Health-Promoting Properties of Plant Products: The Role of Mycorrhizal Fungi and Associated Bacteria

Monica Agnolucci,Alessandra Turrini,Luciano Avio,Cristiana Sbrana,Michela Palla,Manuela Giovannetti

doi:10.3390/agronomy10121864

Abstract

The concept of food quality, traditionally based on nutritional and sensory properties, has recently acquired an additional meaning, referring to the health-promoting properties of plant products, that are ascribed to plant secondary metabolites called phytochemicals, primarily represented by polyphenolic compounds and glucosinolates. The diversity and content of phytochemicals in plant products are affected by different variables, such as plant genotype, agronomic factors, and arbuscular mycorrhizal fungi (AMF), which establish mycorrhizal symbioses with most crops, including cereals, legumes, vegetables, fruit trees, sunflower, cotton, and sugarcane. AMF and associated bacteria enhance plant growth and health, and affect the production of polyphenols and carotenoids, and the activity of antioxidant enzymes. The production of health-promoting phytochemicals was shown to be differentially modulated by different AMF isolates and bacterial strains, in several food plants, i.e., tomato, lettuce, strawberry, artichoke, maize, grapevine, sunflower. Here, we provide an overview of recent studies concerning the multiple roles played by AMF and associated bacteria in the modulation of the biosynthesis of plant secondary metabolites with health-promoting activity, and discuss the development of designed multifunctional consortia to be used in sustainable agriculture.

Highlights

The quality of plant products and their derived foods and ingredients represent the main aim to be pursued by sustainable agriculture, in the best interest of farmers, consumers, and producing countries
Fruits, vegetables, legumes, grains, nuts, and seeds are currently valued for size, weight, external appearance, taste, and nutritional content, and for their nutraceutical properties, i.e., their ability to promote human health by preventing diseases and decreasing the risk of mortality from cancer [1,2,3]. Such bioactive properties are mainly ascribed to plant secondary metabolites, called phytochemicals, that show antioxidant, antibacterial, and antiviral activities and the ability to protect against chronic diseases, encompassing cardiovascular diseases (CVD), certain cancers, neurodegenerative diseases, and to Agronomy 2020, 10, 1864; doi:10.3390/agronomy10121864
Phytochemicals are primarily represented by polyphenolic compounds, such as flavonoids, consisting of more than 5000 bioactive compounds reportedly active in the reduction of CVD risk and in chemoprotection, and by glucosinolates, encompassing about 130 molecules mainly found in Brassicaceae, plants considered as food protection agents, given the positive correlation between their consumption and cancer risk reduction [9,10,11,12,13,14]

Summary

Introduction

The quality of plant products and their derived foods and ingredients represent the main aim to be pursued by sustainable agriculture, in the best interest of farmers, consumers, and producing countries. Fruits, vegetables, legumes, grains, nuts, and seeds are currently valued for size, weight, external appearance, taste, and nutritional content, and for their nutraceutical properties, i.e., their ability to promote human health by preventing diseases and decreasing the risk of mortality from cancer [1,2,3] Such bioactive properties are mainly ascribed to plant secondary metabolites, called phytochemicals, that show antioxidant, antibacterial, and antiviral activities and the ability to protect against chronic diseases, encompassing cardiovascular diseases (CVD), certain cancers, neurodegenerative diseases, and to Agronomy 2020, 10, 1864; doi:10.3390/agronomy10121864 www.mdpi.com/journal/agronomy. The analyses showed a large TAC variability, expressed as μmol of Trolox equivalents (TE)/g among different species of fruits-from 13.4 in apricots to 94.6 in cranberries-and among varieties of the same species-from 26.7 in Golden Delicious to 42.7 in Red Delicious apples [15] Such results stimulated researches and breeding programs aimed at selecting crops with enhanced concentrations of beneficial plant secondary metabolites. We discuss the best research strategies for their utilization in sustainable agriculture for the production of plant foods with high nutritional and nutraceutical value (Figure 1)

Arbuscular Mycorrhizal Fungi and Associated Bacteria

The Production of Beneficial Phytochemicals as Affected by AMF

Findings

Conclusions and Perspectives for Future Studies