Author(s): COSTA, L. S. A. S.; FARIA, M. R. de; CHIARAMONTE, J. B.; MAUCHLINE, T. H.; BETTIOL, W.; MENDES, R.

Summary: The rhizosphere is an environment influenced by a range of beneficial functions to plants such as nutrient uptake, stress tolerance, and defense against soil-borne pathogens. During the fungal invasion, a number of specifics bacterial families and function are enriched in the rhizosphere to fend off plant infection. Thus, considering that the host plant relies on the rhizosphere microbiome for protection against soil-borne pathogens, we hypothesized that plant domestication impacted this interaction between the plant and soil microbiome. Therefore, in this study, we compared wheat landraces and modern cultivars to understand the rhizobacterial community dynamics during Fusarium graminearum invasion. The disease evaluation and rhizosphere soil collection were repeated in a total of 5 cycles, in microcosm pot. Rhizosphere community structure was assessed through 16S rRNA amplicon sequencing. In addition, the population dynamics of the pathogen was investigated by DNA quantification through the qPCR technique. The disease severity index increased in all genotypes in the absence of the pathogen. However, in the presence of the pathogen the Pakintan and Cep 24 genotypes reduced the disease level and the Karakilcik and Iac 5 genotypes showed the same level of disease during the cycles. In general, the analysis of qPCR showed that the abundance of the pathogen increased over time. The principal coordinate analysis revealed that the successive cycles had an impact on the rhizobacterial community composition. The results showed a pronounced rhizosphere effect (bulk soil sample clustered separately from rhizosphere sample) and cycle effect revealing a shift in microbial communities over cycles, and more homogenous pattern in cycles 4 and 5. The taxonomic composition showed significant enrichment mainly for the phylum Acidobacteria and Choloroflexi, and reduction for the phylum Proteobacteria and Bacteroidetes over time. The results suggested that the monoculture and presence of pathogens in the soil may interfere with the recruitment of specific members of the rhizosphere microbiome which drive defense patterns. Knowledge about the reorganization of the rhizosphere microbiome against phytopathogens can provide the selection of key microorganisms and improved plant performance to recruitment beneficial microorganisms and protect the root system.

Publication year: 2019

Types of publication: Abstract in annals or event proceedings

Unit: Embrapa Environment

Keywords: Plant domestication, Plant-microbe interaction, plant protection