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Endophytic colonization and biocontrol performance of P seudomonas fluorescens PICF 7 in olive ( O lea europaea L.) are determined neither by pyoverdine production nor swimming motility
Author(s) -
MaldonadoGonzález M. Mercedes,
Schilirò Elisabetta,
Prieto Pilar,
MercadoBlanco Jesús
Publication year - 2015
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12725
Subject(s) - biology , colonization , mutant , siderophore , microbiology and biotechnology , verticillium dahliae , endophyte , botany , bacteria , gene , genetics
Summary P seudomonas fluorescens PICF 7 is an indigenous inhabitant of olive ( O lea europaea L.) rhizosphere, able to display endophytic lifestyle in roots, to induce a wide range of defence responses upon colonization of this organ and to exert effective biological control against Verticillium wilt of olive ( VWO ) ( V erticillium dahliae ). We aimed to evaluate the involvement of specific PICF 7 phenotypes in olive root colonization and VWO biocontrol effectiveness by generating mutants impaired in swimming motility ( fliI ) or siderophore pyoverdine production ( pvdI ). Besides, the performance of mutants with diminished in vitro growth in potato dextrose agar medium ( gltA ) and cysteine ( Cys ) auxotrophy was also assessed. Results showed that olive root colonization and VWO biocontrol ability of the fliI , pvdI and gltA mutants did not significantly differ from that displayed by the parental strain PICF 7. Consequently, altered in vitro growth, swimming motility and pyoverdine production contribute neither to PICF 7 VWO suppressive effect nor to its colonization ability. In contrast, the Cys auxotroph mutant showed reduced olive root colonization capacity and lost full biocontrol efficacy. Moreover, confocal laser scanning microscopy revealed that all mutants tested were able to endophytically colonize root tissue to the same extent as wild‐type PICF 7, discarding these traits as relevant for its endophytic lifestyle.