ABSTRACT

Cotton (Gossypium spp.) is one of the most important natural bers and edible oil crops in the world. Upland cotton (G. hirsutum L.), with its high yield properties, accounts for about 95% of annual worldwide cotton production; the extra-long staple (ELS) or Pima cotton (G. barbadense L.), which has superior quality ber properties, accounts for the other 5%. The two tetraploid species are allotetraploids (2n = 4x = 52) composed of two ancestral genomes designated A-subgenome (hereafter At) G. herbaceum and D-subgenome (hereafter Dt) G. raimondi, originating from a polyploidy event ~1-2 million years ago (Wendel and Cronn 2003).