Examination of mRNA abundance profiles comparing 5 leaf samples of diseased grapevines (5 trees) to 5 healthy (non-infected) grapevines.

Rationale: Pierce’s disease is a major threat to grapevines caused by the bacterium Xylella fastidiosa. Although devoid of a type 3 secretion system to deliver effectors inside host cells, this pathogen is able to influence host parenchymal cells from the xylem lumen by secreting a battery of hydrolytic enzymes. Defining the cellular and biochemical changes induced during disease can foster the development of novel therapeutic strategies.

Methods: To this end we investigated the transcriptional, proteomic and metabolomic responses of diseased Vitis vinifera compared to healthy plants.

Results: We found that several antioxidant strategies were induced, including the accumulation of GABA, arginine, proline and polyamine metabolism, as well as iron and copper chelation, but these were insufficient to protect the plant from chronic oxidative stress and resulting cell death. Notable upregulation of phytoalexins, pathogenesis-related proteins and various aromatic acid metabolites were part of the host responses observed. Moreover, upregulation of various cell wall modification enzymes followed the proliferation of the pathogen within xylem vessels, consistent with the intensive thickening of vessels’ secondary walls.

Conclusion: By interpreting the molecular profile changes taking place in symptomatic tissues, we report a group of molecular markers that may aid early disease detection, breeding for resistance, and developing therapeutics.

Accession number PRJNA390670