Sap Microbiome of Southern California

Grapevine is a pillar of the California state economy and agricultural identity. The grapevine vascular system plays a key role by transporting nutrient, water, and signals throughout the plant. We hypothesized that grapevine host in its sap, microbes thathave a beneficial impact on plant health by protecting against pathogen attack and supporting key biological processes. The negative pressure, low oxygen and nutrient content of the xylem sap make it a unique and unexplored microbial environment. Toaddress this hypothesis, we chose a vineyard under high Pierce’s disease (PD). PD is caused by the xylem-dwelling pathogenic bacterium Xylella fastidiosa. We selected ten grapevines within this vineyard with different PD severity ratings and monitoredthem over 2 growing seasons. We sampled the vine’s sap at key phenological stages (bloom, veraison, and post-harvest) and usedan amplicon metagenomics approach to profile the bacterial (16s -V4) and fungal (ITS) communities of the sap.