Pierce’s Disease (PD) is a devastating bacterial disease plaguing California vineyards. PD is caused by Xylella fastidiosa (Xf), which clogs the xylem of grapevines, preventing the flow of nutrients and water and leading to dwarfed plants with shriveled fruits that are ultimately unusable for winemaking. Interestingly, it is common in PD-infected vineyards to observe infected vines living in close proximity to ‘disease-escaped’ vines (those that do not express symptoms of PD), despite being genetically identical. This suggests that a non-genetic factor might be providing resistance to PD. With the hypothesis that natural products produced by endophytic microorganisms might be responsible for this resistance, the microbial communities residing in infected vines were compared to those in disease-escaped vines in order to identify organisms conferring resistance to Xf. Several endophytic fungi and bacteria that strongly inhibit the growth of Xf were isolated and bioassay-guided isolation was performed to purify anti-Xf natural products. Using NMR spectroscopy and mass spectrometry, structures of two known natural products from Cochliobolus sp. and Ulocladium sp. were elucidated. These natural products, radicinin and alteichin, inhibit Xf in vitro, and the exploration of their activity in planta is currently underway.

Isolation and structure elucidation of alteichin, a fungal natural product that inhibits Xylella fastidiosa, the bacterium that causes Pierce's Disease

255th National Meeting (2018)

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