Articles
CHARACTERIZATION OF PSEUDOMONAS SYRINGAE PV. TOMATO POPULATIONS FOR EFFECTOR GENES
Article number
914_12
Pages
79 – 82
Language
English
Abstract
Gram negative bacteria are equipped with genes that encode effector proteins secreted into the host cell by a type III secretion system.
General role of effector proteins is the suppression of host defences.
Various avirulence proteins can function as virulence factors when the host is not able of detecting them.
Because isolates of phytopathogenic bacteria generally contain only one or few avr genes, it can be assumed that virulence is provided by sets of redundant effector genes.
Four Pseudomonas syringae pv. tomato (Pst) strains were analysed for 42 effector genes of the reference strain DC 3000. The four isolates were missing 13 effector genes in respect to DC 3000 and were very virulent on tomato but did not give any symptoms on Arabidopsis; conversely, DC3000 gave severe symptoms on Arabidopsis but very weak symptoms on tomato.
A large worldwide collection of P. syringae pv. tomato has been characterized for presence/absence of these differential effector genes.
Analyses were performed by PCR. The avirulence genes avrPto and avrRpt2 were widely distributed in Pst populations.
The gene avrRpt2 is even more common than avrPto, probably for its virulence role associated with the absence of tomato resistance genes recognizing AvrRpt2; conversely, avrPto is recognized by the PTO resistance gene in several tomato cultivars.
Also other analysed effector genes (avrPtoB, hopAA1-2, hopF2, hopG1) are widely distributed in Pst populations all over the world; conversely, avrB3 was rarely amplified.
General role of effector proteins is the suppression of host defences.
Various avirulence proteins can function as virulence factors when the host is not able of detecting them.
Because isolates of phytopathogenic bacteria generally contain only one or few avr genes, it can be assumed that virulence is provided by sets of redundant effector genes.
Four Pseudomonas syringae pv. tomato (Pst) strains were analysed for 42 effector genes of the reference strain DC 3000. The four isolates were missing 13 effector genes in respect to DC 3000 and were very virulent on tomato but did not give any symptoms on Arabidopsis; conversely, DC3000 gave severe symptoms on Arabidopsis but very weak symptoms on tomato.
A large worldwide collection of P. syringae pv. tomato has been characterized for presence/absence of these differential effector genes.
Analyses were performed by PCR. The avirulence genes avrPto and avrRpt2 were widely distributed in Pst populations.
The gene avrRpt2 is even more common than avrPto, probably for its virulence role associated with the absence of tomato resistance genes recognizing AvrRpt2; conversely, avrPto is recognized by the PTO resistance gene in several tomato cultivars.
Also other analysed effector genes (avrPtoB, hopAA1-2, hopF2, hopG1) are widely distributed in Pst populations all over the world; conversely, avrB3 was rarely amplified.
Publication
Authors
M. Zaccardelli , F. Campanile, B.A. Vinatzer
Keywords
bacterial speck, avr genes, bacterial disease, PCR, DC3000
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