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A novel gene cluster involved in high tolerance to copper compounds has been detected in Pseudomonas syringae pv. syringae

Gutiérrez Barranquero, José Antonio,Aprile, Francesca,Cazorla-López, Francisco Manuel,De-Vicente-Moreno, Antonio

Abstract

Pseudomonas syringae pv. syringae (Pss), is the most polyphagous bacterium of the P. syringae complex, based on its wide host range, that severely affects woody and herbaceous plants. Pss has been described as the causal agent of bacterial apical necrosis (BAN) on mango crops, an important threat that drastically reduces the mango fruit yield in the Mediterranean region. Copper compounds have traditionally been used as standard bactericides to manage woody plant diseases, being the spraying of copper compound known as Bordeaux mixture (BM), the conventional treatment for controlling BAN disease. The extensive use of copper compounds can lead to many problems, and among them, the emergence of copper-resistant strains is one of the most serious. Pss strains isolated from mango trees harbour at least, two different genetic structures (copABCD and copABCD modified) encoded by plasmids that are involved in copper detoxification. Determination of the minimum inhibitory concentration of copper, together with a phylogenetic distribution analysis performed in a collection of Pss strains isolated from mango trees revealed a phylogenetic group of Pss strongly associated with high levels of copper resistance. Genome mining and functional characterization of one Pss strain present in this group have uncovered a novel gene cluster of chromosomal location that could be playing a major role in high levels of copper resistance during the epiphytic survival of Pss on mango tree surfaces.

Full text

A no el gene clus e in ol ed in high ole ance o coppe compounds has been de ec ed in Pseudomonas sy ingae p . sy ingae José A. Gu ié ez-Ba anque o, F ancesca Ap ile, F ancisco Cazo la and An onio de Vicen e. Ins i u o de Ho o u icul u a Sub opical y Medi e ánea “La Mayo a” (IHSM-UMA-CSIC), Depa amen o de Mic obiología, Facul ad de Ciencias, Uni e sidad de Málaga, Spain. Pseudomonas sy ingae p . sy ingae (Pss), is he mos polyphagous bac e ium o he P. sy ingae complex, based on i s wide hos ange, ha se e ely a ec s woody and he baceous plan s. Pss has been desc ibed as he causal agen o bac e ial apical nec osis (BAN) on mango c ops, an impo an h ea ha d as ically educes he mango ui yield in he Medi e anean egion. Coppe compounds ha e adi ionally been used as s anda d bac e icides o manage woody plan diseases, being he sp aying o coppe compound known as Bo deaux mix u e (BM), he con en ional ea men o con olling BAN disease. The ex ensi e use o coppe compounds can lead o many p oblems, and among hem, he eme gence o coppe - esis an s ains is one o he mos se ious. Pss s ains isola ed om mango ees ha bou a leas , wo di e en gene ic s uc u es (copABCD and copABCD modi ied) encoded by plasmids ha a e in ol ed in coppe de oxi ica ion. De e mina ion o he minimum inhibi o y concen a ion o coppe , oge he wi h a phylogene ic dis ibu ion analysis pe o med in a collec ion o Pss s ains isola ed om mango ees e ealed a phylogene ic g oup o Pss s ongly associa ed wi h high le els o coppe esis ance. Genome mining and unc ional cha ac e iza ion o one Pss s ain p esen in his g oup ha e unco e ed a no el gene clus e o ch omosomal loca ion ha could be playing a majo ole in high le els o coppe esis ance du ing he epiphy ic su i al o Pss on mango ee su aces.