Characterization of citrus rhizobacterial populations under organic and conventional cultivation systems

Abstract

Studies have shown that plant growth-promoting rhizobacteria (BPCPs) have brought numerous advantages to plants both in terms of development as weel as on resilience against biotic and abiotic stresses. However, few studies were did in citrus and even less involving the prospection of potential BPCP, mainly looking for strains in environment with organic citrus production. The project aims to investigate bacterial communities with potential BPCPs in the root system of citrus plants, under organic3and conventional cultivations. The hypothesis is BPCP will be more represented in the organic production system. For this, samples of roots and soil will be collected from citrus plants conducted under these two cultivation systems and the bacterial population isolated from the root system (rhizosphere and rhizoplane) in four different culture media (R2A, TWYE, PSM and TSA 10% ). The selection of microorganisms will be carried out by morphological aspects of isolated colonies that, after grown in liquid medium in 96-well plates, will be stored under cryogenic conditions. The definition of the OTUs ("operational taxonomic unit") will be performed through sequence analysis of the V3-V9 gene 16S rRNA region obtained through Illumina sequencing. Additionally, OTUs with characteristics for plant growth promoting bacteria (BPCP), defined by comparing sequences in databases, will be evaluated in vitro for their biofilm formation capacity; phosphate solubilization; production of siderophores, exopolysaccharides (EPS) and auxin (AIA). It is expected to obtain isolates (OTUs) that can compose synthetic communities of bacteria (SymCom) to be tested in in vivo experiments on citrus plants under greenhouse conditions.