Dissertation > Agricultural Sciences > Crop > Economic crops > Fiber crops > Cotton

Screening Stamen Development Heat-Tolerance Germplasm and Association Analysis of Agronomic Traits with SSR Makers in Upland Cotton

Author BoAiMin
Tutor TangCanMing
School Nanjing Agricultural College
Course Crop Genetics and Breeding
Keywords Upland cotton(G. hirsutum L.) Stamen development Heat-tolerance Yield Fiber quality Association analysis
CLC S562
Type Master's thesis
Year 2010
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Cotton is the most important textile fiber crop and the second-most important oil crop. Cotton is sesentive to high temperature during the stamea development. In the Yangtze River valley, unexpected periodic episodes of extrme heat stress usually occour in July and August, the peak time of cotton flowering and boll loading, resulting in the reduction of yield. Screening heat-tolerance cotton germplasm was a urgent breeding program in the current and future warmer weather conditions. Association analysis was an effective method for decting QTLs based on linkage disequilibrium (LD). The genotyping data of forty-seven simple-sequence repeat(SSR) makers on 227 cotton varieties (lines) were used to analysis the population structure. By using TASSEL GLM (general linear model) program, the association analysis between SSR loci and traits was performed.1. The mean germination rate was NT30PG(57.78%)> HT30PG(24.97%)> NT40PG(12.60%)> HT40PG(10.05%), there was significant difference between varieties (lines); The mean value of three class heat-tolerance index were 0.44 (type I), 0.21 (typeⅡ) and 0.39(typeⅢ). Based on pollen germination rate and heat-tolerance index, all materials were screened, and 10 and 8 heat-tolerantce varieties were selected respectively. Integrated two types of screening results,5 heat-tolerance germplasm resources (FJA,9650, Yiluzao3, Zhongmiansuo24 and Sumian12) were selected. These materials can be used as core parents for breeding heat-tolerance varieties in cotton.2. Population structure analysis showed that all materials can be divided into eight subgroups. Allele-frequence divergence among groups was between 0.0875 and 0.2219. The pairwise Fst among groups was between 0.0046 and 0.1561. Nineteen SSR loci associated with traits were screened out from this population in total. Twelve SSR loci associated with yield traits, four loci associated with at least two yield traits. Six loci associated with five fiber quality traits, and two loci associated with two fiber quality traits. Compared with the current results about association analysis for cotton, only one loci(BNL1604) correlated with lint percent was same. Four loci associated with pollen germation traits, three loci associated with heat-tolerance index, each loci associated with one pollen germination or heat-tolerance index. There were some loci associated with two or more traits simultaneously, which might be contributed to the correlation among traits or pleiotropic gene.

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