Comparative genomics to examine the endophytic potential of Pantoea agglomerans DAPP-PG 734

Pantoea agglomerans DAPP-PG 734 was isolated as endophyte from knots (tumors) caused by Pseudomonas savastanoi pv. savastanoi DAPP-PG 722 in olive trees. To understand the plant pathogen-endophyte interaction on a genomic level, the whole genome of P. agglomerans DAPP-PG 734 was sequenced and annotated. The complete genome had a total size of 5'396'424 bp, containing one circular chromosome and four large circular plasmids. The aim of this study was to identify genomic features that could play a potential role in the interaction between P. agglomerans DAPP-PG 734 and P. savastanoi pv. savastanoi DAPP-PG 722. For this purpose, a comparative genomic analysis between the genome of P. agglomerans DAPP-PG 734 and those of related Pantoea spp. was carried out. In P. agglomerans DAPP-PG 734, gene clusters for the synthesis of the Hrp-1 type III secretion system (T3SS), type VI secretion systems (T6SS) and autoinducer, which could play an important role in a plant-pathogenic community enhancing knot formation in olive trees, were identified. Additional gene clusters for the biosynthesis of two different antibiotics, namely dapdiamide E and antibiotic B025670, which were found in regions between integrative conjugative elements (ICE), were observed. The in-depth analysis of the whole genome suggested a characterization of the P. agglomerans DAPP-PG 734 isolate as endophytic bacterium with biocontrol activity rather than as a plant pathogen.