Genetic Evaluation Of 7 Substitution Lines And Identification Of QTLs Affecting Yield And Fiber Characters In Chromosome 16 In Upland Cotton (Gossipium Hirsutum L.)

Molecular marker technology as a new type of genetic marker system based on DNA has been developed due to the progress of molecular biology rapidly since the mid eighties of the last century. Although there were only a few decade since it was brought birth, molecular marker technique has been widely used in various aspects of crop genetics and breeding, such as in constructing molecular genetic maps, tagging of important agronomic traits etc. It is important to have genetic materials available, such as aneuploid: monosomic, monotelosomic, substitution lines, addition lines etc. In the present study, substitution lines were used to evaluate the association of the chromosome and agronomic traits, then the objective substitution line 16 was selected to detect QTLs responsible for associated agronomic characters using the traditional cytogenetic materials with modern molecular marker technology. The progress has been made in following two aspects: 1. Genetic Evaluation of 7 Substitution Lines Substitution lines of 1, 2, 4, 6, 16, 17, and 18 chromosome of Gossipium barbadense in G. hirsutum standard background, TM-I, were evaluated to be associated with 7 plant morphological, 8 ontogenic traits, 7 yielding capabilities and their components, and 5 fiber qualities. The results revealed that the 7 substitution lines were associated with different agronomic traits, and the same trait was associated with several substitution lines. SubI was associated with more boll numbers /plant, higher seed index and lint index. 3 Abstract low seed cotton yield, lint cotton yield and seed cotton yield/plant, lint cotton yield/plant, high Micronaire value. Sub2 was associated with the low plant height, higher seed and lint indexs, and high Micronaire value. Sub4 was associated with more boll numbers/plant, higher lint index, and high Micronaire value. Sub6 was associated with the low plant height, boll size, seed index, fiber strength, and high Micronaire value. Sub 16 was associated with the low plant height, more fruit branch, the lower 1St fruit-branch node, less days from planting to boll budding and squaring, low boll size, high lint and seed index, low percentage of pre-frosty seed cotton, low seed cotton yield/plant, short fiber length, low fiber strength, little fiber elongation ratio, and high Micronaire value. Subl 7 was associated with more days from planting to boll opening, less boll numbers/plant, low boll size, low seed cotton yield/plant, low lint yield/plant, and high Micronaire value. And Sub 18 was associated with the higher plant height, the higher I ~ fruit-branch node, more days from planting to boll opening, less boll numbers/plant, low boll size, low seed cotton yield/plant, low lint yield/plant, low fiber strength, high fiber elongation ratio, and high Micronaire value. 2. QTL Analysis in Chromosome 16 The above results show that Subl6 was associated with different agronomic traits. To detect QTLs controlling important agronomic traits on chromosome 16, 178 F23 families were developed from an F2 population derived from a cross between TM-I and Sub 16. The major gene plus polygene mixed inheritance model was used to analyze the genetics of the II traits by using one single segregation generation of F2:3. In chromosome 16, th...