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Sinorhizobium meliloti -induced chitinase gene expression in Medicago truncatula ecotype R108-1: a comparison between symbiosis-specific classV and defence-related classIV chitinases

Salzer, Peter ; Feddermann, Nadja ; Wiemken, Andres ; Boller, Thomas ; Staehelin, Christian

In: Planta, 2004, vol. 219, no. 4, p. 626-638

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    Titre
    • Sinorhizobium meliloti -induced chitinase gene expression in Medicago truncatula ecotype R108-1: a comparison between symbiosis-specific classV and defence-related classIV chitinases
    Auteur
    • Salzer, Peter. Botanisches Institut der Universität Basel, Hebelstrasse 1, 4056, Basel, Switzerland
    • Feddermann, Nadja. Botanisches Institut der Universität Basel, Hebelstrasse 1, 4056, Basel, Switzerland
    • Wiemken, Andres. Botanisches Institut der Universität Basel, Hebelstrasse 1, 4056, Basel, Switzerland
    • Boller, Thomas. Botanisches Institut der Universität Basel, Hebelstrasse 1, 4056, Basel, Switzerland
    • Staehelin, Christian. Botanisches Institut der Universität Basel, Hebelstrasse 1, 4056, Basel, Switzerland
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:315288
    Summary
    The Medicago truncatula (Gaertn.) ecotypes JemalongA17 and R108-1 differ in Sinorhizobium meliloti-induced chitinase gene expression. The pathogen-inducible classIV chitinase gene, Mtchit4, was strongly induced during nodule formation of the ecotype JemalongA17 with the S. meliloti wild-type strain 1021. In the ecotype R108-1, the S. meliloti wild types Sm1021 and Sm41 did not induce Mtchit4 expression. On the other hand, expression of the putative classV chitinase gene, Mtchit5, was found in roots of M. truncatula cv. R108-1 nodulated with either of the rhizobial strains. Mtchit5 expression was specific for interactions with rhizobia. It was not induced in response to fungal pathogen attack, and not induced in roots colonized with arbuscular mycorrhizal (AM) fungi. Elevated Mtchit5 gene expression was first detectable in roots forming nodule primordia. In contrast to Mtchit4, expression of Mtchit5 was stimulated by purified Nod factors. Conversely, Mtchit4 expression was strongly elevated in nodules formed with the K-antigen-deficient mutant PP699. Expression levels of Mtchit5 were similarly increased in nodules formed with PP699 and its parental wild-type strain Sm41. Phylogenetic analysis of the deduced amino acid sequences of Mtchit5 (calculated molecular weight = 41,810Da, isoelectric point pH7.7) and Mtchit4 (calculated molecular weight 30,527Da, isoelectric point pH4.9) revealed that the putative Mtchit5 chitinase forms a separate clade within classV chitinases of plants, whereas the Mtchit4 chitinase clusters with pathogen-induced classIV chitinases from other plants. These findings demonstrate that: (i) Rhizobium-induced chitinase gene expression in M. truncatula occurs in a plant ecotype-specific manner, (ii) Mtchit5 is a putative chitinase gene that is specifically induced by rhizobia, and (iii) rhizobia-specific and defence-related chitinase genes are differentially influenced by rhizobial Nod factors and Kantigens