Transcriptional responses of the bacterial antagonist Serratia plymuthica to the fungal phytopathogen Rhizoctonia solani

Abstract

Rhizobacteria with biocontrol ability exploit a range of mechanisms to compete successfully with other microorganisms and to ensure their growth and survival in the rhizosphere, ultimately promoting plant growth. The rhizobacterium Serratia plymuthica AS13 is able to promote oilseed rape growth and improve seedling survival in the presence of the fungal pathogen, Rhizoctonia solani AG 2-1; however, our understanding of the mechanisms underlying the antagonism of Serratia is limited. To elucidate possible mechanisms, genome-wide gene expression profiling of S. plymuthica AS13 was carried out in the presence or absence of R. solani. We used RNA sequencing methodology to obtain a comprehensive overview of Serratia gene expression in response to R. solani. The differential gene expression profiles of S. plymuthica AS13 revealed significantly increased expression of genes related to the biosynthesis of the antibiotic pyrrolnitrin (prnABCD), protease production and transporters. The results presented here provide evidence that antibiosis is a major functional mechanism underlying the antagonistic behaviour of S. plymuthica AS13.

Biotic Interactions Shape the Ecological Distributions of Staphylococcus Species

“…To determine the potential molecular mechanism(s) underlying the bacterium-fungus interaction, we used comparative genomics of each of the Staphylococcus species alone as well as transcriptomics (RNA-sequencing or RNA-seq) of cocultures. Comparative genomics can pinpoint gene sets that are unique to species/strains that might explain ecological traits specific to a species (36, 37), while RNA-seq has the power to reveal the subset of genes and pathways that may underlie the outcomes of species interactions (38, 39). …”

Transcriptomic responses of a simplified soil microcosm to a plant pathogen and its biocontrol agent reveal a complex reaction to harsh habitat

“…Molecular interactions between biocontrol agents and target pathogens have mainly been studied in dual culture assays [2, 7, 8, 10, 18] and little is known about the more intricate molecular interplay of a complex microbial community. Microorganisms can sense and respond to the presence of neighbouring strains in the environment and alter their behaviour and performance accordingly [69].…”

“…Transcriptional changes of the growth- and morphology-related genes of plant pathogens in response to antagonistic bacteria are known to be linked to stress responses [2], and they could be proposed as markers of competitive interactions among the microbiota. Two flagellar transcriptional regulators (Rmet_1690 and Rmet_1691) were downregulated in response to T. atroviride introduction, and chemotactic motility genes were modulated in Collimonas fungivorans and Serratia plymuthica incubated with A. niger [8] and R. solani [10], respectively. Taken together, these expression profiles reflected the reaction of the simplified soil microcosm to the competition displayed by the biocontrol agent T. atroviride through antagonism and production of toxic molecules.…”

“…Molecular interplay between soil microorganisms has mainly been studied in dual cultures of plant pathogens and biocontrol agents [2, 7–10]. Soil phytopathogenic fungi cause severe diseases in several crops, and Armillaria spp.…”

“…have been extensively studied using several approaches, including transcriptomics [17]. Most transcriptomic studies of microbial biocontrol mechanisms have focused on molecular responses of the biocontrol agent and the target plant pathogen in dual cultures [2, 7, 8, 10, 18]. However, microbial properties in complex consortia often differ from those of their single components [19].…”