Development Of Pima Cotton Chromosome Segment Substitution Lines With Gossypium Hirsutum Background And QTL Mapping For Fiber Quality

Upland cotton(Gossypium hirsutum L.) and sea island cotton(G. barbadense L.) are two cultivated tetraploid cotton varieties. Upland cotton is characterized by high fiber yield and moderate fiber quality. Sea island cotton is characterized by low fiber yield, increased fiber fineness, length and strength. Transmission of valuable genes extensively and efficiently between G. hirsutum and G. barbadense is essential for fiber quality of Upland cotton improvements. Chromosome segment substitution lines(CSSLs) is with the exception of one or a few homozygous chromosome segment transferred from a donor parent, the remaining genome of each CSSL line is the same as the recipient parent. It is an ideal material for fiber quality QTL mapping. In the present study, we developed a set of CSSLs, using G. hirsutum CCRI8 as the recipient parent and G. barbadense Pima90-53 as the donor parent, through molecular assisted-selection in BC3F1-3 generations. Fiber quality traits QTLs were mapped by BC3F2 candidate individual population and CSSLs. The main results were summarized as follows:1. The F1 was generated by a cross using upland cotton cultivated variety CCRI8 and sea island cotton Pima90-53. The CCRI8?Pima90-53 F1 progeny were backcrossed with CCRI8 until BC3F1 and self-pollinated to produce BC3F2 and BC3F3. We developed a set of CSSLs with Gossypium hirsutum CCRI8 background through molecular assisted-selection in BC3F1-3 generations.2. The CSSLs consist of 182 different lines. The minimal number of substituted segment is 1, the maximal number is 11, averages 5. The substituted segments of each line in length range from the shortest segment 0.7 c M to the longest 83.2 c M. The average length of subsitituted segments is 21.0 c M. The genetic length of the substituted segments covered 19957.8 c M, 4.7 times the total genetic length of upland cotton(4168.7c M), coverage rate is 96.2%. There are absent segment in the chromosome A7, A12, D2, D7, D12.3. QTL of fiber quality were mapped in BC3F2 candidate individuals and CSSLs with the software QTL Ici Mapping v3.3. There were 26 QTLs for fiber quality traits. There were 9 QTLs with the additive genes from Pima cotton, and 6 QTLs were for fiber length, 1 QTL was for fiber strength, 1 QTL was for micronaire.4. In the present study, we have found 5 CSSLs individuals with excellent fiber length; fiber strength and micronaire. Fiber length and fiber strength of the five materials were above 31.75 mm and 33.18 c N/tex. Micronaire ranged from 3.8 to 4.3.