Quercus species infected with Drippy Blight Metagenomic assembly. Quercus species infected with Drippy Blight

Drippy blight, an emergent bacterial disease of oaks, was described recently from urban oaks in the Front Range of Colorado, USA. This disease, characterized by significant branch dieback and oozing of bacterial exudates from branch cankers, is caused by Lonsdalea quercina and primarily affects red oaks, and Northern red oak (Quercus rubra) is most susceptible. A similar, less acute, condition, drippy nut, exists in California, USA and affects acorns of interior live oak (Quercus wislizenii) and coastal live oak (Quercus agrifolia). This study aims to determine if there are other pathogenic fungal or bacterial associates of the diseases and to compare the microbial communities of drippy blight in Colorado to those of drippy nut in California. Symptomatic and asymptomatic tissues were sampled in California and Colorado, and metagenomic analysis was performed to describe the fungal and bacterial communities. We found a suite of bacterial species, dominated by Zymobacters, that were associated with symptomatic tissues for both drippy nut and drippy blight. L. quercina is the main pathogenic associate of both diseases; however, the bacterial strain in Colorado differs genetically from the one in California. We primarily found a collection of fungal yeasts associated with symptomatic tissues, though not pathogens, they may present of the pathobiome of drippy nut and drippy blight in California and Colorado. Our study found an overlapping suite of bacterial associates of drippy blight and drippy nut, though few consistent fungal genera associated with these oak diseases.