Modulation of the interaction among growth promoting bacteria and corn by the quorum sensing system

Abstract

The corn is one of the most important in the world and also the Brazilian economy, which exported nearly 32 million tons in 2015. However, this culture requires an intense amount of chemical fertilizers, such as nitrogen. One of the alternatives to reduce the consumption of chemical nitrogen is the use of nitrogen fixing bacteria, such as Azospirillum brasilense case, already used commercially in corn. But we know that the microorganisms do not act alone, both on the ground and inside the plant there are millions of bacteria interacting in complex ways. In the search for other microorganisms capable of performing a similar task, the Bacillus sp. strain (RZ2MS9), isolated from the rhizosphere of guarana is reported as a promoter of plant growth in crops of corn and soybeans. But still there are few studies about the process of bacteria-plant interaction. Furthermore, a study with the RZ2MS9 strain, co-inoculated with Azospirillum brasilense (Ab-v5), showed positive results as to promote growth of corn, supporting the idea that co-inoculation with different microorganisms can further improve more plant development. This response to co-inoculation can be directly related to quorum sensing system (QS), the system communication between the bacteria, which is key to population control of bacterial species, in addition to control the formation of biofilms and regular various behaviors. Faced with this panorama, this project aims to monitor the lineage of the colonization process RZ2MS9 tagged with GFP in corn, in order to better understand the bacteria-plant interaction. Furthermore, from the silencing aiiA gene related to the QS system RZ2MS9 strain, is a study on influence during the process of colonization and plant growth promotion in maize, compared to co-inoculation of RZ2MS9 with the strains Azospirillum brasilense (Ab-v5) and Burkholderia ambifaria (RZ2MS16) also reported to promote plant growth of corn. (AU)