The resistance of peanut to soil-borne pathogens improved by rhizosphere probiotics under calcium treatment

Peanut (Arachis hypogaea L.) is an important oil and economic crop. Calcium modulates plants in response to abiotic stresses and improves plant resistance to pathogens. Enrichment of beneficial microorganisms in the rhizosphere is associated with plant disease resistance and soil development. The purpose of this study was to analyze the differences in peanut rhizosphere microbial community structure between the calcium treatment and the control during two growth stages and to explain why calcium application could improve the resistance of peanuts to soil-borne pathogens. The 16S rDNA amplicon sequencing of rhizosphere microbiome showed that calcium application significantly enriched Serratia marcescens and other three dominant strains at the seedling stage. At the pod filling stage, ten dominant stains such as Sphingomonas changbaiensis and Novosphingobium panipatense were enriched by calcium. Serratia marcescens aseptic fermentation filtrate was mixed with PDA medium and inoculated with the main soil-borne pathogens in the seedling stage, which could inhibit the growth of Fusarium solani and Aspergillus flavus. The aseptic fermentation filtrate of Novosphingobium panipatense was mixed with PDA medium and inoculated with the main soil-borne pathogens in the pod filling stage, which could inhibit the growth of Sclerotium rolfsii and Leptosphaerulina arachidicola. Calcium application increases the resistance of peanuts to soil-borne pathogens by enriching them with specific dominant bacteria.