Genomic analysis of two Pseudomonas spp. strains displaying endophytic lifestyle in olive roots and effective biological control of Verticillium dahliae

Abstract

Pseudomonas jluorescens PICF7 and Pseudomonas pulida PICP2 are two effective biocontrol strains against Verticillium wilt (Verticillium dahliae Kleb.) of olive. In addition, both bacteria can colonize endophytically olive roots, even simultaneously. However, our knowledge on bacteria! traits involved in biological control and endophytic lifestyle is scarce. In this study, we have sequenced and annotated the complete genomes of strains PICF7 (1 contig, 6.14 Mbp) and PICP2 (63 contigs, 5.60 Mbp). A comparative bioinformatics analysis was catTied out aiming to identify genes potentially involved in (i) biological control, (ii) plant-bacteria interaction, and (iii) endophytism. The analysis has revealed that, among other determinants frequently associated to biocontrol andlor plant-bacteria interaction, the genome of strain PICF7 harbours the genetic information to encode two type VI (T6SS) and one Type III (T3SS) secretion systems, the T3SS effectors avrE 1 and hopB 1, the siderophores pyoverdine, pyochelin and the hemophore HasAp, diverse adhesion factors, a battery of celldegrading enzymes (protease, cellulase and lipase), as well as detoxifying systems such as CopA, KatB, Dps and Cbb. On the contrary, the genome of strain PICP2 showed, among other differences, no coding region for T3SS. Sorne ofthe phenotypes predicted by genome analysis have been demonstrated by biochemical and microbiological analyses. The availability of both genomes will help to understand both biocontrol activity and the ability to colonize and persist within olive root tissues.