Open AccessDowny Mildew Resistance in Arabidopsis by Mutation of HOMOSERINE KINASE
Author(s) -
Mireille van Damme,
Tieme Zeilmaker,
Joyce Elberse,
Annemiek Andel,
Monique de Sain-van der Velden,
Guido Van den Ackerveken
Publication year - 2009
Publication title -
the plant cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.324
H-Index - 341
eISSN - 1532-298X
pISSN - 1040-4651
DOI - 10.1105/tpc.109.066811
Subject(s) - biology , arabidopsis , homoserine , mutant , downy mildew , arabidopsis thaliana , powdery mildew , plant disease resistance , amino acid , wild type , genetics , biochemistry , gene , botany , virulence , quorum sensing
Plant disease resistance is commonly triggered by early pathogen recognition and activation of immunity. An alternative form of resistance is mediated by recessive downy mildew resistant 1 (dmr1) alleles in Arabidopsis thaliana. Map-based cloning revealed that DMR1 encodes homoserine kinase (HSK). Six independent dmr1 mutants each carry a different amino acid substitution in the HSK protein. Amino acid analysis revealed that dmr1 mutants contain high levels of homoserine that is undetectable in wild-type plants. Surprisingly, the level of amino acids downstream in the aspartate (Asp) pathway was not reduced in dmr1 mutants. Exogenous homoserine does not directly affect pathogen growth but induces resistance when infiltrated in Arabidopsis. We provide evidence that homoserine accumulation in the chloroplast triggers a novel form of downy mildew resistance that is independent of known immune responses.
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