Identification of new genetic sources of resistance to bacterial blight race 18 in diploid Asiatic cotton and resistance transfer to tetraploid Upland cotton (Gossypium hirsutum)

Bacterial blight (BB) caused by Xanthomonas citri pv. malvacearum (Xcm), poses a significant threat to Upland cotton (Gossypium hirsutum L.) production worldwide, and Xcm race 18 is the most virulent and widespread and can cause serious yield loss. Understanding the genetic basis of resistance in diploid Asiatic cotton (G. arboreum) and successfully transferring the resistance to tetraploid Upland cotton are crucial for developing resistant cotton cultivars. This study aimed to identify chromosomal regions for BB resistance through a genome-wide association study (GWAS) using 245 G. arboreum accessions evaluated in two replicated greenhouse tests and to evaluate an introgression BC2F7 population derived from a tri-species hybrid (G. arboreum/G. aridum/G. hirsutum). In response to Xcm race 18 infections after artificial inoculation, 80