Multigenic resistance to Xylella fastidiosa in wild grapes (Vitis sps.) and its implications within a changing climate

Abstract

Xylella fastidiosa is a bacterium that infects crops like grapevines, coffee, almonds, citrus and olives, causing economically devastating damage. There is, however, little understanding of the genes that contribute to resistance, the genomic architecture of resistance, and the potential role of climate in shaping resistance, in part because major crops like grapevines (V. vinifera) are not resistant to the bacterium. Here we studied a wild grapevine species, Vitis arizonica, that segregates for resistance to X. fastidiosa. Using genome-wide association, we identified candidate genes that mediate the host response to X. fastidiosa infection. We uncovered evidence that resistance requires genes from multiple genomic regions, based on data from breeding populations and from additional Vitis species. We also inferred that resistance evolved more than once in the wild, suggesting that wild Vitis species may be a rich source for resistance alleles and mechanisms. Finally, resistance in V. arizonica was climate dependent, because individuals from low (< 10{degrees}C) temperature locations in the wettest quarter were typically susceptible to infection, likely reflecting a lack of pathogen pressure in these climates. Surprisingly, climate was nearly as effective a predictor of resistance phenotypes as some genetic markers. This work underscores that pathogen pressure is likely to increase with climate, but it also provides genetic insight and tools for breeding and transforming resistant crops.