[Gene mapping of an ultra-dwarf mutant in upland cotton]

A ultra-dwarf mutant was newly found in upland cotton (Gossypium hirsutum L.). This mutant was controlled by single recessive gene du. Seventy pairs of polymorphic primers were selected from 1350 primers, which covered all the identified chromosomes by screening in parents and near-isogenic lines. Gene du was mapped using an F2 population derived from intraspecific crosses between "Ultra-dwarf 1" and "Xinluzao 16". Thirty-six primers were distributed in eight linkage groups, and du was linked to LG01. Seven co-dominant markers linked to du were NAU2679, NAU2749, NAU905, NAU2838, NAU5373, NAU2238, and NAU4946. Based on the known genetic map of tetraploid cotton, the markers NAU4946, NAU2238, NAU905, NAU5373, and NAU2679 were located on chromosome 6, and the target gene du was located between NAU2238 and NAU4946 with the genetic distances of 3.3 cM and 1.4 cM, respectively. Hence, gene du was located on chromosome 6.