Gossypium DNA Markers: Types, Numbers, and Uses

Abstract

Numerous DNA marker systems, each with their own advantages and disadvantages, have been described for cotton. Microsatellite markers (also known as simple sequence repeats [SSRs]) are robust and, coupled with their co-dominant expression, make them the current marker of choice for phylogenetic/evolutionary studies, development of genome maps and the identification of DNA markers linked to desirable traits for use in marker-assisted selection (MAS) in cotton. Despite the advances made with such markers, there remains a need for new genomic tools, such as single nucleotide polymorphisms (SNPs), to identify further polymorphism in cotton. The allo-ploidy of the leading cultivated cotton species, together with its widespread dispersal and the selection pressure applied during domestication and scientific improvement, has resulted in a very narrow genetic base. There is thus a need to introgress novel traits from feral or wild relatives, requiring suitable markers for use in MAS. In the future more attention will be devoted to producing consensus genome maps, which will be important if the aim of ‘breeding by design’ is to be realized in cotton improvement.