Aj. Reinisch et al., A DETAILED RFLP MAP OF COTTON, GOSSYPIUM-HIRSUTUM X GOSSYPIUM BARBADENSE - CHROMOSOME ORGANIZATION AND EVOLUTION IN A DISOMIC POLYPLOID GENOME, Genetics, 138(3), 1994, pp. 829-847
We employ a detailed restriction fragment length polymorphism (RFLP) m
ap to investigate chromosome organization and evolution in cotton, a d
isomic polyploid. About 46.2% of nuclear DNA probes detect RFLPs disti
nguishing Gossypium hirsutum and Gossypium barbadense; and 705 RFLP lo
ci are assembled into 41 linkage groups and 4675 cM. The subgenomic or
igin (A vs. D) of most, and chromosomal identity of 14 (of 26), linkag
e groups is shown. The A and D subgenomes show similar recombinational
length, suggesting that repetitive DNA in the physically larger A sub
genome is recombinationally inert. RFLPs are somewhat more abundant in
the D subgenome. Linkage among duplicated RFLPs reveals 11 pairs of h
omoeologous chromosomal regions-two appear homosequential, most differ
by inversions, and at least one differs by a translocation. Most homo
eologies involve chromosomes from different subgenomes, putatively ref
lecting the n = 13 to n = 26 polyploidization event of 1.1-1.9 million
years ago. Several observations suggest that another, earlier, polypl
oidization event spawned n = 13 cottons, at least 25 million years ago
. The cotton genome contains about 400-kb DNA. per cM, hence map-based
gene cloning is feasible. The cotton map affords new opportunities to
study chromosome evolution, and to exploit Gossypium genetic resource
s for improvement of the world's leading natural fiber.