Genetic Effect Of Hybrid Cotton And The Relationship Between Gene Differential Expression And Heterosis

Pest-resistant transgenic hybrid cottons were widely welcome by cotton fanners, because of whose remarkable yield heterosis and pest-resistance property. The performances and genetic mechanisms of heterosis have become a study hotspot. The genetic effects of yield and quality traits and the interaction between heterosis expression and environment in pest-resistant transgenic hybrid cotton were analyzed under 3 kinds of ecological environments by genetic models with additive-dominant xenvironment(ADE), and heterosis mechanism was also primarily studied in gene differential expression level for the first time by DDRT-PCR (Differential display reverse transcription-polyase chain reaction) in cotton. These results will provide some academic references for pest-resistant hybrid cotton breeding, and accumulate some useful data on explaining biological basis of heterosis. The main results were as follows:Yield traits surpassing parent heterosis in transgenic hybrid cotton were widely existed under various ecological environment, among which heterosis, lint and seed cotton yield heterosis were higher, and followed by number boll. Under high production level environment, hybrids and their parents had higher yield level, but heterosis was not evident, and under relatively low production level, hybrids had relatively lower yield level, but heterosis was significant, indicated that hybrids yield performances were relatively stable in 3 kinds of environments, and parental yield were greatly affected by environment. Fiber quality traits varied with environmental change, but surpassing parent heterosis was not significant. Correlation analysis showed boll number had the closest relation with lint yield. There was a significant positive correlation among boll number, boll size and lint percentage, which indicated the three yield traits may be synchronously improved through parents selection. Correlation was inconsistent between fiber quality traits, and micronaire was a significantly positive correlation with other fiber traits, so it was attached importance to selecting low value micronaire materials in high yield and fine quality hybrid breeding.Boll size, lint percentage, lint yield, elongation, 2.5% span length, strength and micronaire were mainly controlled by genetic main effects, and seed cotton yield, boll number and micronaire were evidently affected by environmental effects. Among these genetic main effects, dominant effect values in 4 yield traits were more than additive effect value, except boll size, and 5 fiber quality traits showed contrary effect, indicated more yield traits exhibited heterosis. Hpm (population heterosis over parent mean), Hpb(population heterosis over parent better) and environment interaction showed lint yield and lint percentage had a better stability, and worse stability displayed in seed cotton yield and boll number. Interaction effect values between yield traits and environment were higher, and lower between fiber quality traits and environment, revealed fiber quality traits can be improved through selection in certain environment, and yield trait should be improved in different ecological environment. The genotype value and heterosis of every F₁ cross yield traits analysis showed that crosses P6×P10, P6×P10 and P6×P10...