Rhizobia dispersion by Trichoderma harzianum hyphae

ITURRALDE, ESTEBAN; COLLA, DELFINA; LUCHETTI, ABRIL; TORRES TEJERIZO, GONZALO; PEREZ GIMENEZ, JULIETA

Evento Virtual

Congreso; ISME Virtual Microbial Ecology Summit; 2020

ISME

Soybean crops are inoculated with Bradyrhizobium spp. Competition for nodulation is a problem faced by the rhizobia of the inoculant. One way to solve the problem is to improve the distribution of rhizobia in the soil, but we know that motility of bacteria is limited when soils are at field capacity. On the other hand, fungal hyphae are able to colonize soils and grow in pores that have air. It has been shown that the mycelia can be used as pathways for the active dispersal of bacteria (fungal highway). In this way, mycelial networks could play an important role dispersing the bacteria in soils at field capacity. Previously, we demonstrated the efficiency of coinoculation between Bradyrhizobium spp. and Trichoderma harzianum, in order to improve the distribution of rhizobia. We generated an in vitro system to test the fungal highway mechanism in a divided Petri dish. On one side, B. diazoefficiens USDA 110 GFP and T. harzianum were inoculated, and on the other side, a germinated seed was placed. When hyphae had reached the soybean roots the germinated seeds were planted in pots. After 21 days post inoculation, the nodules were infected and this was observed by microscopy. The bacteria could be dispersed by fungus hyphae. This could allow rhizobia to colonize other niches and thus benefit competition for nodulation. Adding T. harzianum to Bradyrhizobium spp inoculants could improve the distribution of bacteria in soil by fungal highway.