A revised map of chromosome 16 in Gossypium hirsutum
Four translocations involving chromosome 16 (H16) in cotton (T1R;16R 2770, T1R;16R 4672, T15L;16R 8-5Ga, and T15R;16R 2767) were tested against telosomes for chromosome 16 and the H16 marker gene red plant (R1). The telosome tests confirmed that bp-2770 and bp-4672 are in the long (=right) arm of chromosome 16 and showed that bp-8-5Ga and bp-2767 are also in the long arm of H16, rather than in the short (=left) arm as previously reported. The locations of the chromosome 15 (H15) bp's for 8-5Ga and 2767 are also revised. A telosome test showed that H15 bp-8-5Ga is in the long (=left) arm. Consequently, H15 bp-2767 is placed in the short (=right) arm of chromosome 15. Duplication deficiencies mono- or tri-segmental for H16 (verified cytologically) showed that R1 is in the right (R) arm 24 cM distal to bp-2767 and 10 cM distal to bp-8-5Ga. Recombination frequencies showed that R1 is 13 cM from bp-4672 and 15 cM from bp-2770 (not significantly different). However, both of the T1R;16R translocations yield negligible frequencies of duplication deficiencies and therefore offered no direct evidence as to whether their breakpoints are proximal or distal to R1. Previous estimates have placed both bp-2770 and bp-4672 43 cM from the centromere. Therefore the order must be as follows: (left)–centromere–bp-2767-bp-8-5Ga–R1–bp-4672/bp-2770 (right). Key words: cotton, Gossypium hirsutum, chromosome 16, translocations, linkage map, duplication-deficiences, red plant, linkage group III.