The Influence of the endosphere microbiome on Pierce’s disease development in grapevine.
M. ROPER (1), J. Yang (2), J. Borneman (1), P. Ruegger (1), P. Rolshausen (1) (1) University of California, Riverside, U.S.A.; (2) National Taiwan University, Taiwan

Xylella fastidiosa (Xf), is a xylem-limited bacterium that is the causal agent of Pierce’s disease (PD) of grapevine. PD is a major threat to the grape industry and has recently been implicated in a severe disease of olives in Italy reiterating its importance as a global, re-emerging pathogen. In vineyards that are heavily infected with PD, there are interesting examples of vines exhibiting either no symptoms or very mild PD symptoms (disease-escaped). All vines in a vineyard are clonal so the differences in tolerance to the disease are likely not attributed to the genetics of the plant. We hypothesize that the microorganisms inhabiting the xylem in these disease-escaped vines are inhibitory to Xf and subsequently reduce disease severity, due to their shared ecological niche. The goal of this project is to characterize the microbial communities residing in PD-infected vines and compare them to disease-escaped vines with the aim of identifying beneficial organisms that are antagonistic to Xf. We characterized the fungal and bacterial endophytic communities using an Illumina MiSeq platform targeting the ITS and 16S rRNA genes, respectively. Pseudomonadales was the most abundant bacterial taxonomic group and Pleosporales was the most abundant fungal taxonomic group. Most interestingly, some bacterial phylotypes that belong to the Pseudomodales, Burkholderiales, Rhodocyclales and Opitutales correlated negatively with PD severity. From this, we identified a subset of the endophytic microbes that were strongly inhibitory to Xf in vitro and also suppressed PD symptom development in greenhouse bioassays. We envision harnessing these microbes to construct a beneficial synthetic phytobiome that can be deployed into grapevines during the nursery propagation process.

Abstract Number: P4-116
Session Type: Poster