Selection of Endophytic Beauveria bassiana as a Dual Biocontrol Agent of Tomato Pathogens and Pests.

Martina Sinno,Ilaria Di Lelio,Sheridan Lois Woo,Marta Ranesi,Maria Cristina Digilio,Vili Harizanova,Francesco Pennacchio,Donata Molisso,Eleonora Barra,Matteo Lorito,Stefania Vitale,Giuseppina Iacomino,David Turrà,Andrea Becchimanzi

doi:10.3390/pathogens10101242

Abstract

Endophytic fungi (EF) can enhance both plant growth and defense barriers against pests and pathogens, contributing to the reduction of chemical pesticides and fertilizers use in agriculture. Beauveria bassiana is an entomopathogenic fungus showing endophytism in several crops, often associated with a good capacity to limit the development of pests and disease agents. However, the diversity of the protective efficacy and plant response to different strains can be remarkable and needs to be carefully assessed for the successful and predictable use of these beneficial microorganisms. This study aims to select B. bassiana strains able to colonize tomato plants as endophytes as well as to control two important disease agents, Botrytis cinerea and Alternaria alternata, and the pest aphid, Macrosiphum euphorbiae. Nine wild-type isolates and one commercial strain were screened for endophytism, then further characterized for plant-growth promotion plus inhibition of disease development and pest infestation. Four isolates proved to have a good control activity against the biotic stressors tested, but only Bb716 was also able to promote plant growth. This work provides a simple workflow for the selection of beneficial EF, paving the way towards more effective use of B. bassiana in Integrate Pest Management (IPM) of tomato.

Highlights

Feeding the growing world population while decreasing the environmental impact of agriculture is one of the biggest challenges of our time that must be confronted in the present and future [1,2,3]
B. bassiana is a valuable, prospective biocontrol agent against both insect pests or fungal pathogens of tomato and a potential plant biostimulant. This paves the way for the development of a crop-improvement strategy with a single beneficial microorganisms (BMs) application that offers multiple beneficial effects to the plant
The screening process that was developed showed that the biocontrol efficiency and plant response to different strains can be remarkably diverse; a solid workflow procedure for strain selection is highly necessary to carefully chose the most promising plant BM

Summary

Introduction

Feeding the growing world population while decreasing the environmental impact of agriculture is one of the biggest challenges of our time that must be confronted in the present and future [1,2,3]. The most relevant plant-benefit effects demonstrated by BMs are the control and induced resistance to pest and pathogen attack, increased tolerance to abiotic stress, improved plant nutrition, plus growth promotion [7,8,9,10,11] In this context, increased attention has been given to the role of fungal endophytes for crop protection, to control the causal agents of disease and infestation, as well as enhance plant fitness [12,13,14,15], and increase above- and/or below-ground biomass associated to improved productivity and yield [12,16,17]. Many fungal endophytes are known to secrete a plethora of bioactive compounds that largely underlie the positive effects to the plant, which can have a direct antimicrobial or insecticidal effect and/or act indirectly to stimulate the plant defense response or growth [12,19,20,21]

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