Affiliation:
1. School of Agricultural Biotechnology, Seoul National University, Suwon 441-744
2. Antibiotics Research Laboratory, Korea Research Institute of Bioscience and Biotechnology, Daejon 305-600, Korea
Abstract
ABSTRACT
We sequenced an approximately 29-kb region from
Xanthomonas axonopodis
pv. glycines that contained the Hrp type III secretion system, and we characterized the genes in this region by Tn
3-gus
mutagenesis and gene expression analyses. From the region,
hrp
(hypersensitive response and pathogenicity) and
hrc
(
hrp
and conserved) genes, which encode type III secretion systems, and
hpa
(
hrp
-associated) genes were identified. The characteristics of the region, such as the presence of many virulence genes, low G+C content, and bordering tRNA genes, satisfied the criteria for a pathogenicity island (PAI) in a bacterium. The PAI was composed of nine
hrp
, nine
hrc
, and eight
hpa
genes with seven plant-inducible promoter boxes. The
hrp
and
hrc
mutants failed to elicit hypersensitive responses in pepper plants but induced hypersensitive responses in all tomato plants tested. The Hrp PAI of
X. axonopodis
pv. glycines resembled the Hrp PAIs of other
Xanthomonas
species, and the Hrp PAI core region was highly conserved. However, in contrast to the PAI of
Pseudomonas syringae
, the regions upstream and downstream from the Hrp PAI core region showed variability in the xanthomonads. In addition, we demonstrate that HpaG, which is located in the Hrp PAI region of
X. axonopodis
pv. glycines, is a response elicitor. Purified HpaG elicited hypersensitive responses at a concentration of 1.0 μM in pepper, tobacco, and
Arabidopsis thaliana
ecotype Cvi-0 by acting as a type III secreted effector protein. However, HpaG failed to elicit hypersensitive responses in tomato, Chinese cabbage, and
A. thaliana
ecotypes Col-0 and Ler. This is the first report to show that the harpin-like effector protein of
Xanthomonas
species exhibits elicitor activity.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
121 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献