Unravelling cadmium toxicity and nitric oxide induced tolerance in Cucumis sativus: Insight into regulatory mechanisms using proteomics

Nitric oxide (NO) is a signal molecule that can mediate a wide range of physiological processes against cadmium (Cd) toxicity in plants. However, little information can be used to reveal the global and systematic mitigative mechanism of NO in improving Cd stress tolerance of cucumber plants. In the present study, we used Isobaric Tag for Relative and Absolute Quantification (iTRAQ) analysis to identify 1691 proteins, which can be used to determine the role of NO in regulating the molecular changes of proteome in cucumber leaves exposed to Cd stress. Several dysregulated key proteins indicated that Cd-induced physiological deterioration of cucumber leaves were mainly involved in metabolic process, cellular process, response to stimulus and so on. Metabolic pathway analysis indicated that several Cd-disruptive pathways were markedly reversed by NO treatments, including Cd transport and localization, photosynthesis, chlorophyll metabolism, redox homeostasis, glutathione-mediated Cd detoxification and Ca2+ signaling transduction. Taken together, this iTRAQ analysis provides more comprehensive insights into the physiological and molecular mechanisms of NO against Cd toxicity in cucumber plants.