ITRAQ-based proteomic analysis reveals positive impacts of arbuscular mycorrhizal fungi inoculation on photosynthesis and drought tolerance in blueberry

Abstract

Our results from iTRAQ-based proteomics extend the understanding of the mechanisms employed by AMF to defend against drought stress in blueberry. Arbuscular mycorrhizal fungi (AMF) can substantially contribute to plant drought tolerance. In this work, south highbush blueberry (Vaccinium corymbosum) ‘O’Neal’ cultivated with or without Funneliformis mosseae inoculation under well-watered or drought-stressed conditions were evaluated through an isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics approach. In total, 3078 proteins and 501 differentially abundant proteins (DAPs) were identified, including 127, 30, 236, and 108 DAPs in drought-stressed plants vs well-watered, drought-stressed plants with AMF inoculation vs well-watered plants with AMF inoculation, AMF-inoculated well-watered plants vs non-inoculated well-watered plants, and AMF-inoculated plants under drought stress vs non-inoculated plants under drought stress paired comparisons, respectively. Relative to non-inoculated plants, AMF-inoculated plants under drought stress maintained a greater abundance of DAPs involved in amino acid metabolism, antioxidant system, signal transduction, and photosynthesis including carbon fixation in photosynthetic organisms, porphyrin and chlorophyll metabolism, and carotenoid biosynthesis. Physiological analyses revealed that AMF-inoculated plants exhibited a greater photosynthetic capacity than non-inoculated plants under drought stress, mainly through non-stomatal factors such as enhancements of the efficiency of excitation energy capture by chloroplasts and the photochemical capacity of photosystems. Thus, the findings could explain the AMF-induced physiological effects associated with drought tolerance. Studies on the proteomic responses specific to AMF in drought-stressed plants will help to clarify how mycorrhization elicits improved plant growth and stress tolerance responses.