Association analysis of drought tolerance traits of upland cotton accessions (<italic>Gossypium hirsutum </italic>L<bold>.</bold>)

Abstract

<p indent=0mm>Drought stress is an important factor that leads to severe reduction in cotton fiber yield and quality worldwide, and new cotton varieties with high-yield, high-quality and drought-tolerant characteristics have been the goal for cotton breeding. In this study, 217 upland cotton accessions were selected for drought stress experiments and association study. The drought stress treatment panels were supplied with 50% the water volume of the controls, until the seedlings emerged. A total of 18 traits including agronomic traits, fiber yield indices and fiber quality indices, were investigated at two locations and for two years. After drought stress, there were significant differences in response between populations, and significant differences in phenotypic traits between control and treatments. The phenotypic data were analyzed by BLUP, and the drought resistance coefficient of each trait was calculated. A total of 393 loci were detected by 214 SSR marker in the tested cotton accessions. The average gene diversity coefficient was 0.402, with the range of 0.072–0.631; and the average PIC value was 0.329, ranging from 0.070 to 0.560. Genetic structure analysis showed that the group could be divided into two subgroups and it had no obvious correspondence with geographical origin. There were detected extremely 76 significant loci (<italic>P </italic>< 0.01), with explanation rate ranging from 2.931% to 7.218%, by association study using drought resistance coefficient (DRC) of 18 traits. Fourteen SSR marker could be detected by two or more traits at the same time. These results could provide a theoretical basis and reference for the parents selection and drought-resistant molecular marker-assisted breeding in cotton.