Herbicolin A production and its modulation by quorum sensing in aPantoea agglomeransrhizobacterium bioactive against a broad spectrum of plant‐pathogenic fungi

Abstract

Global population growth makes it necessary to increase agricultural production yields.However, climate change impacts and diseases caused by plant pathogens are challenging modern agriculture. Therefore, it is necessary to look for alternatives to the excessive use of chemical fertilizers and pesticides. The plant microbiota plays an essential role in plant nutrition and health, and offers enormous potential to meet future challenges of agriculture. In this context, here we characterized the antifungal properties of the rhizosphere bacterium Pantoea agglomerans 9Rz4, which is active against a broad spectrum of plant pathogenic fungi. Chemical analyses revealed that strain 9Rz4 produces the antifungal herbicolin A and its biosynthetic gene cluster was identified and characterized. We found that the only acyl-homoserine lactone-based quorum sensing system of 9Rz4 modulates herbicolin A gene cluster expression. No role of plasmid carriage in the production of herbicolin A was observed. Plant assays revealed that herbicolin A biosynthesis does not affect the root colonization ability of P. agglomerans 9Rz4. Current legislative restrictions are aimed at reducing the use of chemical pesticides in agriculture, and the results derived from this study may lay the foundations for the development of novel biopesticides from rhizosphere microorganisms.

Interaction of bacteriophage P1 with an epiphytic Pantoea agglomerans strain—the role of the interplay between various mobilome elements

“…They can often be found among plant endophytes or epiphytes, playing a beneficial bioprotective role, but some of them are plant pathogens causing galls, wilting, soft rot, and necrosis in a variety of agriculturally relevant plants (Lindow et al, 1998 ; Walterson and Stavrinides, 2015 ). Certain strains of P. agglomerans inhibit the growth of bacteria or fungi pathogenic to plants by competition, production of antibiotics, cell wall-degrading enzymes, siderophores, hydrogen cyanide, and by the induction of systemic resistance (Wilson and Lindow, 1994 ; Thissera et al, 2020 ; Carobbi et al, 2022 ; Xu et al, 2022 ; Matilla et al, 2023 ; reviewed by Lorenzi et al, 2022 ). Phylogenetic analysis based on the sequences of 16S rDNA and fusA, gyrB, leuS, pyrG, rplB , and rpoB genes revealed a high similarity between P. agglomerans and E. coli —a hallmark of common ancestry of these two bacterial species (Delétoile et al, 2009 ).…”