Proteomic profiling of Arachis hypogaea in response to drought stress and overexpression of AhLEA2 improves drought tolerance

Drought is the main factor restricting peanut growth, but the molecular mechanism underlying peanut drought tolerance remains unclear. Herein, the seedling stage of drought-resistant peanut cultivar J11 was subjected to drought stress, and its proteomic profile was systematically analysed by isobaric tags for relative and absolute quantification (iTRAQ), the results of which were further complemented with our previous transcriptome results. A total of 4,018 proteins were identified by proteomic analysis, which revealed that the expression levels of 69 proteins were altered under drought stress. Among the differentially expressed proteins (DEPs), 50 were upregulated, and 19 were downregulated. The most enriched metabolic pathways for these DEPs were those involving phenylpropanoid biosynthesis, flavonoid biosynthesis, and plant hormone signal transduction. The proteomic data and previous transcriptome results revealed 44 groups of genes/proteins with the same expression trend, including a LEA (Late embryogenesis abundant) gene, AhLEA2. Our present study showed that overexpression of the AhLEA2 gene enhanced the drought resistance of transgenic Arabidopsis plants, and the activities of related antioxidant enzymes in the transgenic plants significantly changed. The AhLEA2 gene was found to be located in the cytoplasm and cell membrane by subcellular localization experiments. This work systematically analysed the differentially expressed proteins in peanut in response to drought stress, providing important candidates for further functional analysis of the stress response of peanut. Our results also indicated that AhLEA2 plays an important role in the peanut response to drought stress.