Characterization of Actinobacterial Strains as Potential Biocontrol Agents against Macrophomina phaseolina and Rhizoctonia solani, the Main Soil-Borne Pathogens of Phaseolus vulgaris in Cuba

Abstract

Macrophomina phaseolina and Rhizoctonia solani are considered two major soil-borne pathogens of Phaseolus vulgaris in Cuba. Their management is difficult, not only due to their intrinsic biology as soil-borne pathogens, but also because the lack of active ingredients available against these pathogens. Actinobacteria, a heterogeneous bacterial group traditionally known as actinomycetes have been reported as promising biological control agents (BCAs) in crop protection. Thus, the main objective of this study was to evaluate the effectiveness of 60 actinobacterial strains as BCAs against M. phaseolina and R. solani in vitro by dual culture assays. The most effective strains were characterized according to their cellulolytic, chitinolytic and proteolytic extracellular enzymatic activity, as well as by their morphological and biochemical characters in vitro. Forty and 25 out of the 60 actinobacteria strains inhibited the mycelial growth of M. phaseolina and R. solani, respectively, and 18 of them showed a common effect against both pathogens. Significant differences were observed on their enzymatic and biochemical activity. The morphological and biochemical characters allow us to identify all our strains as species belonging to the genus Streptomyces. Streptomyces strains CBQ-EA-2 and CBQ-B-8 showed the highest effectiveness in vitro. Finally, the effect of seed treatments by both strains was also evaluated against M. phaseolina and R. solani infections in P. vulgaris cv. Quivicán seedlings. Treatments combining the two Streptomyces strains (CBQ-EA-2 + CBQ-B-8) were able to reduce significantly the disease severity for both pathogen infections in comparison with the non-treated and inoculated control. Moreover, they showed similar effect than that observed for Trichoderma harzianum A-34 and with Celest® Top 312 FS (Syngenta®; Basilea, Switzerland) treatments, which were included for comparative purposes.

Using Fungi and Bacteria as Biological Control Agents of Fungal Plant Diseases an article

“…Phaseolus vulgaris infections with Macrophomina phaseolina and Rhizoctonia solani were reduced by several strains of Streptomyces CBQ-EA-2 and CBQ-B-8, which have chitinolytic, cellulolytic, and proteolytic activity. , may have a mycoparasitic potential, and these hydrolases may also play a role in the limitation of plant diseases [67].…”

A Rhizobacterium, Streptomyces albulus Z1-04-02, Displays Antifungal Activity against Sclerotium Rot in Mungbean

“…Streptomyces sp. produced cellulolytic, chitinolytic, and proteolytic extracellular enzymes that inhibit Macrophomena phaseolina and Rhizoctonia solani in Phaseolus vulgaris [ 18 ]. Furthermore, Streptomyces sp.…”

A Scientometric and Bibliometric Analysis for Actinomycetes Research - Current Status and Future Trends

“…Actinomycetes, a group of prokaryotes, are filamentous bacteria (Shahidi Bonjar et al, 2006a;Barreto et al, 2008;Tedsree & Tanasupawat, 2021;Díaz-Díaz et al, 2022), which have the enormous composition of cytosine and guanine in their DNA (Tedsree & Tanasupawat, 2021). These bacteria, also known as aerobic and able to form mycelium (Barreto et al, 2008), are found in soil and the rhizosphere and colonize the root surface (Shahidi Bonjar et al, 2006b).…”

“…Actinomycetes are known to be capable of reducing pathogen activities, such as inhibitory activity of mycelial growth of B. cinerea on tomatoes by 52.38% to 96.19% (Lahmyed et al, 2021); in vitro inhibition up to 85% hyphal desegregation, and antibacterial activity against soilborne-pathogens on Solanum lycopersicum and Daucus carota (Djebaili et al, 2021); development suppression of Alternaria brassicicola on cabbage with increases of ≥80% protection level compared to control (Hassan et al, 2017); reduce damping-off incidence of Pythium aphanidermatum in cucumber by up to 71% (Costa et al, 2013); and inhibit mycelial growth of Fusarium solani by up to 70% (Torres-Rodriguez et al, 2022). These pathogen suppressing activities are caused by their ability to produce several enzymes, i.e., amylase, protease, cellulase, chitinase, esterases, and lecithinase (Loliama et al, 2013;Lahmyed et al, 2021;Zulfa et al, 2021;Díaz-Díaz et al, 2022). In addition, they also produce antibiotics, antifungal substances, plant growth factors (Zulfa et al, 2021), siderophores, kaempferol, isoscutellarin, umbelliferone, and Cichoriin (Jaber & Fayyadh, 2019).…”

“…Several studies related to the use of Streptomyces as a biocontrol agent include: the use of Streptomyces to inhibit Ganoderma sp. (Zulfa et al, 2021), Alternaria brassicicola on cabbage seedlings (Hassan et al, 2017), charcoal rot disease on cowpea and mungbean (Jaber & Fayyadh, 2019), damping-off disease in cucumber (Costa et al, 2013), Macrophomina phaseolina and Rhizoctonia solani on Phaseolus vulgaris (Díaz-Díaz et al, 2022), Fusarium solani from tomato (Torres-Rodriguez et al, 2022), etc. In contrast, there is currently relatively little research on actinomycetes from Indonesia.…”