Plasmid and pathogenicity in Xanthomonas oryzae pathovar oryzae, the bacterial blight pathogen of Oryza sativa

Abstract

Xanthomonas oryzae pv. oryzae, the causative agent for bacterial leaf blight of rice, comprises diverse groups of strains differing in biochemical and pathological characteristics. A collection of X.o. pv. oryzae strains differing in geographical origin was screened for the presence of plasmids. Out of 17 isolates of X.o. pv. oryzae, 14 harboured plasmids of which two isolates (XoP5, XoC26) had two plasmids each and one isolate (XoR20) had three. The remaining isolates contained a single plasmid of identical mobility. Finger print analysis of plasmids was carried out using Eco RI for 10 isolates. The restriction fragment pattern was distinct for each isolate. They were classified under three groups based on cluster analysis using the unweighted pair group method with averages (UPGMA). Of the 18 plasmids, the plasmid pMA36 (X.o. pv. oryzae XoC36) was further characterized. This plasmid was cured by acridine orange at the frequency rate of 10%. The cured strain was transformed with pMA36 at a frequency of 2.3 times 102 transformants μg‐1 of plasmid DNA. The plasmid‐cured strain was virulent on rice but symptom development was delayed when compared to wild and transformed strains. The wild type strain (X.o. pv. oryzae XoC36) was resistant to ampicillin, carbenicillin and rifampicin whereas the cured strain was resistant to carbenicillin and rifampicin but sensitive to ampicillin. The transformant was resistant to the three antibiotics indicating that the plasmid pMA36 codes for ampicillin resistance. The plasmid influenced the pathogenicity of X.o. pv. oryzae.

Reduced Genetic Variation Occurs among Genes of the Highly Clonal Plant Pathogen Xanthomonas axonopodis pv. vesicatoria, Including the Effector Gene avrBs2

“…vesicatoria appears to contain a higher number of plasmids than is usually observed within soil-or plant-associated bacteria. Although studies of plasmid diversity among a global sample of a particular bacterium are not common, examinations of plasmids within populations of various Pseudomonas syringae pathovars, Xanthomonas species, and Bacillus species have generally found that the bacteria carry zero, one, or two plasmids per strain (3,6,17,42,68,69,78). Still, the relatively high number of plasmids observed within X. axonopodis pv.…”

A recently collected Xanthomonas translucens isolate encodes TAL effectors distinct from older, less virulent isolates

“…Other Xt strains, including Xanthomonas translucens pv. graminis (Xtg) NCPPB3711, Xtt CIX43, Xtu CFBP2055, Xtu Km15, Xtu Lr8 and Xtu UPB513, also have plasmids, although, unlike other Xanthomonas species, their role in pathogenicity and/or host adaptation has not been described [35]. We identified 104 putative genes on the predicted plasmid, and only 25 of these have a predicted function to orthologous genes (), most of which have functions related to the T4SS and genes from the VirB family.…”

Enhanced colonization and pathogenicity of Erwinia amylovora strains transformed with the near‐ubiquitous pEA29 plasmid on pear and apple

“…michiganensis (Meletzus et al ., 1993), Xanthomonas oryzae pv. oryzae (Amuthan & Mahadevanm, 1993) and Agrobacterium tumefaciens (Nair et al ., 2003).…”