Actinobacteria–Plant Interactions: A Boon to Agriculture

Strap, Janice L.

doi:10.1007/978-3-642-20332-9_13

Cited by 23 publications

(13 citation statements)

References 170 publications

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“…In our study, this strain was used as positive control for enzymatic activities and for HCN production. Although in this research the HCN production by actinobacteria was negative, the production of volatile substances by many bacteria including actinomycetes have been reported, and some of these substances have been implicated as a biocontrol mechanism .…”

Section: Discussionmentioning

confidence: 61%

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes

Solans

Scervino

Messuti

et al. 2016

J. Basic Microbiol.

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Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications.

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Section: Discussionmentioning

confidence: 61%

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes

Solans

Scervino

Messuti

et al. 2016

J. Basic Microbiol.

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“…In contrast, groups such as Chloroflexi have been reported to be very slow growers ( Davis et al, 2011 ) that may rely on whatever minimal resources are available. Finally, members of the Actinobacteria, one of the predominant phyla in this study, have been reported to play an important role as organic matter decomposers ( Strap, 2011 ), which may be of key importance in maintaining microbially mediated processes when nutrients become limited after fertilization and plant uptake. Given this, we could speculate on the cooperative behavior of these groups; where at the face of nutrient depletion, Chloroflexi, as a slow grower phyla ( Davis et al, 2011 ) can thrive given the slow demand of nutrients, while Actinobacteria act as the decomposers that release the nutrients required by the fast-growers such as Proteobacteria.…”

Section: Discussionmentioning

confidence: 85%

Seasonal Changes in a Maize-Based Polyculture of Central Mexico Reshape the Co-occurrence Networks of Soil Bacterial Communities

et al. 2017

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The milpa is a traditional maize-based polyculture in Mexico that is typically practiced as rainfed agriculture. Because milpa cultivation has been practiced over a vast range of environmental and cultural conditions, this agroecosystem is recognized as an important repository of biological and cultural diversity. As for any agroecosystem, the relationship between plant development and the biogeochemical processes of the soil is critical. Although the milpa has been studied from different perspectives, the diversity and structure of microbial communities within milpa soils remain largely unexplored. In this study, we surveyed a milpa system in Central Mexico across cropping season: before planting (dry season; t1), during the early growth of plants (onset of the rainy season; t2), and before harvest (end of the rainy season; t3). In order to examine changes in community structure through time, we characterized bacterial diversity through high-throughput sequencing of 16S rRNA gene amplicons and recorded the nutrient status of multiple (5–10) soil samples from our milpa plots. We estimated microbial diversity from a total of 90 samples and constructed co-occurrence networks. Although we did not find significant changes in diversity or composition of bacterial communities across time, we identified significant rearrangements in their co-occurrence network structure. We found particularly drastic changes between the first and second time points. Co-occurrence analyses showed that the bacterial community changed from a less structured network at (t1) into modules with a non-random composition of taxonomic groups at (t2). We conclude that changes in bacterial communities undetected by standard diversity analyses can become evident when performing co-occurrence network analyses. We also postulate possible functional associations among keystone groups suggested by biogeochemical processes. This study represents the first contribution on soil microbial diversity of a maize-based polyculture and shows its dynamic nature in short-term scales.

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“…Acidobacteria are generally classified as slow-growing oligotrophs ( Fierer et al, 2007 ) and recent long- ( Yao et al, 2014 ; Eo and Park, 2016 ) and short-term ( Herzog et al, 2015 ) studies found that their abundance decreased significantly with N fertilizer application. Conversely, Actinobacteria, which represent the predominant phylum in all the soils studied and play a major role in agricultural soil quality promotion as they are remarkable organic matter decomposer ( Strap, 2011 ), were significantly more abundant in the NPK treatment than in the other soils surveyed. This result may be explained by a negative correlation between the abundance of Actinobacteria and soil pH, recently described by Li et al (2012) .…”

Section: Discussionmentioning

confidence: 96%

Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies

et al. 2016

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Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters are known to change slowly, the particularity of unchanged fertilization treatments since 1902 allows a profound assessment of linkages between management and abiotic as well as biotic soil parameters. Our study revealed that pH and TOC were the majors, while nitrogen and phosphorous pools were minors, drivers for structure and activity of the soil microbial community. Due to the long-term treatments studied, our findings likely represent permanent and stable, rather than transient, responses of soil microbial communities to fertilization.

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Actinobacteria–Plant Interactions: A Boon to Agriculture

Cited by 23 publications

References 170 publications

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes

Seasonal Changes in a Maize-Based Polyculture of Central Mexico Reshape the Co-occurrence Networks of Soil Bacterial Communities

Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies

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