Cropping History Effects on Pathogen Suppressive and Signaling Dynamics in Streptomyces Communities

Abstract

Diseases remain a yield-limiting factor for crops despite the availability of control measures for many pathogens. Indigenous soil microorganisms can suppress some plant pathogens, yet there is little systematic information on the effects of cropping systems on disease-suppressive populations in soil. Streptomyces have been associated with suppression of plant diseases in several naturally occurring disease-suppressive soils. Pathogen-suppressive activity of Streptomyces communities is correlated with higher bacterial densities and with inhibitory phenotypes, driven by competition among indigenous soil bacteria. We sought to characterize relationships between cropping practices and pathogen suppression among soil Streptomyces. We evaluated bacterial and Streptomyces densities and inhibitory activities in soils from a long-term crop rotation experiment. Signaling interactions that altered inhibitory phenotypes among sympatric populations were also evaluated for a subset of samples. Soils from longer rotations, which had a higher number of plant species over time, had larger bacterial and Streptomyces densities, and more inhibitors than soils from shorter rotations. In addition, signaling occurred more frequently among isolates from higher-density communities. Our work shows that bacterial density, pathogen suppression and signaling are interrelated and are affected by crop rotation, suggesting the potential for management to optimize suppressive populations.

Biological Control Agents Against Fusarium Wilt of Banana

“…From a historical perspective, biocontrol of FWB has been studied for more than 70 years (Thaysen and Butlin, 1945). Studies have reported that disease suppressive sites showed microbial communities displaying higher richness and diversity (Shen et al, 2015b; Köberl et al, 2017), and possibly a higher number of antagonistic members, as observed for streptomycetes (Kinkel et al, 2012; Jauri et al, 2017). Moreover, differences in the composition of these communities correlated with the disease suppressiveness (abundance of Acidobacteria ) or conduciveness (abundance of Bacteroidetes ) of soil (Shen et al, 2015b).…”

Core Rhizosphere Microbiomes of Dryland Wheat Are Influenced by Location and Land Use History

“…Microbial diversity is often suggested to be critical for crop productivity (41), where more diverse microbial communities are more resilient to disturbance and are better able to provide ecosystem services such as C and N cycling and disease protection (42,43). Moreover, more diverse cropping histories can significantly enhance soil microbial diversity and plant-beneficial functions (44,45). The greater diversity of bacteria and fungi in both wheat rhizospheres and bulk soils when the soils had a history of CRP participation versus no-till cropping likely reflects the greater diversity of plant communities in the CRP that support more diverse soil communities (46).…”

Bacterial, archaeal and micro-eukaryotic communities characterize a disease-suppressive or conducive soil and a cultivar resistant or susceptible to common scab

“…Above that, bacterial interaction networks hypothesized from co-occurrence data were more complex, but those may be differently affected by predation and competition of organisms at higher trophic levels depending on soil conditions and climate. Suppressive bacterial communities were comprised of specific antinobacteria and/or streptomycetes, which is consistent with their antibiotic activities but also production of siderophores enabling better acquisition of iron and other metals 43,44 .…”