The Tolerance of Gossypium hirsutum for Deficiencies and Duplications

Exposure of germinating seeds of G. hirsutum to 1200r of X-rays was effective in producing chromosome aberrations. Ten lines having 12 different translocation complexes were recovered, involving a minimum of 29 breaks and rearrangements. At least ten, and probably all twelve, of these complexes gave one or more viable and fertile deficiency-duplication genotypes when outcrossed. Several of the complexes differed in the size of the chromosomes and length of the interchanged arms in such a way as to permit identification of the heterozygote and some or all of the deficiency-duplications by the configurations formed at metaphase I. In three lines, deficiency-duplications for segments carrying marker genes were recovered. It is concluded that the recovery of viable, fertile deficiency-duplications from translocations is the rule rather than the exception in this amphidiploid species.