A comparative analysis of a fuzzless-lintless mutant of Gossypium hirsutumL. cv. Xu-142

A fuzzless-lintless (fl) seed mutant of Gossypium hirsutum L. cv. Xu-142 wa s investigated to study cotton fiber development. Scanning electron microsc opy revealed that fiber initials were virtually absent from fl ovules. RT-P CR analysis showed that the steady-state levels of transcripts of the fiber -specific E6 and Expansin genes were high in wild type (WT) ovules during t he fiber initiation and elongation stages, and peaked around 15 days post a nthesis (DPA), but only a trace amount of these transcripts was detectable in fl ovules of all developmental stages investigated. CotmybA, a member of the Myb family, exhibited a clear expression in developing WT ovules, but the expression was abnormal in fl ovules. Application of GA(3), or GA(3) pl us IAA, to the culture medium rescued in vitro fiber initiation and growth of fl ovules only partially In addition, transcription of E6 and Expansin g enes of in vitro cultured WT and fl ovules responded similarly to exogenous hormones. The hormones had less effect on CotmybA transcription in ovules cultured in vitro, and again the WT and fl ovules showed a similar expressi on. These results suggest that the abnormal or extremely low level of expre ssion of E6, Expansin and CotmybA genes in developing fl seeds is related t o the absence of seed-hairs, and the mechanism underlying needs further inv estigation.