Biological control of Fusarium oxysporum f. sp. ciceri and Ascochyta rabiei infecting protected geographical indication Fuentesaúco-Chickpea by Trichoderma species

Abstract

The Protected Geographical Indication Fuentesaúco-Chickpea (F-C) is a legume crop that was developed in the south of the province of Zamora (Spain). It has great agronomic, economic, and cultural importance worldwide. Its cultivation is threatened mainly by the fungal diseases Fusarium wilt (causal agent Fusarium oxysporum f. sp. ciceri) and Ascochyta blight (causal agent Ascochyta rabiei). By conducting an in vitro antagonism study, we determined that strains belonging to the species Trichoderma atroviride, T. hamatum, T. harzianum, and T. koningii are the most effective against both pathogens. The mechanisms of action of these strains are as follows: mycoparasitism, antibiosis, and competition for space and/or nutrients. Subsequently, these four Trichoderma spp. strains were used for an infection test in F-C plants to test their activity against both fungal pathogens by plant root inoculation. We reported that T. atroviride and T. koningii were capable of controlling F. oxysporum f. sp. ciceri in F-C plants directly, and T. koningii activated the production of salicylic acid as a plant defense response. In the case of A. rabiei foliar infection, plant roots inoculated with T. hazianum and T. koningii species were able to significantly decrease the occurrence of disease through systemic activation of jasmonic acid as a defense response. Regarding the effects of the Trichoderma species on F-C productivity, the species T. hamatum and T. koningii were able to significantly increase (by 50% and 100%, respectively) the formation of grains per plant. Therefore, we propose that T. koningii could be used to control F. oxysporum f. sp. ciceri and A. rabiei in F-C plants under greenhouse conditions through direct mechanisms as well as the induction of local and systemic defense responses and thereby promoting crop productivity.