Revision of the genetics of the hairiness-smoothness system of Gossypium

The density of pubescence on the abaxial surfaces of leaves of Gossypium spp. (cotton) can range from more than 20 trichomes per 1 cm transect to zero. Several alleles regulating the density of pubescence have been reported. In the past Sm and sm have been used, respectively, to symbolize alleles promoting glabrousness and the pubescent alternatives, and the symbols H and h to denote alleles enhancing the density of pubescence and less pubescent and glabrous alternatives. Recently, precise genetical relationships between alleles that enhance the density of pubescence and alleles that diminish pubescence have been documented. The need for a revision of the genetics of the hairlness-smoothness system of Gossypium thus became apparent. The symbols T and t, denoting trichomes, replace the earlier symbols. Five loci were identified, the t1 locus bearing at least six alleles, the t2 locus six, the t3 locus three, and the t4 and t5 loci each bearing two alleles.