Quantification of the potential biocontrol and direct plant growth promotion abilities based on multiple biological traits distinguish different groups of Pseudomonas spp. isolates

Agaras, Betina Cecilia; Scandiani, Mercedes; Luque, Alicia G.; Fernández, Luis Alfredo Rosario; Farina, Florencia; Carmona, Marcelo; Gally, Marcela; Romero, A.; Wall, Luis Gabriel; Valverde, Claudio

doi:10.1016/j.biocontrol.2015.07.003

Cited by 53 publications

(73 citation statements)

References 67 publications

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“…Assays were done by triplicate. Based on the results of the growth inhibition generated by a single isolate against all tested fungi, we calculated the antagonism potential index (API) according to Agaras et al with modifications as follows: ([ hi / h max i ])/ n ) × (number of inhibited fungi/ n ). In this formula, hi is the % inhibition of actinobacteria isolates over each of the tested fungi ( n = 5, i.e., the total number of fungi tested; i = 1–5), and h max i is the % inhibition of actinobacteria isolates with the highest antagonistic activity in the collection against each of the tested fungi.…”

Section: Methodsmentioning

confidence: 99%

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: Methodsmentioning

confidence: 99%

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

Solans

Scervino

Messuti

et al. 2016

J. Basic Microbiol.

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“…Each point corresponds to the average shoot fresh weight of plants inoculated with one given strain minus the mean shoot fresh weight of the control treatment without bacteria. Values for relative siderophore production of isolates are taken from Agaras et al (2015). Bars give standard error background of the bacteria: Using a multivariate traitbased approach, Agaras and colleagues showed that plant beneficial pseudomonads isolated from agricultural soils cluster into two different groups, with either traits linked to plant-growth promoting activity, for instance by producing hormones, or to disease suppression, such as via antibiotics production (Agaras et al 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Prior to experiments, an active culture was collected by gentle centrifugation (150×g), washed in ¼ strength Hoagland's mineral solution (Hoagland and Arnon 1950) and adjusted to a density of 120,000 individuals/mL. Nine pseudomonad isolates were chosen from a previously characterized collection retrieved from agricultural fields, of which eight isolates are described in Agaras et al (2015). The ninth isolate (SPSA5) was characterized with the same methods as being a carrier of the phlD and prnD gene (encoding for DAPG and pyrrolnitrin), while being deficient in producing phenazine, HCN, exoprotease and phospholipase (also see Table 1).…”

Section: Amoeba and Bacterial Isolatesmentioning

confidence: 99%

“…This trait matrix covers the presence of genes coding for secondary metabolites such as hydrogen cyanide (HCN), as well as in vitro semi-quantitative measurements, amongst others siderophore production (see Table 1 and Agaras et al (2015)). For each trait we set up a separate GLM of the means with bacterial effects on plant growth as response variable and target trait as predictor.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…Pythium inhibition Siderophore Relative production For details on measurement of siderophore and HCN production, see Agaras et al (2015) Fig. 2).…”

Section: Bacterial Isolatementioning

confidence: 99%

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Protozoa stimulate the plant beneficial activity of rhizospheric pseudomonads

et al. 2016

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Aims The functioning of plant-associated bacteria is strongly influenced by their interaction with other organisms. For instance, bacteria upregulate the production of secondary metabolites in presence of protozoa and we hypothesised that this interaction may contribute to plant health.Methods Here, we tested if the effect of beneficial pseudomonads on wheat growth and health is modified by coinoculation with the bacterivorous amoeba Acanthamoeba castellanii. We assessed effects of this co-inoculation in absence and presence of the root pathogen Pythium ultimum. Results In absence of amoebae, bacterial isolates had few beneficial effects and some isolates exacerbated growth inhibition by the pathogen (despite their reported beneficial effects in vitro). Effects on plant growth in absence and presence of the pathogen were negatively correlated. Co-inoculation with amoebae suppressed this relationship, leading to plant growth promotion in absence and reduction of deleterious effects in presence of the pathogen. The positive effect of amoebae in absence of the pathogen could be related to bacterial siderophore production in vitro. Conclusions Our results illustrate the discrepancy between in vitro and in vivo effects of plant beneficial bacteria. Incorporation of other rhizospheric trophic components such as protists may be a key factor to influence the plant-beneficial potential of bacteria in vivo.

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