Elucidation of Cross-Talk and Specificity of Early Response Mechanisms to Salt and PEG-Simulated Drought Stresses in Brassica napus Using Comparative Proteomic Analysis

Abstract

To understand the cross-talk and specificity of the early responses of plants to salt and drought, we performed physiological and proteome analyses of Brassica napus seedlings pretreated with 245 mM NaCl or 25% polyethylene glycol (PEG) 6000 under identical osmotic pressure (-1.0 MPa). Significant decreases in water content and photosynthetic rate and excessive accumulation of compatible osmolytes and oxidative damage were observed in response to both stresses. Unexpectedly, the drought response was more severe than the salt response. We further identified 45 common differentially expressed proteins (DEPs), 143 salt-specific DEPs and 160 drought-specific DEPs by isobaric tags for relative and absolute quantitation (iTRAQ) analysis. The proteome quantitative data were then confirmed by multiple reaction monitoring (MRM). The differences in the proteomic profiles between drought-treated and salt-treated seedlings exceeded the similarities in the early stress responses. Signal perception and transduction, transport and membrane trafficking, and photosynthesis-related proteins were enriched as part of the molecular cross-talk and specificity mechanism in the early responses to the two abiotic stresses. The Ca2+ signaling, G protein-related signaling, 14-3-3 signaling pathway and phosphorylation cascades were the common signal transduction pathways shared by both salt and drought stress responses; however, the proteins with executive functions varied. These results indicate functional specialization of family proteins in response to different stresses, i.e., CDPK21, TPR, and CTR1 specific to phosphorylation cascades under early salt stress, whereas STN7 and BSL were specific to phosphorylation cascades under early drought stress. Only the calcium-binding EF-hand family protein and ZKT were clearly identified as signaling proteins that acted as cross-talk nodes for salt and drought signaling pathways. Our study provides new clues and insights for developing strategies to improve the tolerance of crops to complex, multiple environmental stresses.

Study of the Interactive Effects of Calcium and Abscisic Acid on Drought Stressed Triticum aestivum Seedlings

“…In accordance with these findings, it was reported that drought stress led to a decrease in the Fv/Fm ratio in bean plant, STUDY OF THE INTERACTIVE EFFECTS OF CALCIUM ... suggesting chronic photo-inhibition due to photooxidation of photosynthetic apparatus (Sewelam et al, 2014) and damage to the PSII oxygenevolving complex possibly attributable to D1 protein damage under drought stress (Zlatve & Yordanov, 2004). Likewise, it was suggested that the photosynthetic efficiency has been declined in Nothofagus species under drought stress (Piper et al, 2007 andLuo et al, 2015). Similar effects on chlorophyll fluorescence parameters under drought stress have been observed in different species, among them Brassica napus (Kauser et al, 2006) and Aegilops species (Dulai et al, 2006).…”

“…+ and ABA alleviate these effects Drought as well as almost all abiotic stresses induce the accumulation of ROS leading to an oxidative cell damage (Luo et al, 2015), especially the oxidation of lipids in cell membranes. Results of the present study showed a highly significant increase in lipid peroxidation levels (measured as MDA content) under PEG treatment (Fig.…”

Selection and Breeding of Suitable Crop Genotypes for Drought and Heat Periods in a Changing Climate: Which Morphological and Physiological Properties Should Be Considered?

“…Deeper proteome coverage especially for less abundant proteins (signaling, transporters, etc.) is reached by the second generation shotgun proteomics [153][154][155]. Knowledge about dynamic changes of crop proteomes in response to abiotic stresses is regularly reviewed [131,150,152,153,156].…”

“…Recent proteomic studies on drought response of crops encompass different plant species, such as wheat [138,157], rice [158,159], barley [160], brassica [154], legumes [141,161]. Different types of tissues are studied: roots [141,154,159], root nodules [161], leaves [138,160], roots and leaves compared at seedling stage [157], roots, flag leaves and spikelets at reproductive stage [151].…”

“…Different types of tissues are studied: roots [141,154,159], root nodules [161], leaves [138,160], roots and leaves compared at seedling stage [157], roots, flag leaves and spikelets at reproductive stage [151]. As the high temperature is particularly detrimental during the reproductive stage, besides the studies on leaf proteome under heat stress in rice [113,162], wheat [163] radish [142], alfalfa [164] and stromal proteins in agave [165], special attention is paid to the reproductive phase [166], source-sink interactions at grain filling [167], grain development and composition [155,160] in cereals, and protein composition of soybean seeds [168] formed under unfavorable temperature conditions.…”