Brevibacillus sp. promotes maize root colonization by Acaulospora tuberculata and the alteration of associated plant protein responses

Abilities of rhizobacteria to promote mycorrhization of arbuscular mycorrhiza (AM) on maize roots have been documented. In this study, the rhizospheric bacterium, Brevibacillus sp. SUT47 was found to significantly promote spore number and root colonization of Acaulospora tuberculata. To understand how maize roots respond to SUT47, a comparative proteomics analysis was performed. We found that at 30 days after inoculation (dai), the proteins involved in plant defense mechanism and Reactive Oxygen Species (ROS)-scavenging enzymes were the main proteins altered in tested maize roots. Levels of salicylic acid, hydrogen peroxide, and the activity of superoxide dismutase were significantly decreased in AM+SUT47 roots at 7 dai, while the activities of peroxidase and ascorbate peroxidase increased especially in AM+SUT47 roots at 30 dai. Thus, this work showed the alteration of some plant defense-related compounds and antioxidative enzyme activities that are associated with an enhancing maize root colonization by AM when co-inoculated with SUT47.