Effect of bacterial endophyte on expression of defense genes in Indian popcorn against Fusarium moniliforme

Abstract

An endophytic Bacillus amyloliquefaciens subsp. subtilis was isolated from surface sterilized seedlings of tropical corn. To evaluate the hypothesis that this endophyte is defensive in nature and determine the mechanisms of host defense we examined the effects of the endophyte on pathogens and host disease resistance genes. The bacterial endophyte showed antifungal activity against fungal pathogens Fusarium moniliforme, Colletotrichum gloeosporioides and Aspergillus flavus. Plant protection activity was also observed in Indian popcorn seedlings inoculated with the endophyte against F. moniliforme. Gene expression analysis was conducted and demonstrated that up-regulation of several defense genes in corn was greater after 48 hours of pathogen challenge than 24 hours. Plant defense pathways triggered by the endophytic bacterium appeared to be SA (salicylic acid) independent. The abundance of the zm Jasmonic acid-induced gene expression was greater in pathogen challenged plants pre-treated with the endophytic bacterium than in the plants challenged only with pathogen. Pre-treatment with the endophytic bacterium resulted in a more intense induction of maize pathogenesis related protein genes PR-1 and PR-10 during interaction with F. moniliforme compared to plants that were treated only with the fungal pathogen. © 2015, Springer Science+Business Media Dordrecht.