Find in Library

Ethylene plays a pivotal role in plant stress resistance and 1-aminocyclopropane-1-carboxylic acid synthase (ACS) is the rate-limiting enzyme in ethylene biosynthesis. Upland cotton (<i>Gossypium hirsutum</i> L.) is the most important natural fiber crop, but the function of ACS in response to abiotic stress has rarely been reported in this plant. We identified 18 <i>GaACS</i>, 18 <i>GrACS</i>, and 35 <i>GhACS</i> genes in <i>Gossypium</i><i>arboreum</i>, <i>Gossypium</i> <i>raimondii</i> and <i>Gossypium</i><i>hirsutum</i>, respectively, that were classified as types I, II, III, or IV. Collinearity analysis showed that the <i>GhACS</i> genes were expanded from diploid cotton by the whole-genome-duplication. Multiple alignments showed that the C-terminals of the GhACS proteins were conserved, whereas the N-terminals of GhACS10 and GhACS12 were different from the N-terminals of AtACS10 and AtACS12, probably diverging during evolution. Most type II <i>ACS</i> genes were hardly expressed, whereas <i>GhACS10</i>/<i>GhACS12</i> were expressed in many tissues and in response to abiotic stress; for example, they were highly and hardly expressed at the early stages of cold and heat exposure, respectively. The <i>GhACS</i> genes showed different expression profiles in response to cold, heat, drought, and salt stress by quantitative PCR analysis, which indicate the potential roles of them when encountering the various adverse conditions, and provide insights into GhACS functions in cotton’s adaptation to abiotic stress.