Genomic insight into the biogeographic history, divergence, and adaptive potential of G. purpurascens, a forgotten landrace of G. hirsutum

Continuous selection and adaptation to the local environment resulted in the loss of genetic variation in Gossypium hirsutum, which is the most important source of natural fiber. Wild progenitors are an excellent source for strengthening the genetic base and accumulation of desirable traits in modern cultivars. Here we reevaluate a landrace of Gossypium hirsutum, formerly known as Gossypium purpurascens. We seek to understand the genomic structure, variation, and the adaptive/breeding potential among largely neglected landraces of Gossypium hirsutum purpurascens, providing insights into the biogeographic history and genomic changes likely associated with domestication. Population fixation statistics suggested marked differentiation between G. purpurascens and current varieties, obsolete accessions, and geographical landraces of upland cotton, emphasizing the divergent behavior of G. purpurascens. Phylogeny established the primitive nature of G. purpurascens, the inclusion of which in upland cotton gene-pool can enhance the narrowed genetic base of upland cultivars. Genome-wide associations comprehend multiple loci associated with domestication regions corresponding to flowering and fiber quality. Moreover, the conserved nature of G. purpurascens can provide insight into understanding the evolutionary process of G. hirsutum.