iTRAQ-based quantitative proteomic analysis of cotton (Gossypium hirsutum L.) leaves reveals pathways associated throughout the aging process

Leaf senescence is associated with changes in proteomics. In this study, to quantitatively analyze changes in protein abundance related to leaf senescence in cotton (Gossypium hirsutum L.), we employed a proteomic approach utilizing iTRAQ and physiological assays throughout the senescence of leaf tissue in cotton grown under typical field conditions. Physiological tests showed leaf chlorophyll content and photosynthetic rates decreased significantly throughout the aging process. A total of 195 differentially abundant proteins (DAPs) throughout leaf senescence were identified by mass spectrometry. Of these, 91 (47%) proteins were upregulated, while the remaining 104 (53%) were downregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses indicated that the expression of genes in several pathways potentially associated with aging changed throughout senescence, including metabolic pathways, photosynthesis, pyruvate metabolism, nitrogen metabolism, and diterpenoid biosynthesis. Our findings provide a deeper understanding of aging in plants as well as fundamental data describing leaf senescence in cotton.