Abstract
Leguminous plants form nodules and establish symbiosis with rhizobia. Inverted Repeat Lacking Clade (IRLC) legumes form indeterminate nodules. Rhizobia in nodules (bacteroids) of IRLC legumes show morphological and physiological changes compared to free-living bacteria. It is suggested that the differentiation of bacteroids are induced by Nodule specific Cysteine Rich peptides (NCRs) derived from host plants. Lotus japonicus, Glycine max, and Phaseolus vulgaris, which do not belong to IRLC, form determinate nodules, in which characteristics of bacteroids are as same as cultured bacteria, and NCRs do not exist. Leucaena glauca is a species branched early taxonomically in legumes and forms indeterminate nodule. However, characteristics of bacteroids in L. glauca are not investigated. In this study, microscopic observation and detection of NCRs in L. glauca bacteroids were performed to discuss about relations between nodule type, bacteroid characteristics and NCRs. Drastic changes of bacteroids like as IRLC legumes were not observed, and NCR peptides were not detected in L. glauca. These results suggest that the bacteroidal differentiation by NCR peptides is specific to IRLC legumes.
