March
2006
, Volume
19
, Number
3
Pages
240
-
249
Authors
Seiko
Makino
,
1
Akiko
Sugio
,
2
Frank
White
,
2
and
Adam J.
Bogdanove
1
Affiliations
1Department of Plant Pathology, Iowa State University, Ames, IA 50014, U.S.A.; 2Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, U.S.A.
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RelatedArticle
Accepted 3 November 2005.
Abstract
Xanthomonas oryzae pv. oryzae and the closely related X. oryzae pv. oryzicola cause bacterial blight and bacterial leaf streak of rice, respectively. Although many rice resistance (R) genes and some corresponding avirulence (avr) genes have been characterized for bacterial blight, no endogenous avr/R gene interactions have been identified for leaf streak. Genes avrXa7 and avrXa10 from X. oryzae pv. oryzae failed to elicit the plant defense-associated hypersensitive reaction (HR) and failed to prevent development of leaf streak in rice cultivars with the corresponding R genes after introduction into X. oryzae pv. oryzicola despite the ability of this pathovar to deliver an AvrXa10:Cya fusion protein into rice cells. Furthermore, coinoculation of X. oryzae pv. oryzicola inhibited the HR of rice cultivar IRBB10 to X. oryzae pv. oryzae carrying avrXa10. Inhibition was quantitative and dependent on the type III secretion system of X. oryzae pv. oryzicola. The results suggest that one or more X. oryzae pv. oryzicola type III effectors interfere with avr/R gene-mediated recognition or signaling and subsequent defense response in the host. Inhibition of R gene-mediated defense by X. oryzae pv. oryzicola may explain, in part, the apparent lack of major gene resistance to leaf streak.
JnArticleKeywords
Additional keywords:
phytopathogenic bacteria.
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© 2006 The American Phytopathological Society