MtNF-YA1, A Central Transcriptional Regulator of Symbiotic Nodule Development, Is Also a Determinant of Medicago truncatula Susceptibility toward a Root Pathogen

Abstract

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 (WT) 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 WT 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.

Medicago TERPENE SYNTHASE 10 Is Involved in Defense Against an Oomycete Root Pathogen

“…In both root types, about two-thirds of the DEGs were upregulated and one-third was downregulated. These numbers are similar to those obtained after infection for 24 h (Badis et al, 2015;Rey et al, 2016). The overlay between DEGs obtained in our approach and those obtained after infection for 24 h, however, is rather small, pointing to the fact that roots responded differently to the infection with A. euteiches at these two time points (Supplemental Fig.…”

The Medicago truncatula GRAS protein RAD1 supports arbuscular mycorrhiza symbiosis and Phytophthora palmivora susceptibility

“…Forward genetics of M. truncatula identified the dual contribution of a glycerol phosphate acyl transferase gene termed RAM2 ( Reduced Arbuscular Mycorrhization 2 ) in the colonization by AM fungi and the oomycete pathogens P. palmivora ( Wang et al , 2012 ) and Aphanomyces euteiches ( Gobbato et al , 2013 ). Complementarily, reverse genetics approaches based on surveying mutants defective in symbiosis for their interaction with pathogens revealed that symbiosis-related LysM-RLK receptors, transcription factors, and hormone signalling genes may have broader functions in the associations with microbes ( Laffont et al , 2015 ; Moreau et al , 2013; Rey et al , 2013 , 2015 , 2016 ).…”

Identification of miRNAs Involved in Bacillus velezensis FZB42-Activated Induced Systemic Resistance in Maize

“…The overexpression of OsHAP2E for a CCAAT-binding factor confers resistance to Cucumber mosaic virus and Rice necrosis mosaic virus [41]. MtNF-YA1 , previously identified as a key regulator of rhizobial symbiosis establishment, is also a determinant of Medicago truncatula susceptibility toward a root pathogen [42]. In summary, our results showed that some members in the miR169 family might regulate NF-Y transcription factors to activate the ISR process.…”