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RESEARCH PRODUCT

Impact of double symbiosis (arbuscular mycorrhiza and nodulation) on nitrogen uptake in the Papilionoideae subfamily

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description

The study of plant-microbe associations through nutrient exchanges has significantly improved our understanding of plant microbiome. Leguminous plants establish mutualistic associations with both rhizobial bacteria and arbuscular mycorrhizal fungi. These symbioses improve mineral plant nutrition and increase plant resistance against biotic and abiotic stresses. Plant-microbe associations provide key features for the current agricultural and environmental challenges.In Poaceae plant, inductions of specific ammonium transporters (AMT) genes and nitrogen/peptide transporters (NRF) genes have already been described during arbuscular mycorrhiza symbiosis. Similarly, in Papilionoideae, AMT and NRF genes were shown to be regulated in mycorrhizal roots or in nodulated roots. However, little is known, in terms of efficiency and mechanisms, about the impact of the simultaneous presence of the two symbioses on the plant's nitrogen nutrition. Especially, nitrogen translocation mechanisms from the fungal and rhizobial symbiotic interfaces to the plant are not well-defined yet. We have investigated the impact of simultaneous symbiosis on nitrogen acquisition by host plants, and in particular, whether ammonium transporters were conserved throughout evolution among Papilionoideae, and if so, whether similar patterns of expression are shared. Phylogenetic analysis has revealed an organisation of AMT gene in orthologous clusters. Considering the effect of both symbioses on genes encoding proteins involved in nitrogen uptake, we have highlighted novel positively regulated genes during arbuscular mycorrhiza and/or rhizobia symbiosis. Our results identified new key proteins from mycorrhizal and rhizobial transcriptome and gives new insights on the regulation patterns determined by plant/microbe interaction.