Biocontrol agent Fusarium oxysporum f.sp. strigae has no adverse effect on indigenous total fungal communities and specific AMF taxa in contrasting maize rhizospheres.

Judith Zimmermann,Mary K Musyoki,Georg Cadisch,Frank Rasche

doi:10.1016/j.funeco.2016.05.007

Judith Zimmermann, Mary K Musyoki + Show 2 more

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https://doi.org/10.1016/j.funeco.2016.05.007

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Journal: Fungal Ecology	Publication Date: Jun 13, 2016
Citations: 17	License type: cc-by

Affiliation: University of Hohenheim

Abstract

We studied the effects of Fusarium oxysporum f.sp. strigae (Fos), a soil-borne biocontrol agent (BCA) against Striga hermonthica, on total fungal and arbuscular mycorrhizal fungal (AMF) taxa in rhizospheres of maize in both clayey and sandy soil. Effects of Fos-BCA ‘Foxy-2’ were evaluated against (1) S. hermonthica presence, and (2) organic fertilization with Tithonia diversifolia residues at 14, 28 and 42 d after ‘Foxy-2’ inoculation, via DNA-based quantitative PCR and TRFLP fingerprinting. In both soils, ‘Foxy-2’ occasionally promoted total fungal abundance, while the community composition was mainly altered by T. diversifolia and S. hermonthica. Notably, ‘Foxy-2’ stimulated AMF Gigaspora margarita abundance, while G. margarita was suppressed by S. hermonthica. Total fungal and AMF abundance were promoted by T. diversifolia residues. In conclusion, ‘Foxy-2’ resulted in no adverse effects on indigenous rhizosphere fungal communities substantiating its environmental safety as BCA against S. hermonthica.

Highlights

The parasitic weed Striga hermonthica is a major constraint to cereal production in Sub-Saharan Africa causing yield losses worth US$ 9 billion (Ejeta, 2007; Gibbon et al, 2007)
Addition of T. diversifolia residues (F þ T, FþSþT) promoted total fungal abundance in both soils at all sampling dates compared to treatment F (P < 0.001)
Our results indicated that the promoting effect of ‘Foxy-2’ compensated for the suppressive effect of S. hermonthica on arbuscular mycorrhizal fungal (AMF) G. margarita which obviously represented an additional benefit when implementing ‘Foxy-2’ as biocontrol agent (BCA)

Summary

Introduction

The parasitic weed Striga hermonthica is a major constraint to cereal production in Sub-Saharan Africa causing yield losses worth US$ 9 billion (Ejeta, 2007; Gibbon et al, 2007). S. hermonthica parasitizes staples such as millet (Pennisetum americanum), sorghum (Sorghum bicolor), maize (Zea mays), and rice (Oryza sativa) (Elzein and Kroschel, 2004; Marley et al, 2004). It infests more than 50 million hectares of farmland with intensifying dissemination in Sub-Saharan Africa, which makes it one of the gravest threats to food security in this region (Parker, 2012). Ndambi et al (2011) reported that ‘Foxy-2’ colonized endophytically the roots of the host crop (e.g., sorghum), where the biocontrol activity of ‘Foxy-2’ was initialized after S. hermonthica attacked the root system

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