Differential proteomic analysis of grapevine leaves by iTRAQ reveals responses to heat stress and subsequent recovery

Abstract

Background: High temperature is a major environmental factor limiting grape yield and affecting berry quality. Thermotolerance includes the direct response to heat stress and the ability to recover from heat stress. To better understand the mechanism of the thermotolerance of Vitis, we combined a physiological analysis with iTRAQ-based proteomics of Vitis vinifera cv Cabernet Sauvignon, subjected to 43°C for 6 h, and then followed by recovery at 25/18°C.

Results: High temperature increased the concentrations of TBARS and inhibited electronic transport in photosynthesis apparatus, indicating that grape leaves were damaged by heat stress. However, these physiological changes rapidly returned to control levels during the subsequent recovery phase from heat stress. One hundred and seventy-four proteins were differentially expressed under heat stress and/or during the recovery phase, in comparison to unstressed controls, respectively. Stress and recovery conditions shared 42 proteins, while 113 and 103 proteins were respectively identified under heat stress and recovery conditions alone. Based on MapMan ontology, functional categories for these dysregulated proteins included mainly photosynthesis (about 20%), proteins (13%), and stress (8%). The subcellular localization using TargetP showed most proteins were located in the chloroplasts (34%), secretory pathways (8%) and mitochondrion (3%).

Conclusion: On the basis of these findings, we proposed that some proteins related to electron transport chain of photosynthesis, antioxidant enzymes, HSPs and other stress response proteins, and glycolysis may play key roles in enhancing grapevine adaptation to and recovery capacity from heat stress. These results provide a better understanding of the proteins involved in, and mechanisms of thermotolerance in grapevines.

Figure 1

TBARS in grape leaves under heat stress and subsequent recovery. It is showed that heat treatment (43°C for 6 h) significantly increased the TBARS concentrations in grape leaves and after subsequent recovery, there was no difference in TBARS concentrations between heat-treated and control leaves. Each value represents the mean ± standard error of the mean (S.E.M.) of three replicates. The asterisks indicate the significance of differences between treatments and their corresponding controls (* P < 0.05).

Figure 2

Donor side (W_k), reaction center (RC_QA), acceptor side (φ_Po, ψ_Eo, φ_Eo) parameters of PSII and δ_Ro (the efficiency with an electron can move from plastoquinone (PQ) through PSI to the PSI end electron acceptor) in grape leaves under heat stress and subsequent recovery. Each value represents the mean ± S.E. of five replicates. The asterisks indicate the significance of differences from their corresponding control (* P < 0.05, ** P < 0.01). The detailed meanings of W_k, RC_QA, φ_Po, ψ_Eo, φ_Eo and δ_Ro were shown in Additional file 7.

Figure 3

Venn diagram of differentially expressed proteins that were up- or downregulated by heat stress or recovery. The “ + “ and “- “indicate up- and downregulated proteins, respectively.

Figure 4

Functional characterization of heat stress and recovery–responsive proteins under heat stress and/or subsequent recovery.

Figure 5

Subcellular localization of the 174 differentially expressed proteins under heat stress and/or subsequent recovery. C: Chloroplast, i.e. the sequence contains cTP, a chloroplast transit peptide; M: Mitochondrion, i.e. the sequence contains mTP, a mitochondrial targeting peptide; S: Secretory pathway, i.e. the sequence contains SP, a signal peptide; _: Any other location; *: “don't know”.

Figure 6

MapMan visualization of photosynthesis in grapevine leaves under heat stress (A) and subsequent recovery (B).

Figure 7

Overview of cellular response in grapevine leaves under heat stress (A) and subsequent recovery (B) visualized by MapMan.