Natural variation in wild Gossypium species as a tool to broaden the genetic base of cultivated cotton

Cotton is the world’s most important natural textile fiber and a significantly growing source of food stuff, oil and feeds. Among the 53 Gossypium species, only 4 are cultivated, with G. hirsutum and G. barbadense comprising over 90% of the total cotton cultivation area worldwide. The extensive use of only a few closely related genotypes of cotton, coupled with the widespread adoption of transgenic cultivars, has greatly reduced the genetic base of the crop. This genetic uniformity makes cotton highly vulnerable to emerging biotic and abiotic challenges. Future breeding targets have to seriously consider infusing novel genetic variation into the gene pool of cultivated cotton that can buffer the crop against agro-environmental challenges brought about by shifts in climate. The wild Gossypium species hold a tremendous amount of untapped genetic diversity that can be exploited to broaden the genetic base of cotton. This review highlights the important agronomic traits that have been reported in wild Gossypium species and discusses the various pre-breeding strategies that have been utilized to incorporate genomes of wild Gossypium in cultivated cotton. Genetic and molecular studies towards understanding Verticillium wilt resistance and salt tolerance in wild cotton relatives are presented in brief.