Comparative proteomic analysis reveals the mechanisms governing cotton fiber differentiation and initiation

Cotton fibers are single-celled seed trichomes and provide an ideal model for studying plant cell patterning. At present, the molecular mechanisms of fiber differentiation and initiation are unclear. To determine the proteins involved in these processes, a comparative proteomic analysis based on 2-DE and MS/MS technology was conducted between the fuzzless-lintless mutant (fl) and its parental wild type (WT). Forty-six differentially expressed proteins were identified in ovules at -3 and 0 days post-anthesis (DPA), at the times of cotton fiber differentiation and initiation, respectively. Most of the proteins (72%) were expressed at lower levels in the fl mutant than in the WT, suggesting deleterious effects of the mutant genes on ovule development. The consistency between protein levels and transcript levels was examined using quantitative PCR. The differentially expressed proteins had diverse putative functions related to redox homeostasis, stress responses, post-transcriptional and post-translational regulation, and carbohydrate, energy, protein, amino acid, and sterol metabolism. A strong burst of ROS was detected on the surface of -3 and -2 DPA fl ovules, and the concentrations of several carbohydrates at 0 DPA were lower in the fl mutant than in the WT ovules. These findings suggest that ROS homeostasis may be a central regulatory mechanism for cotton fiber morphogenesis and that post-transcriptional and post-translational regulation may be pivotal in this process.