Isolation and characterization of antagonistic fungi against potato scab pathogens from potato field soils

Abstract

Potato scab is a serious plant disease caused by several Streptomyces sp., and effective control methods remain unavailable. Although antagonistic bacteria and phages against potato scab pathogens have been reported, to the best of our knowledge, there is no information about fungi that are antagonistic to the pathogens. The aim of this study was to isolate fungal antagonists, characterize their phylogenetic positions, determine their antagonistic activities against potato scab pathogens, and highlight their potential use as control agents under lower pH conditions. Fifteen fungal stains isolated from potato field soils were found to have antagonistic activity against three well-known potato scab pathogens: Streptomyces scabiei, Streptomyces acidiscabiei, and Streptomyces turgidiscabiei. These 15 fungal strains were phylogenetically classified into at least six orders and nine genera based on 18S rRNA gene sequencing analysis. These fungal isolates were related to members of the genera Penicillium, Eupenicillium, Chaetomium, Fusarium, Cladosporium, Mortierella, Kionochaeta, Pseudogymnoascus, and Lecythophora. The antagonistic activities of most of the fungal isolates were highly strengthened under the lower pH conditions, suggesting the advantage of combining their use with a traditional method such as soil acidification. This is the first report to demonstrate that phylogenetically diverse fungi show antagonistic activity against major potato scab pathogens. These fungal strains could be used as potential agents to control potato scab disease.

Short-Term Effects of Different Organic Amendments on Soil Fungal Composition

“…Particularly, the higher oligotrophic population in CK and S-amended soils could be due to the lower nutrient availability, which in turn, enhanced the species richness in these treatments [35]. The destructive and beneficial impacts of fungal taxa later organic inputs have been widely reported [35][36][37][38]. It is likely that a higher availability of nutrients by M, MS, and S amendments may result in a shift of fungal taxa abundance that may be propitious or harmful to crop, human, and animals, thus influencing agroecosystem stability and performance.…”

Investigating the insecticidal potential of Geomyces (Myxotrichaceae: Helotiales) and Mortierella (Mortierellacea: Mortierellales) isolated from Antarctica

“…Whilst there is no history of Geomyces and Mortierella killing insects, species of Mortierella have been investigated as potential biological control agents against bacterial and oomycete plant pathogens (Tagawa et al 2010; Lambe and Wills 1983) and some Antarctic strains of M. alpina have been shown to exhibit anti-microbial activity (Melo et al 2013). …”

Microbial Communities in Potato Roots and Soil in Organic and Integrated Production Systems Compared by the Plate Culturing Method

“…64 74 1767** 2856** 37 834** 43 889** 13 800** 16 650** Statistically significant differences, according to chi-squared tests, between organic and integrated systems at *P = 0.05 and **P = 0.001. a Potential pathogens of potatoes (Douglas 1973;Amadioha 1998;Kirk 1991;Choiseul et al 2007;Peters et al 2008). b Potential antagonists of potato pathogens (Deshpande 1961;Aluko and Hering 1970;Nelson et al 1983;Van den Boogert and Jager 1984;Hoitink 1987;Jensen et al 2004;Soytong and Ratanacherdchai 2005;Lenc et al 2006;Mansoor et al 2007;Rivera-Varas et al 2007;Vero et al 2009;Tagawa et al 2010). greater in the integrated system only in 2006. Black scurf (R. solani) was more frequent in the integrated system, and common scab (S. scabies) in the organic system only in 2005.…”