Distinct genetic basis for root responses to lipo-chitooligosaccharide signal molecules from different microbial origins

Abstract Lipo-chitooligosaccharides (LCOs) were originally found as symbiotic signals called Nod Factors (Nod-LCOs) controlling the nodulation of legumes by rhizobia. More recently, LCOs also in fungi and, more surprisingly, very widely kingdom Fungi, including saprophytic and pathogenic fungi. The LCO-V(C18:1, fucosylated/methyl fucosylated), hereafter Fung-LCOs, are LCO structures most commonly This raises question how legume plants such Medicago truncatula can discriminate between Nod-LCOs Fung-LCOs. To address this question, we performed a genome-wide association study on 173 natural accessions M. truncatula, using root branching phenotype newly developed local score approach. Both Fung-LCOs stimulated accessions, but responses to these two types molecules not correlated. In addition, heritability response was higher for than We identified 123 loci Nod-LCO 71 Fung-LCO responses, which only one common. suggests that both control use different molecular mechanisms. tighter genetic constraint possibly reflects ancestral origin biological activity molecules.