July
2002
, Volume
15
, Number
7
Pages
637
-
646
Authors
Eric
Marois
,
Guido
Van den Ackerveken
,
and
Ulla
Bonas
Affiliations
Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
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RelatedArticle
Accepted 7 March 2002.
Abstract
Xanthomonas campestris pv. vesicatoria bacteria expressing the type III effector protein AvrBs3 induce a hypersensitive response in pepper plants carrying the resistance gene Bs3. Here, we report that infection of susceptible pepper and tomato plants leads to an AvrBs3-dependent hypertrophy of the mesophyll tissue. Agrobacterium-mediated transient expression of the avrBs3 gene in tobacco and potato plants resulted in a similar phenotype. Induction of hypertrophy was shown to depend on the repeat region, nuclear localization signals, and acidic transcription activation domain (AAD) of AvrBs3, suggesting that the effector modulates the host's transcriptome. To search for host genes regulated by AvrBs3 in an AAD-dependent manner, we performed a cDNA-amplified fragment length polymorphism analysis of pepper mRNA populations. Thirteen AvrBs3-induced transcripts were identified and confirmed by reverse transcriptase-poly-merase chain reaction. Sequence analysis revealed homologies to auxin-induced and expansinlike genes, which play a role in cell enlargement. These results suggest that some of the AvrBs3-induced genes may be involved in hypertrophy development and that xanthomonads possess type III effectors that steer host gene expression.
JnArticleKeywords
Additional keywords:
avirulence
,
bacterial spot disease
,
SAUR (small auxin up RNA)
,
transcription factor
,
upa (upregulated by AvrBs3)
.
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ArticleCopyright
© 2002 The American Phytopathological Society