Impact of Bacillus subtilis UD1022 strain EPS defective (UD1022-EPS) in rhizosphere microbiome assembly in tomato plants during drought stress

• Grant number: 21/14711-2
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: March 31, 2022
• End date: February 02, 2023
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Rodrigo Mendes
• Grantee: Caroline Sayuri Nishisaka
• Supervisor: Harsh Bais
• Host Institution: Embrapa Meio-Ambiente. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). Jaguariúna , SP, Brazil
• Institution abroad: University of Delaware (UD), United States
• Associated to the scholarship: 20/06077-9 - Impact of soil microbiome diversity on inoculant use in wheat, BP.DR

Abstract

Bacillus subtilis is one of the most studied gram-positive plant growth promoters of rhizobacteria, with great agricultural and ecological importance. Its capacity to induce plant development, pathogen protection, and host abiotic stress protection are widely explored by researchers. For that, mutant gene-defective models can be created to understand the important traits associated with that fitness. This work aims to analyze the impact of a gram-positive inoculant on tomato development and rhizosphere microbiome assembly under drought conditions by using Bacillus subtilis (strain UD1022) and the respective mutant defective for exopolysaccharides (EPS) production. The bioassay will consider 60 pots, including bulk soil and plant-based treatments, which will or will not receive inoculation of wild and mutant B. subtilis, UD1022 and UD1022-EPS strains, respectively. Thus, soil sampling will be done 5 times during 20 days of the experiment, the first one is 4 days after seedling, followed by sampling in 8, 12, 16, and 20 days. Plus, the inoculations will be done after 2 days of seedling, by adding the inoculants in tomato thatch. All soil samples will have the microbiome genetic material extracted, followed by quantitative chain reaction (qPCR) of gyrB gene from B. subtilis, for inoculant track. Furthermore, all DNA samples will have the V4 region of the 16S rRNA gene and the ITS1 region of the ITS gene sequenced, using the Illumina MiSeq platform. Finally, the data analysis will include average comparisons of plant height, aerial part, and root dry mass, and gyrB number of copies averages by Tukey test (P<0.05), as well as amplicon sequence variants (ASVs) processing using Dada2 pipeline, followed by exploratory, permutational variance, and covariance analysis. (AU)