Synthesis and role of hopanoids on Methylobacterium mesophilicum SR1.6/6 colonization of the host plant

Abstract

The genera Methylobacterium is comprising by pink-pigmented facultative methylotrophic (PPFM), which are able to colonize host plant, inducing plant resistance to pathogens and promoting plant growth. In this context, only eight bacteria genome of this genus were totally sequenced and few studies has been performed in order to understand Methylobacterium-plant interaction. Proteomic study analyze the interaction between Methylobacterium extorquens (colonizing leaves phyllosphere) with Arabidopsis thaliana (model plant) reports the super expression of antioxidant system proteins and show the increase in PhyR regulator expression important on phyllosphere colonization. Moreover, on a transcriptomic study evaluating M. mesophilicum SR1.6/6- soybean (Glycine max) interaction it was observed that bacterial biofilm cell on soybean root, the super expression of genes involved in ethanol/methanol processing, on porine biosynthesis related to molecule transport, siderophores production, antioxidant system, and the hopanoids biosynthesis which confers membrane rigidity, indicating possible genes involved in the M. mesophilicum host plant interaction. Therefore, the present study aims to: 1) annotate M. mesophilicum SR1.6/6 genes involved in hopanoids biosynthesis; 2) evaluate the gene expression profile in vivo and in planta; 3) obtain defective mutants in hopanoids biosynthesis genes and 4) evaluate the establishment of this mutants on the host plant. This study can also help to comprehend the role of hopanoids in plant- endophyte interaction, seeking to increase our knowledge on the mechanisms (genetic and physiologic) involved in the interaction of Methylobacterium endophytic bacteria and plant host. Since this bacterium has being used to promote plant growth, this knowledge can allow the development of inoculants on the seedling production of different agricultural crop.