Two New Alleles at the sm 1 Locus in Cotton 1

Two new alleles were sited at the sm 1 locus of tetraploid Gossypium hirsutum L., upland cotton. One allele, derived from the wild Hawaiian tetraploid species, G.tomentosum Nutt. ex Seem., removed all trichomes from stems and most of the trichomes from mature leaves. The allele is dominant to “normally pubescent”, the phenotype of most cultivars of upland cotton. The second allele steins from the Peruvian diploid species, G. raimondii Ulbr. The allele greatly enhanced density of tomentum of the upland cultivar ‘Empire,’ is dominant to “normally pubescent,” and masks the expression of Sm 2 (A subgenome glabrousness allele). The finding of an allele at the sm 1 locus that enhances the density of pubescence, taken along with three other alleles at the locus that remove varying amounts of pubescence from the cotton plant, suggests that the sm 1 , locus of the D subgenome is the homoeologue of the sm 2 , or h 1 , locus of the A subgenome which bears an assortment of alleles that produce similar effects.