Expression ofMbR4, a TIR-NBS type of appleR Gene, confers resistance to bacterial spot disease inArabidopsis
A single disease resistance gene candidate,MbR4, was isolated from the wild-type apple speciesMalus baccta. This gene was predicted to encode motifs characteristic of the Toll Interleukin 1 Receptor (TIR) — Nucleotide Binding Site (NBS) of theR gene. Starting with an isolated cDNA clone, genomic clones were obtained via inverse polymerase chain reaction (IPCR). TheMbR4 gene has a single open reading frame (ORF) of 2178 nucleotides, a 41-b untranslated 5’ region, a 21-b untranslated 3’ region, and a predicted protein of 726 amino acids (82 kDa). Its deduced amino acid sequence resembles the N protein of tobacco and the NL25 protein of potato. Ectopic expression ofMbR4 induced enhanced resistance in transgenicArabidopsis plants against the virulent pathogen,Pseudomonas syringae pv.tomato DC3000. Microarray analysis confirmed the induction of defense-related gene expression in pathogen-free 35S::MbR4 heterologousArabidopsis plants, thereby indicating that theMbR4 gene likely activates a pathogen-independent resistance pathway, rather than a gene-for-gene pathway. Our results suggest thatMbR4 plays a role in theR gene, and may be a source of resistance for cultivated apple species.
Keywordsapple disease resistance gene TIR-NBS (Toll Interleukin 1 Receptor-Nucleotide Binding Site)
Unable to display preview. Download preview PDF.
- Crandall CS (1926) Apple breeding at the University of Illinois. III. Agric Exp Sm Bull 275: 341–600Google Scholar
- Dayton DF, Mowry JB, Hought LF, Bailey CH, Williams EB, Janick J, Emerson FH (1970) Prima: An early fall red apple with resistance to apple scab. Fruit Var Hort Dig 24: 20–22Google Scholar
- Dellagi A, Helibronn J, Avrova AO, Montesano M, Palva ET, Stewart HE, Toth IK, Cooke DE, Lyon GD, Birch PR (2000) A potato gene encoding a WRKY-like transcription factor is induced in interactions withErwinia carotovora subsp.atroseptica and Phytophthora infestans and is coregulated with class I endochitinase expression. Mol Plant Microbe Interact 13: 1092–1101PubMedCrossRefGoogle Scholar
- Dinesh-Kumar SP, Baker BJ (2000) Alternatively splicedN resistance gene transcripts: Their possible role in tobacco mosaic virus resistance. Proc Natl Acad Sci USA 5:199Google Scholar
- Lee SY, Seo JS, Rodriguez-Lanetty M, Lee DH (2003) Comparative analysis of superfamilies of NBS-encoding disease resistance gene analogs in cultivated and wild apple species. Mol Genet Genom 269: 101–108Google Scholar
- Vinatzer BA, Patocchi A, Gianfranceschi L, Tartarini S, Zhang HB, Gessler C, Sansavini S (2001) Apple contains receptor-like genes homologous to theCladospo-rium fulvum resistance gene family of tomato with a cluster of genes cosegregating with Vf apple scab resistance. Mol Plant Microbe Interact 14: 508–515PubMedCrossRefGoogle Scholar