Interrelationships between Rhizobium etli G12 and Glomus intraradices and multitrophic effects in the biological control of the root-knot nematode Meloidogyne incognita on tomato.

摘要

The plant health promoting rhizobacterium Rhizobium etli G12 known to induce resistance toward root-knot nematodes was shown to increase mycorrhizal establishment when introduced in combination. R. etli promoted the establishment of Glomus intraradices on roots of different tomato cultivars. In vitro studies demonstrated that inoculation with bacteria leads to changes in fungal morphology, including increased hyphal diameter and branching as well as formation of new spores. R. etli seems to be responsible for accelerated arbuscular mycorrhizal (AMF) establishment in tomato roots in concomitant inoculation tests. Therefore R. etli is regarded to be a mycorrhiza helper bacterium. Combined inoculation of R. etli with G. intraradices in biocontrol of Meloidogyne incognita on tomato led to additive effects. Single inoculation of the microorganisms reduced galling by 24 to 39% while dual inoculation resulted in a 60% reduction. The present findings indicate that specific combinations of plant health promoting microorganisms with AMF could lead to improved mycorrhizal colonization and together act as powerful tools in the promotion of both plant growth and health.