MtNF-YA1, a central transcriptional regulator of symbiotic nodule development, is also a determinant of Medicago truncatula susceptibility toward a root pathogen

Thomas Rey (1) , Philippe Laporte (2) , Maxime Bonhomme (3) , Marie-Françoise Jardinaud (2) , Stephanie Huguet (4) , Sandrine Balzergue (4) , Bernard Dumas (5) , Andréas Niebel (2) , Christophe Jacquet (3)

1 LRSV - Laboratoire de Recherche en Sciences Végétales
2 LIPM - Laboratoire des interactions plantes micro-organismes
3 Evolution des Interactions Plantes-Microorganismes
4 IPS2 (UMR_9213 / UMR_1403) - Institut des Sciences des Plantes de Paris-Saclay
5 Interactions Microbiennes dans la Rhizosphère et les Racines

Plant NF-Y transcription factors control a wide array of biological functions enabling appropriate reproductive and developmental processes as well as adaptation to various abiotic and biotic environments. In Medicago truncatula, MtNF-YA1 was previously identified as a key determinant for nodule development and establishment of rhizobial symbiosis. Here, we highlight a new role for this protein in compatibility to Aphanomyces euteiches, a root pathogenic oomycete. The Mtnf-ya1-1 mutant plants showed better survival rate, reduced symptoms, and increased development of their root apparatus as compared to their wild-type (VVT) background A17. MtNF-YA-1 was specifically up-regulated by A. euteiches in F83005.5, a highly susceptible natural accession of M. truncatula while transcript level remained stable in A17, which is partially resistant. The role of MtNF-YA1 in F83005.5 susceptibility was further documented by reducing MtNF-YA1 expression either by overexpression of the miR169q, a microRNA targeting MtNF-YA1, or by RNAi approaches leading to a strong enhancement in the resistance of this susceptible line. Comparative analysis of the transcriptome of VVT and Mtnf-ya1-1 led to the identification of 1509 differentially expressed genes. Among those, almost 36 defense-related genes were constitutively expressed in Mtnf-ya1-1, while 20 genes linked to hormonal pathways were repressed. In summary, we revealed an unexpected dual role for this symbiotic transcription factor as a key player in the compatibility mechanisms to a pathogen.

Mots clés: Aphanomyces euteiches; symbiosis and immunity; Plant Roots; NF-Y transcription factor; plant - microorganism relationship

Mots clés: symbiose rhizobium legumineuse; medicago truncatula; analyse du transcriptome; relation plante-microorganisme; biodiversité végétale

Domaines: Biologie végétale

Thomas Rey, Philippe Laporte, Maxime Bonhomme, Marie-Françoise Jardinaud, Stephanie Huguet, et al.. MtNF-YA1, a central transcriptional regulator of symbiotic nodule development, is also a determinant of Medicago truncatula susceptibility toward a root pathogen. Frontiers in Plant Science, 2016, 7, 14 p. ⟨10.3389/fpls.2016.01837⟩. ⟨hal-01602834⟩