نبذة مختصرة : Drought is a major abiotic stress factor that affects the yield of maize (Zea mays L.) during the grain filling period. Therefore, it is critical to reveal the molecular mechanisms underlying maize drought stress tolerance. To analyze the characteristics and functions of differentially abundant proteins (DAPs) in response to drought stress during the maize kernel-filling stage, here, two maize hybrid varieties with contrasting drought tolerance (tolerant ND476 and sensitive ZX978) were subjected to water sufficient (control) and water deficit (drought) treatment conditions for 12 days at the grain filling stage. Physiological assays and leaf proteome analysis were performed. We conducted iTRAQ analysis on 12 samples from 4 groups and obtained 1,655 DAPs. Amongst these, five essential sets of drought responsive DAPs were identified by bioinformatics techniques. Four significantly enriched metabolic pathways were identified in ND476, which were shown to be associated with the ribosome, metabolic, basal transcription factors and photosynthesis pathways. Further, the phenotypic characterization and qRT-PCR analysis confirmed our iTRAQ sequencing data. Remarkably, significantly higher drought tolerance of ND476 may be attributed to the following responses: (a) oxidoreductase, peroxidase and hydrolytic enzyme activities to promote cell redox homeostasis maintenance; (b) elevated expression of stress defense proteins; and (c) reduced synthesis of redundant proteins in order to help plants preserve energy to fight drought stress. In conclusion, these results offer more insights into the molecular mechanisms underlying maize drought tolerance at the grain filling stage and can be a foundational basis for molecular breeding of drought tolerant maize varieties.
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