Osmotins form pores in fungal membranes that lead to osmotic rupture and destruction of the fungal cells. A study of the chromosomal arrangement, gene organization, and regulation of expression of cotton genes for the antifungal protein characterized two cotton genes and a cDNA clone for osmotin. Physical mapping determined that the cotton genomic insert in the lambda clone LCgOSM 16B was 16 kb. the segment enocompassed a full length gene with an open reading frame of 729 base pairs without any introns and encoded a presumptive osmotin-like preprotein of 242 amino acids. Another gene was almost full length, but lacked the 5' flanking promoter region and eight codons of the N-terminal coding region. The putative preprotein from this gene featured an N-terminal signal sequence, but lacked a C-terminal propeptide for vacuolar targeting. In addition to basal TATA and CAAT promoter elements, other prospective promoter/enhancer elements occurred in the 5' flanking sequence of the full length gene. 32 refs.