Construction of ethyl methane sulfonate mutant library in G. arboreum and rapid identification of mutant genes via repeated re-sequencing

Cotton (Gossypium) is the leading economic crop and provides most of renewable spinning fibers for the worldwide textile industry. The diploid Asiatic cotton (G. arboreum), with spinnable fiber and relatively simple genome, is an ideal model for cotton functional genomics and fiber biology. In this study, we constructed an ethyl methane sulfonate (EMS) mutant library of Asiatic cotton. Stable mutants with various phenotypic variations in leaf, flower, fiber and plant architecture were obtained in M1 generation. Genome-wide mutation analysis revealed high-density mutations distributed evenly on whole genome. Using repeated re-sequencing of M1 mutant plants, the candidate genes of 10 out of 15 mutants were identified. The functions of GaYUC4 and GaPDX1, candidate genes for bar blade and yellow leaf vein, respectively, were further confirmed using virus induced gene silencing in Asiatic and/or upland cottons. Our work paved way for expansion of Asiatic cotton mutant library and subsequent applications in cotton functional genomics and cotton breeding.