Implication of an Aldehyde Dehydrogenase Gene and a Phosphinothricin N-Acetyltransferase Gene in the Diversity of Pseudomonas cichorii Virulence.
Pseudomonas cichorii harbors the hrp genes. hrp-mutants lose their virulence on eggplant but not on lettuce. A phosphinothricin N-acetyltransferase gene (pat) is located between hrpL and an aldehyde dehydrogenase gene (aldH) in the genome of P. cichorii. Comparison of nucleotide sequences and composition of the genes among pseudomonads suggests a common ancestor of hrp and pat between P. cichorii strains and P. viridiflava strains harboring the single hrp pathogenicity island. In contrast, phylogenetic diversification of aldH corresponded to species diversification amongst pseudomonads. In this study, the involvement of aldH and pat in P. cichorii virulence was analyzed. An aldH-deleted mutant (ΔaldH) and a pat-deleted mutant (Δpat) lost their virulence on eggplant but not on lettuce. P. cichorii expressed both genes in eggplant leaves, independent of HrpL, the transcriptional activator for the hrp. Inoculation into Asteraceae species susceptible to P. cichorii showed that the involvement of hrp, pat and aldH in P. cichorii virulence is independent of each other and has no relationship with the phylogeny of Asteraceae species based on the nucleotide sequences of ndhF and rbcL. It is thus thought that not only the hrp genes but also pat and aldH are implicated in the diversity of P. cichorii virulence on susceptible host plant species.
Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan. tanakamasayukikani@yahoo.co.jp.
Masayuki
M
Tanaka
Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan. wullahsau@yahoo.com.
Ullah Md
UM
Wali
Laboratory of Plant Pathology, Kobe University, Kobe, Hyogo 657-8501, Japan. hnakaya@kobe-u.ac.jp.
Hitoshi
H
Nakayashiki
Faculty of Agriculture, Kochi University, Nankoku 783-8502, Japan. tfukuda@kochi-u.ac.jp.
Tatsuya
T
Fukuda
Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan. jm-mizumoto@kochi-u.ac.jp.
Hiroyuki
H
Mizumoto
Research Institute of Molecular Genetics, Kochi University, Nankoku, Kochi 783-8502, Japan. kouheio@kochi-u.ac.jp.
Kouhei
K
Ohnishi
Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan. akiba@kochi-u.ac.jp.
Akinori
A
Kiba
Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan. yhikichi@kochi-u.ac.jp.
Yasufumi
Y
Hikichi