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RESEARCH PRODUCT

Search for potassium transport systems involved in arbuscular mycorrhiza-rice symbiotic interactions

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Arbuscular mycorrhizal fungi (AMF) develop interdependent connections with roots of about90% of plant species. These interactions increase availability as well as translocation ofnutrients (especially N and P), and thereby improve plant nutrition and growth. Moreover,resistance to a variety of stresses, among which salt stress, has been shown to be improved byAMF-plant interactions, for example in rice. Intense research to explain the molecularmechanisms of AMF-plant beneficial interactions led to the identification of phosphate andammonium transporters involved in nutrient exchanges from AMF to the plant, in several plantspecies. In spite of the importance of potassium (K+) for plant physiology, the contribution ofAMF symbiosis to plant K+ nutrition has been little documented. Over-expression of plant K+transporters has been described in Lotus japonicus and tomato in condition of AMF symbiosis.Furthermore, K+ transport systems in the AMF Rhizophagus irregularis have been identified insilico. Here, K+ nutrition in rice colonized by R. irregularis has been analyzed at molecular andphysiological levels. Surprisingly, major K+ transport systems in rice were down-regulated uponAMF interactions, suggesting strong increase in K+ availability for uptake by root cells insymbiotic conditions. Role of K+ in the relationships between rice and R. irregularis will also bediscussed