Abstract
To prevent excessive nodulation, leguminous plants strictly regulate the number of root nodules. In this regulation, long distance signal that derived from shoots suppress the nodulation. A Lotus japonicus hypernodulating mutant, har1, impairs this regulation system. In the plant-pathogen interactions, pathogen infection often induces plant defense response not just locally but also at the site apart from the primary infection's to prevent the subsequent invasive attack.
In this study, we examined the effects of salicylic acid (SA) and jasmonic acid (JA), which are considered to be key factors in the systemic resistances, on the symbiotic nodulation in L. japonicus. Addition of methyl jasmonate on shoot reduced the number of root nodules in both wild type plants and har1 mutants, whereas treatments with SA had no effects. These results suggested that JA and/or JA-induced compound(s) may be a HAR1-mediated systemic signal for both symbiotic and pathogenic infections.
