Understanding the mode of action of the symbiosis-specific NF-YA1 transcription factor in Medicago truncatula

RÍPODAS, CAROLINA; ARIEL, FEDERICO; LEPAGE, AGNES; COUTANT, EVE; REGAD, FARID; NIEBEL, ANDREAS

Paris

Simposio; AgreenSkills 4th Annual meeting 2017; 2017

Plants belonging to the legume family are able to interact symbiotically with nitrogen fixing bacteria named rhizobia, allowing these plants to grow in agricultural systems with low nitrogen inputs and thus to be important actors of sustainable agriculture. This symbiotic interaction leads to the formation of a new organ on the roots of the host plants, called nodule, inside which N2 is fixed for the benefit of the plant. Nodule development is specifically controlled by the nuclear factor Y (NF-Y) transcription factor NF-YA1. The heterotrimeric NF-Y complex is composed of the DNA-binding subunit NF-YA associated with two histone-like subunits NF-YB and NF-YC. Interestingly NF-Y is both a sequence specific transcription factor, binding CCAAT boxes, but also shows nucleosome-like properties, promoting chromatin accessibility for other master transcription factors. Indeed, NF-YA1 of Medicago truncatula is rapidly, strongly and specifically expressed during nodule development, and knock-out mutant lines only form few small nodules that lack a functional meristem. The aim of this project is to thoroughly understand the mode of action of MtNF-YA transcription factors in nodule development. We will determine using ChIP-Seq the binding sites for this transcription factor during nodule development. In addition, comparative transcriptome analysis using RNA-Seq in WT, mutant and overexpression backgrounds are being performed. The combination of these approaches will identify direct target genes of NF-Y complexes. Data generated in this project could help defining new strategies to promote better nodule development in legume crops during adverse conditions and to transfer nodule development into non-nitrogen-fixing crops thereby contributing to the ongoing worldwide effort to increase biological nitrogen fixation in agriculture.