Proteomic analysis of early-stage incompatible and compatible interactions between grapevine and P. viticola

Guo-Tian Liu,David Lecourieux,Yan Xu,Rui-Qi Liu,Bo-Xing Shang,Mei-Jie Li,Fatma Lecourieux,Bian-Bian Wang,Li-Jun Wang,Xiao Yin,Ming-Bo Liu

doi:10.1038/s41438-021-00533-y

Abstract

Wild grapevines can show strong resistance to the downy mildew pathogen P. viticola, but the associated mechanisms are poorly described, especially at early stages of infection. Here, we performed comparative proteomic analyses of grapevine leaves from the resistant genotype V. davidii “LiuBa-8” (LB) and susceptible V. vinifera “Pinot Noir” (PN) 12 h after inoculation with P. viticola. By employing the iTRAQ technique, a total of 444 and 349 differentially expressed proteins (DEPs) were identified in LB and PN, respectively. The majority of these DEPs were related to photosynthesis, respiration, cell wall modification, protein metabolism, stress, and redox homeostasis. Compared with PN, LB showed fewer downregulated proteins associated with photosynthesis and more upregulated proteins associated with metabolism. At least a subset of PR proteins (PR10.2 and PR10.3) was upregulated upon inoculation in both genotypes, whereas HSP (HSP70.2 and HSP90.6) and cell wall-related XTH and BXL1 proteins were specifically upregulated in LB and PN, respectively. In the incompatible interaction, ROS signaling was evident by the accumulation of H2O2, and multiple APX and GST proteins were upregulated. These DEPs may play crucial roles in the grapevine response to downy mildew. Our results provide new insights into molecular events associated with downy mildew resistance in grapevine, which may be exploited to develop novel protection strategies against this disease.

Highlights

Grapevines (Vitis) include some of the most widely cultivated and most economically important fruit crops worldwide
Colonization in LB and Pinot Noir” (PN) at 12 hpi To evaluate the ability of P. viticola to colonize LB and PN, detached leaves from both genotypes were inoculated with cultures of P. viticola isolate “YL”, and observed for 12 h postinoculation by aniline blue staining and epifluorescence microscopy
These observations are consistent with previous reports showing that P. viticola can successfully infect and colonize both resistant and susceptible grapevine genotypes[5,27,28], and suggest that resistance to downy mildew in the LB-resistant genotype involves mechanisms, that are deployed after infection and colonization rather than constitutive physical and chemical barriers

Summary

Introduction

Grapevines (Vitis) include some of the most widely cultivated and most economically important fruit crops worldwide. Plasmopara viticola (Berk and Curt) Berl and de Toni, is a strictly obligate biotrophic pathogen that obtains nutrients from living cells of hosts to complete its life cycle through specialized structures called haustoria. It can infect leaves, shoots, tendrils, inflorescences, and young berries and spread into mature berries through rachis infection. Plants have evolved sophisticated surveillance systems to defend against pathogen attack[1,2] These may include preformed constitutive barriers such as a strong cell wall, a thickened waxy layer and dense trichomes on the epidermis, and the presence of antimicrobial toxins in the cell vacuole. During the ongoing evolutionary contest between host and pathogen, plants have developed resistance (R) genes encoding receptors that can

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