Pea Broth Enhances the Biocontrol Efficacy of Lysobacter capsici AZ78 by Triggering Cell Motility Associated with Biogenesis of Type IV Pilus

Abstract

Bacterial cells can display different types of motility, due to the presence of external appendages such as flagella and type IV pili. To date, little information on the mechanisms involved in the motility of the Lysobacter species has been available. Recently, L. capsici AZ78, a biocontrol agent of phytopathogenic oomycetes, showed the ability to move on jellified pea broth. Pea broth medium improved also the biocontrol activity of L. capsici AZ78 against Plasmopara viticola under greenhouse conditions. Noteworthy, the quantity of pea residues remaining on grapevine leaves fostered cell motility in L. capsici AZ78. Based on these results, this unusual motility related to the composition of the growth medium was investigated in bacterial strains belonging to several Lysobacter species. The six L. capsici strains tested developed dendrite-like colonies when grown on jellified pea broth, while the development of dendrite-like colonies was not recorded in the media commonly used in motility assays. To determine the presence of genes responsible for biogenesis of the flagellum and type IV pili, the genome of L. capsici AZ78 was mined. Genes encoding structural components and regulatory factors of type IV pili were upregulated in L. capsici AZ78 cells grown on the above-mentioned medium, as compared with the other tested media. These results provide new insight into the motility mechanism of L. capsici members and the role of type IV pili and pea compounds on the epiphytic fitness and biocontrol features of L. capsici AZ78.

Dual RNA‐Seq of Lysobacter capsici AZ78 – Phytophthora infestans interaction shows the implementation of attack strategies by the bacterium and unsuccessful oomycete defense responses

“…) that summarizes the attack strategies implemented by Lc and their outcome on the Pi transcriptome. Specifically, genes involved in the biogenesis of T4P, external appendages that are associated with Lc cell motility (Tomada et al ., ), were up‐regulated when Lc attacked and spread over the Pi mycelium. T4P was required in human and plant pathogenic bacteria for host colonization and pathogenesis (Burrows ; Dunger et al ., ) and in L. enzymogenes C3 for colonization and infection of the phytopathogenic fungus Cryphonectria parasitica (Patel et al ., ).…”

The impact of the omics era on the knowledge and use ofLysobacterspecies to control phytopathogenic micro-organisms

“…; Tomada et al . ). However, biosynthesis of the flagellum in these strains is nonfunctional due to the lack of genes encoding essential flagellar components (de Bruijn et al .…”

“…), such as the flagellar filament encoded by fliC, which is missing in the L. capsici AZ78 genome (Tomada et al . ).…”

“…Transcriptomic analysis confirmed the involvement of type IV pili in the motility of L. capsici strains on a jellified agar medium (Tomada et al . ) and the twitching motility of L. enzymogenes cells at the margin of colonies (Wang et al . ; Zhou et al .…”

“…Most Lysobacter species have been reported as nonmotile cells lacking flagella (Christensen and Cook 1978;Siddiqi and Im 2016). Nonmotility and the absence of flagella was recently confirmed in the genomes of L. antibioticus strains, whereas genes encoding components of the flagellum apparatus were retrieved in the genomes of bacterial strains belonging to L. capsici, L. enzymogenes and L. gummosus Tomada et al 2016). However, biosynthesis of the flagellum in these strains is nonfunctional due to the lack of genes encoding essential flagellar components , such as the flagellar filament encoded by fliC, which is missing in the L. capsici AZ78 genome .…”