Publications des agents du Cirad

Cirad

The pathogenesis-related protein PR-4b from Theobroma cacao presents RNase activity, Ca2+ and Mg2+ dependent-DNase activity and antifungal action on Moniliophthora perniciosa

Menezes S.P., De Andrade Silva E.M., Lima E.M., Oliveira de Sousa A., Andrade B.S., Santos Lima L., Gramacho K.P., Da Silva Gesteira A., Priminho Pirovani C., Micheli F.. 2014. BMC Plant Biology, 14 (161) : 21 p..

Background: The production and accumulation of pathogenesis-related proteins (PR proteins) in plants in response to biotic or abiotic stresses is well known and is considered as a crucial mechanism for plant defense. A pathogenesis-related protein 4 cDNA was identified from a cacao-Moniliophthora perniciosa interaction cDNA library and named TcPR-4b. Results: TcPR-4b presents a Barwin domain with six conserved cysteine residues, but lacks the chitin-binding site. Molecular modeling of TcPR-4b confirmed the importance of the cysteine residues to maintain the protein structure, and of several conserved amino acids for the catalytic activity. In the cacao genome, TcPR-4b belonged to a small multigene family organized mainly on chromosome 5. TcPR-4b RT-qPCR analysis in resistant and susceptible cacao plants infected by M. perniciosa showed an increase of expression at 48 hours after infection (hai) in both cacao genotypes. After the initial stage (24-72 hai), the TcPR-4b expression was observed at all times in the resistant genotypes, while in the susceptible one the expression was concentrated at the final stages of infection (45-90 days after infection). The recombinant TcPR-4b protein showed RNase, and bivalent ions dependent-DNase activity, but no chitinase activity. Moreover, TcPR-4b presented antifungal action against M. perniciosa, and the reduction of M. perniciosa survival was related to ROS production in fungal hyphae. Conclusion: To our knowledge, this is the first report of a PR-4 showing simultaneously RNase, DNase and antifungal properties, but no chitinase activity. Moreover, we showed that the antifungal activity of TcPR-4b is directly related to RNase function. In cacao, TcPR-4b nuclease activities may be related to the establishment and maintenance of resistance, and to the PCD mechanism, in resistant and susceptible cacao genotypes, respectively. (Résumé d'auteur)

Mots-clés : amélioration des plantes; résistance aux maladies; résistance génétique; physiologie végétale; phylogénie; séquence nucléotidique; arbre fruitier; modèle végétal; génie génétique; expression des gènes; moniliophthora; theobroma cacao; brésil; moniliophthora perniciosa

Thématique : Maladies des plantes; Génétique et amélioration des plantes

Documents associés

Article de revue

Agents Cirad, auteurs de cette publication :