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Title
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Symbiosis-specific expression of two Medicago truncatula nodulin genes, MtN1 and MtN13, encoding products homologous to plant defense proteins.
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Authors
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P.Gamas,
F.de Billy,
G.Truchet.
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Ref.
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Mol Plant Microbe Interact, 1998,
11,
393-403.
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PubMed id
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Abstract
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Two Medicago truncatula nodulin genes putatively encoding proteins structurally
related to two classes of proteins commonly associated with plant defense
reactions have been characterized. MtN1 is homologous to two small,
cysteine-rich, pathogen-inducible proteins from pea (pI39 and pI230), whereas
MtN13 is closely related to the PR10 family of pathogenesis-related proteins. We
show that neither MtN1 nor MtN13 is induced in leaves in response to pathogenic
bacteria, and that both are exclusively expressed during nodulation. In situ
hybridization experiments as well as Northern (RNA) studies of interactions
between M. truncatula and either wild-type Rhizobium meliloti or mutants
deficient in infection establish that MtN1 is associated with the infection
process, while MtN13 represents the first specific marker described for the
nodule outer cortex. Possible roles for MtN1 and MtN13 are discussed. We also
present the identification of another member of the PR10 family, designated as
MtPR10-1, whose regulation is strikingly different from that observed for MtN13,
being constitutively expressed in roots and pathogen-inducible in leaves.
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