Endophytic fungi from Brachiaria grasses in Brazil and preliminary screening of Sclerotinia sclerotiorum antagonists

Danielly De Souza Gama,Patrícia Gomes Cardoso,Lucas Magalhães De Abreu,Flávio Henrique Vasconcelos De Medeiros,Ítalo Augusto Férrer Melo Santos,Whasley Ferreira Duarte

doi:10.1590/1678-992x-2018-0210

Danielly De Souza Gama, Patrícia Gomes Cardoso + Show 4 more

Open Access

https://doi.org/10.1590/1678-992x-2018-0210

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Abstract

ABSTRACT: Fungal endophytes of Brachiaria, a nonhost of Sclerotinia sclerotiorum, may harbor species with antagonistic effects against this plant pathogen. The objective of this work was to investigate the diversity of endophytic fungi associated with different Brachiaria species and hybrids and evaluate their potential to inhibit the plant pathogen S. sclerotiorum. Stem samples from 39 Brachiaria spp. plants were collected in pasture fields and experimental areas of three states of Brazil resulting in 74 endophytes isolated. Twenty-eight species were identified by sequences of the Internal Transcribed Spacer (ITS) and 18S rDNA regions. Paraconiothyrium sp. was the most abundant endophyte, accounting for 24 % (14 isolates) of total, and it was isolated from B. ruziziensis, B. decumbens, B. humidicola, and B. brizantha. Phoma sorghina was the second most abundant taxon, followed by Sarocladium strictum, and Plenodomus sp. In vitro analyses showed that Paraconiothyrium sp., Sarocladium kiliense, Acremonium curvulum, Setophoma terrestris, Dissoconium sp., and Cladosporium flabelliforme exhibited antagonistic activity against S. sclerotiorum, with percentages of growth inhibition ranging from 25 to 60 (p < 0.05). Paraconiothyrium sp. BBXE1 (60 %), BBPB4.1 (60 %), BCMT4.1 (54 %), and S. kiliense (54 %) showed the highest values of Antagonism Percentages (AP). Therefore, fungi with inhibitory activity against S. sclerotiorum such as Paraconiothyrium sp. are naturally endophytic in Brachiaria grasses.

Highlights

Grass pastures are widely distributed in different regions of Brazil, and the success of their establishment depends on the use of robust forage species
Stem samples from 39 Brachiaria spp. plants were collected in pasture fields and experimental areas of three states of Brazil resulting in 74 endophytes isolated
In vitro analyses showed that Paraconiothyrium sp., Sarocladium kiliense, Acremonium curvulum, Setophoma terrestris, Dissoconium sp., and Cladosporium flabelliforme exhibited antagonistic activity against S. sclerotiorum, with percentages of growth inhibition ranging from 25 to 60 (p < 0.05)

Summary

Introduction

Grass pastures are widely distributed in different regions of Brazil, and the success of their establishment depends on the use of robust forage species. The beneficial association of some agricultural grass species from temperate regions with vertically transmitted Clavicipitaceous fungal endophytes is a well stablished phenomenon (Saikkonen et al, 2006). This mutualism may protect plants against the growth of herbivore insects through the balance between antagonistic signaling pathways and increased availability of nutrients (Saikkonen et al, 2006, 2013). This type of symbiosis is not commonly observed in tropical grasses (Sánchez Márquez et al, 2012). A large diversity of horizontally transmitted endophytic fungi in Poaceae species used for cattle feeding in tropical regions deserves further investigation (Rodrigues and Dias-Filho, 1996)

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