Isolation and characterization of a sterile-dwarf mutant in Asian cotton (Gossypium arboreum L.).

Plant height is an important trait in cotton. To elucidate the molecular mechanisms of the dwarf phenotype, a sterile-dwarf mutant derived from Gossypium arboreum L. cv. Jinhuazhongmian was developed by (60)Co gamma-ray irradiation. The results demonstrated that the sterile dwarf mutant phenotype was controlled by a pair of recessive gene, which was designated sd(a). Plants carrying the sd(a) gene contained lower levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) compared with wild-type (WT) plants. The chlorophyll content and net photosynthetic rate in mutant leaves were markedly decreased. However, it was possible that ABA biosynthesis or signaling was involved in governing the sd(a) phenotype. Semi-quantitative RT-PCR analysis detected 13 differentially expressed ESTs, and the sterile-dwarf mutant exhibited decreased expression levels relative to the WT. The role of nine potential hormone biosynthetic genes in the synthesis of IAA, ABA, polyamines (PAs) and jasmonic acid (JA) were discussed.