iTRAQ-based quantitative proteomic of tobacco (Nicotiana tabacum L.) identified major host proteins involved in photosystems throughout the aging process

Abstract Background Leaf senescence is one of the most common manifestations in plant senescence and has an important effect on photosynthesis. However, the molecular regulation of leaf senescence in response to photosynthesis is still poorly understood. To gain insight into the molecular mechanisms underpinning tobacco, we integrated photosynthesis, organelle ultrastructural, and proteomic analyses of tobacco leaves during senescence.Results The photosynthetic rate, intercellular CO 2 concentration, tomatal conductance, transpiration rate showed a downward trend and the stability of organelle decreased with the increasing of tobacco leaves age. iTRAQ and PRM verification were used to analyze the proteins expressed in different periods based on photosynthetic physiology and ultramicroscopic observation. A total of 321, 319, 223 differentially expressed proteins (DEPs) were identified from over maturity (OM) vs immature (IM), OM vs well maturity (WM) and WM vs IM, respectively, including 122/199, 124/195 and 125/98 up/down proteins, respectively. KEGG analysis of DEPs was significantly enriched in metabolic pathways, biosynthesis of secondary metabolites, microbial metabolism in diverse environments, starch and sucrose metabolism. In addition, down-regulated proteins were also involved in metabolic pathways such as carbon sequestration of photosynthetic organisms and photosynthesis. Furthermore, PRM analysis indicated that iTRAQ is highly reliable.Conclusions Our study provided important technical references for screening photosynthetic host proteins of tobacco leaf senescence and revealing the molecular mechanism during the senescence of tobacco leaves.