Genetic Analysis and QTL Mapping of Fusarium Wilt Resistance In Gossypium barbadense Cotton In China

Fusarium wilt (Fw) is one of the most destructive diseases in cotton in China and most Gossypium barbadense cultivars are susceptible. A mapping population of F₂ (186 plants) derived from an intraspecific G. barbadense cross between resistant ‘06-146’ and susceptible ‘Xinhai 14’ was used for mapping quantitative trait loci (QTLs) for Fw resistance. In this study the susceptible Xinhai 14 was used as a female parent and the resistant 06-146 was selected from a susceptible germplasm and used as male parent. Genetic segregation of Fw resistance based on a visul rating system was analyzed and molecular markers were also developed for the mapping population. The following results were obtained from this study:

1. The additive-dominant effects played a major role in Fw resistance and the broad-sense heritability of average Fw ratings was 74.3% and the narrow-sense heritability was 67.8%.

2. Fw resistance was significantly positively correlated with cotton yield and fiber quality in this segregating population. When severe wilt symptoms exhibited, plants were shorter, and the yield related traits such as fruiting branch, total boll number and boll weight were significantly decreased, and fiber length and strength were also worsened.

3.Of the 122 polymorphic marker loci in the F₂ mapping population, 17 linkage groups covering 10 chromosomes were constructed. The total genetic length was 923.6 cM, which covered 16.6% of the cotton genome with an average genetic distance of 10.7 cM.

4. Three Fw resistance QTLs were found to be located on LG1 (Chr. 26),  LG3,  LG17 (Chr. 8), which explained 33.6%, 2.15% and 21.5% of the phenotypic variation in Fw resistance, respectively.