Impact of soil microbiome diversity on inoculant use in wheat

Abstract

Wheat is the second most cultivated cereal in the world with an increase on its consumption every year. Considering the intensification of productive systems and the increasing dependence of pesticides, it is an urgent need to find sustainable alternatives specially for wheat crop management. In this context, the rhizosphere microbioma offers the host plant many beneficial functions including nutrient absorption, abiotic stress tolerance and defense against soil borne diseases. For instance, during a fungal invasion of a radicular pathogen, specific bacterial families and certain microbiome functions are enriched in the rhizosphere, helping to prevent plant infection by the pathogen. Although this process was partially elucidated in previous studies, it is still a limited knowledge about how soil microbiome diversity impacts the interaction between rhizosphere microbiome and pathogen or antagonist inoculant in production systems. Thus, this project aims to evaluate the rhizosphere microbiome assembly and its impact on the protection of wheat plant inoculated with the soil pathogen Bipolaris sorokiniana and with an antagonist bacterial inoculant under different conditions of soil microbiome diversity. Hence, 16S rRNA and ITS metataxonomic sequencing will be used to assess disease progress and the structure of the bacterial and fungal community in the wheat rhizosphere, considering the following treatments: 1) soil + wheat plant (control); 2) plant + isolated antagonist; 3) plant + pathogen; 4) plant + isolated antagonist + pathogen; 5) soil without plant (bulk soil). All treatments will be subjected to soil with a gradient of microbial diversity, applying the "dilution-to-extinction" technique. Besides that, the pathogen presence will be monitored through quantitative PCR (qPCR) technique, as well as the total gene quantification of 16S and 18S rRNA. Lastly, the final results will be normalized and submitted to statistics and bioinformatics analysis. Then, with this project, we hope to shed a light on a critical issue in the use of inoculants in Agriculture, which is the reason that we observe inconsistent results when it is applied inoculants in different locations or in different agricultural years. Our hypothesis is that the success of the soil inoculant establishment in the rhizosphere and its effect on the plant performance is also determined by the diversity and functionality of the soil microbiome that receives the inoculation. (AU)