Core and Keystone Epiphytic and Endophytic Bacteria Associated With Potato Leaves Are Driven by Cultivar and Site.

Bacteria that colonise leaf surfaces and internal tissues benefit potato health and productivity. Whether these bacteria are present across potato cultivars and production fields is unknown. Leaf samples were collected from field-grown potatoes (Imperial Blue, Innovator, Nicola, and Royal Blue) at 12 commercial farms across three production regions in Australia. Epiphytic and endophytic bacteria were analysed by amplicon sequencing. Both cultivar and site influenced the bacterial community composition, with endophytes strongly influenced by cultivar, while epiphytes were less consistent. Site-specific bacteria varied with climate, with limited influence from location. Endophytic bacteria identified across cultivars and sites were a Delftia sp., Acinetobacter sp., and Caldalkalibacillus thermarum. The same Delftia sp. and C. thermarum were also cultivar-specific core endophytes in cvs. Imperial Blue, Innovator, and Royal Blue. A Pantoea sp. was the only core epiphyte. The relative abundance of reproducible core taxa was not significantly different between cultivars. The Delftia sp. was the only putative keystone taxon in both endophyte and epiphyte communities in multiple cultivars. The results suggest that potato leaf bacterial communities are influenced by cultivar and site, but also have a shared core. These findings support isolation and further investigation of the roles of core bacterial taxa in potatoes.