Enhancing Disease Resistance in Plants and Stored Potato Tubers through Inoculation of Seed Tubers with the Endophyte Bacillus subtilis 10-4 and Genomic Analysis of its Antimicrobial Properties

Abstract

The effect of inoculation of healthy hydroponic seed mini-tubers and super-elite reproduction seed tubers with the endophytic bacterium Bacillus subtilis 10-4 on the resistance of plants and stored tubers to diseases was studied. A search for clusters of genes associated with the synthesis of antimicrobial secondary metabolites in the genome of strain 10-4 was carried out. A prolonged protective effect of 10-4 against diseases of leaves (alternariosis) and stored tubers (scab, fusarium) of potatoes was revealed. Metagenomic analysis of the ITS region showed a decrease in the species composition and the proportion of phytopathogenic fungi in plant leaves and stored tubers under the influence of 10-4 with maximum effect during inoculation of healthy mini-tubers. Using the anti-SMASH program, the gene clusters responsible for the synthesis of a wide range of secondary metabolites with antimicrobial activity (type III polyketides, nonribosomal peptide synthetases, betalactones, sactypeptides, rantipeptides, nonribosomal peptide metallophores, transAT-polyketide synthetases, and terpenes) were identified in the genome of strain 10-4. It was revealed that the main antimicrobial compounds of 10-4, which play an important role in the biocontrol of diseases and plant protection, are surfactin, fengycin, bacillibactin, bacillaene, subtilosin A, and bacilysin. In addition, using the CARD database, a wide range of antimicrobial resistance genes with different mechanisms of action were predicted in strain 10-4. In general, the method of pre-sowing treatment of healthy hydroponically grown seed mini-tubers with 10-4 increases the efficiency of bacterial inoculation and ensures long-term protection of tubers during storage and reduces the risk of disease transmission to new generations of plants.