Effect of Selected Trichoderma Strains and Metabolites on Olive Drupes

Irene Dini,Roberta Marra,Alessia Staropoli,Francesco Vinale,Marica Pascale

doi:10.3390/app11188710

Abstract

Beneficial fungal strains of the genus Trichoderma are used as biofungicides and plant growth promoters. Trichoderma strains promote the activation of plant defense mechanisms of action, including the production of phenolic metabolites. In this work, we analyzed the effects of selected Trichoderma strains (T. asperellum KV906, T. virens GV41, and T. harzianum strains TH1, M10, and T22) and their metabolites (harzianic acid and 6-pentyl-α-pyrone) on drupes of young olive trees (4-year-old) cv. Carolea. This study used the untargeted analysis of drupe metabolome, carried out by LC–MS Q-TOF, to evaluate the phenolics profiles and target metabolomics approach to detect oleuropein and luteolin. The untargeted approach showed significant differences in the number and type of phenolic compounds in olive drupes after Trichoderma applications (by root dipping and drench soil irrigation method) compared to control. The levels of oleuropein (secoiridoid) and luteolin (flavonoid) varied according to the strain or metabolite applied, and in some cases, were less abundant in treated plants than in the control. In general, flavonoids’ levels were influenced more than secoiridoid production. The dissimilar aptitudes of the biological treatments could depend on the selective competence to cooperate with the enzymes involved in producing the secondary metabolites to defend plants by environmental stresses. Our results suggest that using selected fungi of the genus Trichoderma and their metabolites could contribute to selecting the nutraceutical properties of the olive drupe. The use of the metabolites would bring further advantages linked to the dosage in culture and storage.

Highlights

Since ancient times olive trees (Olea europaea L.) have been cultivated throughout the Mediterranean area for their fruits and oil production
They consist of phenolic alcohols, phenolic acids, flavones, lignans, and secoiridoids [12] responsible for Extravirgin olive oil (EVOO) bitterness, pungency, fragrance, and antioxidative properties [13]
Carolea) influence the weight of the drupes and the composition of phenolic compounds they contain, in different ways depending on the strain or metabolite applied

Summary

Introduction

Since ancient times olive trees (Olea europaea L.) have been cultivated throughout the Mediterranean area for their fruits and oil production. EVOO is present in all variants of the Mediterranean diet The latter is a healthy diet adopted by the Italian and Greek population in the 1960s [7], reducing the risk of cardiovascular disease, cancer, type 2 diabetes, and cognitive disorders [8]. Fungi belonging to the genus Trichoderma are commonly used in agriculture as biocontrol agents (they inhibit soils and air diseases) and plant growth promoters [35,36] They enhance the abiotic stress tolerance (e.g., salinity, drought), yields production, nutritional uptake, leaf area, root system growth, and activate protective mechanisms against oxidative injury [37,38]. Hypoglycemia, hypotension, and hypocholesterolemia and prevent angiogenesis, inflammation [44], and cancer [45]

Methods

Discussion

Conclusion