Comparative leaf proteomics of drought-tolerant and -susceptible peanut in response to water stress

Abstract

Water stress (WS) predisposes peanut plants to fungal infection resulting in pre-harvest aflatoxin contamination. Major changes during water stress including oxidative stress, lead to destruction of photosynthetic apparatus and other macromolecules within cells. Two peanut cultivars with diverse drought tolerance characteristics were subjected to WS, and their leaf proteome was compared using two-dimensional electrophoresis complemented with MALDI-TOF/TOF mass spectrometry. Ninety-six protein spots were differentially abundant to water stress in both cultivars that corresponded to 60 non-redundant proteins. Protein interaction prediction analysis suggests that 42 unique proteins showed interactions in tolerant cultivar while 20 showed interactions in the susceptible cultivar, activating other proteins in directed system response networks. Four proteins: glutamine ammonia ligase, chitin class II, actin isoform B, and beta tubulin, involved in metabolism, defense and cellular biogenesis, are unique in tolerant cultivar and showed positive interactions with other proteins. In addition, four proteins: serine/threonine protein phosphate PP1, choline monooxygenase, peroxidase 43, and SNF1-related protein kinase regulatory subunit beta-2, that play a role as cryoprotectants through signal transduction, were induced in drought tolerant cultivar following WS. Eleven interologs of these proteins were found in Arabidopsis interacting with several proteins and it is believed that similar mechanisms/pathways exist in peanut.

Significance: Peanuts (Arachis hypogaea L.) are a major source of plant protein grown in subtropical and tropical regions of the world. Pre-harvest aflatoxin contamination is a major problem that affects peanut crop yield and food safety. Poor understanding of molecular and cellular mechanisms associated with aflatoxin resistance is largely responsible for the lack of progress in elucidating a process/methodology for reducing aflatoxin contamination in peanuts. Drought perturbs the invasion of the aflatoxin producing fungus and thus affects the quality and yield of peanut. Therefore, more studies involving the effects of drought stress to determine the molecular changes will enhance our understanding of the key metabolic pathways involved in the combined stresses. The changes associated with the biotic and abiotic interactions within the peanut will be used to determine the metabolic pathways involved in the stress tolerance. This research would be beneficial in identifying the tolerant molecular signatures and promoting food safety and consumer health through breeding superior quality peanut cultivars.

Keywords: Drought tolerance; Leaf proteins; Protein-protein interaction; Two-dimensional electrophoresis; Water stress.