Induced systemic resistance against XXXX by Micromonospora strains isolated from root nodules.

@entity1568 @entity7214 @entity14261 @entity523 @entity942
Micromonospora is a Gram positive bacterium that can be isolated from @entity1568 fixing nodules from healthy leguminous plants, where they could be beneficial to the plant. Their plant growth promoting activity in legume and non-legume plants has been previously demonstrated. The present study explores the ability of Micromonospora strains to control fungal pathogens and to stimulate plant immunity. Micromonospora strains isolated from surface sterilized nodules of alfalfa showed in vitro antifungal activity against several pathogenic fungi. Moreover, root inoculation of @entity523 plants with these Micromonospora strains effectively reduced leaf infection by the fungal pathogen @entity14261 , despite spatial separation between both microorganisms. This induced systemic resistance, confirmed in different @entity523 cultivars, is long lasting. Gene expression analyses evidenced that Micromonospora stimulates the plant capacity to activate defense mechanisms upon pathogen attack. The defensive response of @entity523 plants inoculated with Micromonospora spp. differs from that of non-inoculated plants, showing a stronger induction of @entity7214 -regulated defenses when the plant is challenged with a pathogen. The hypothesis of jasmonates playing a key role in this defense priming effect was confirmed using defense-impaired @entity523 mutants, since the @entity942 was unable to display a long term induced resistance upon Micromonospora spp. inoculation. In conclusion, nodule isolated Micromonospora strains should be considered excellent candidates as biocontrol agents as they combine both direct antifungal activity against plant pathogens and the ability to prime plant immunity.
