THE EFFECT OF RHIZOPHAGUS IRREGULARIS AND MESORHIZOBIUM LOTI CO-INOCULATION ON LOTUS JAPONICUS

Abstract

Plants establish symbiotic relationships with soil bacteria or fungi, which colonize the plant root and provide the plant with inorganic nutrients, in exchange for photosynthesis products. Legume plants associate with both arbuscular mycorrhizal fungi (AMF) and the nitrogen-fixing soil bacteria called rhizobia. During the legume-rhizobium symbiosis, biological nitrogen fixation takes place in specific plants organs formed on the root, called nodules. Using the model legume Lotus japonicus, we studied the establishment of the legume-rhizobia-AMF tripartite symbiosis. We examined how the AM fungus Rhizophagus irregularis and the rhizobium Mesorhizobium loti affected one another during the colonization of the same legume roots, by performing co-inoculations. Moreover, we monitored the effect of the co-inoculation on the general plant performance. According to our results, the presence of M. loti had no effect on the root colonization by R. irregularis. However, root colonization by R. irregularis had a positive effect on the formation of root nodules. This study aims to enhance our understanding on how the plant selects, combines and controls its symbionts, towards to a more efficient use of legume plants in agroecosystems.

Keywords

• tripartite symbiosis, plant-microbe interactions, legumes, arbuscular mycorrhizal fungi, rhizobium