Upland Cotton(Gossypium Hirsutum.L) And Heterosis Prediction By Yield Related Markers

Developing a fast method to predict heterosis in Upland cotton will have a great significance to efficiently produce hybrids with high heterotic vigor to further improve cotton yield.The objectives of this study were to analysis genetic effects and heterosis in intraspecific hybrid of upland cotton,estimate genetic distance used yield-related SSR markers which previously reported,to determine the relationship with heterosis.11 inbred lines preserved by our group and 30 intra-hirsutum hybrids from a5×6 diallel cross were grown in three major cotton belt regions in northwest inland,yellow river and yangtze river during 2016 and 2017,and the resulting cotton yield,component trait and fiber quality data were evaluated for genetic effects and heterosis used a ADE model provided by Jun Zhu.And valuated the relationship between heterosis and genetic distance?GD?based on yield-trait quantitative trait loci?QTL?related SSR?Simple Sequence Repeats,SSR?markers.Moreover,Pollen viability were detected using Benzidine-?-Naphthol method,analyzed the correlation between fertile pollen rate and yield,fiber quality traits of 48 F₁ hybrids crossed by 12 male sterile Lines and 4 restorer Lines.Mean results as follows:1.Significant heterosis for yield and fiber quality traits were detected in this study,seed cotton and lint yield heterosis were higher than boll weight,boll number per plant and lint percentage,fiber quality traits were lower than yield-related traits.Yield and fiber quality traits for cotton hybrids were both controlled by the main genetic effects and interaction effects of environment,boll weight,boll number,seed and lint yield were found to be mainly controlled by the interaction effect of genetics and environment and dominant effects were higher than additive effects,whereas lint percentage and fiber quality were mostly determined by the main effect of genetics and additive effects were higher than dominant effects.Indicating that yield traits have high heterosis capacity.Seed and lint yield,which were significantly positively correlated with boll weight,boll number and lint percentage,was slightly positively correlated with length,uniformity,micronaire and elongation and slightly negatively correlated with fiber strength.Fiber traits,except for micronaire,were all positively correlated with one another,micronaire was negative with other fiber traits.2.The GD was estimated using 33 stable polymorphic SSR markers selected from a total of 354SSRs for 523 yield and yield trait QTL.The range of parental genetic distance was 0.0783-0.9844.Correlation analysis shows that there are no significant correlation between genetic distance and heterosis in most traits,and just a significant correlation between genetic distance and better parent heterosis?BPH?for seedcotton yield,lint yield and boll number per plant was observed in one location and for boll weight in two other locations.The relationship is a parabolic relation for boll number per plant and a line relation for yield.The genetic distance is ineffective in predicting heterosis in multiple environments,and effective in predicting heterosis in one environment or the materials which insensitive to environment.3.The viability of pollen decreased with the increase of storage time at-20?,above 88%within51 hours.Under this experimental method,the determination of pollen stored at-20?for 51 hours has no significant effect on the results of experiment.The fertile pollen rate of F₁ hybrids were lower than their restorer lines and conventional hybrids,the lowering level of most combinations were less than20%.The restoring ability of restorer lines was obviously different,among which H46 had stronger restoring ability.The relationship between fertile pollen rate and boll number per plant was significant positive,negative correlation with uniformity index reached a significant level of 0.1,the rate of fertile pollen was positively correlated with lint percentage,boll weight,seed cotton yield,lint yield,fiber length,fiber strength,micronaire and elongation,but not significant.