SOIL FUNGISTASIS AGAINST FUSARIUM GRAMINEARUM UNDER DIFFERENT CROP MANAGEMENT SYSTEMS

Bruno Brito Lisboa,Anelise Beneduzi,Adriana Ambrosini,Cimélio Bayer,Luciane Maria Pereira Passaglia,Luciano Kayser Vargas,Flávio Anastácio De Oliveira Camargo

doi:10.1590/01000683rbcs20150683

Abstract

Soil management, in terms of tillage and cropping systems, strongly influences the biological properties of soil involved in the suppression of plant diseases. Fungistasis mediated by soil microbiota is an important component of disease-suppressive soils. We evaluated the influence of different management systems on fungistasis against Fusarium graminearum, the relationship of fungistasis to the bacterial profile of the soil, and the possible mechanisms involved in this process. Samples were taken from a long-term experiment set up in a Paleudult soil under conventional tillage or no-tillage management and three cropping systems: black oat (Avena strigose L.) + vetch (Vicia sativa L.)/maize (Zea mays L.) + cowpea (Vigna sinensis L.), black oat/maize, and vetch/maize. Soil fungistasis was evaluated in terms of reduction of radial growth of F. graminearum, and bacterial diversity was assessed using ribosomal intergenic spacer analysis (RISA). A total of 120 bacterial isolates were obtained and evaluated for antibiosis, and production of volatile compounds and siderophores. No-tillage soil samples showed the highest level of F. graminearum fungistasis by sharply reducing the development of this pathogen. Of the cropping systems tested, the vetch + black oat/maize + cowpea system showed the highest fungistasis and the oat/maize system showed the lowest. The management system also affected the genetic profile of the bacteria isolated, with the systems from fungistatic soils showing greater similarity. Although there was no clear relationship between soil management and the characteristics of the bacterial isolates, we may conclude that antibiosis and the production of siderophores were the main mechanisms accounting for fungistasis.

Highlights

Soil-borne plant diseases cause significant crop damage, principally by attacking the root system of seedlings and adult plants
We evaluated the influence of different management systems on fungistasis against Fusarium graminearum, the relationship of fungistasis to the bacterial profile of the soil, and the possible mechanisms involved in this process
The study described in this paper evaluated fungistasis in a soil under different management systems designed to affect Fusarium graminearum, and explored the relationship of this phytopathogen with the genetic profile of the bacterial community of the soil and the probable microbiological mechanisms involved in fungistasis

Summary

Introduction

Soil-borne plant diseases cause significant crop damage, principally by attacking the root system of seedlings and adult plants. Reduction in the incidence of disease due to soil suppression is attributable to several factors, including induction of plant systemic resistance and direct inhibition of pathogens by the overall microbial activity of a soil (Weller et al, 2002). In this context, fungistasis can be defined in terms of soil suppression as the capacity of a soil to inhibit the germination of fungal spores and reduce the vegetative growth of phytopathogenic fungi (Garbeva et al, 2011). Fungistasis occurs through a variety of mechanisms linked to the microbial community of a soil, such as the production of antimicrobial compounds and competition for nutrients, especially Fe uptake mediated by siderophores (Hadar and Papadopoulou, 2012)

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Results

Conclusion