The role of Plant Growth Promoting (PGP) bacteria in the growth of Mediterranean diet plants producing high-value compounds

Abstract

Loss of fertility, together with drought and aridity, results in soil unproductivity and eventually desertification. Unsustainable agricultural practices are currently stressing the soil: an undervalued resource that, in addition to food, provides a multitude of invaluable services such as regulating the microclimate, reducing contaminants, and capturing CO2. Hence, there is an increasing need to resort to sustainable approaches toward agricultural systems. Although Sicily is one of those regions most affected by water shortages, it is at the same time a reservoir of drought-resistant Mediterranean plants with high nutritional value and a rich microbiota. This project aims to promote agriculture based on Plant Growth Promoting Rhizobacteria (PGPR) [1] in order to reduce soil stresses. These microbes exert beneficial effects on plants that can be classified into direct such as nutrient solubilization and production of plant hormones (auxins, cytokinins, gibberellins), and indirect such as protection against pathogenic microorganisms [2]. Therefore, in the not-too-distant future, they could be used on a large scale in agricultural soils. Beyond the cited growth-promoting activity, is still unknown their role in increasing the production of bioactive molecules in plants: some of the best-known belong to the class of flavonoids, pigments, and terpenoids [3]. Within this context, benefits obtained from the interaction of these bioactive molecules would enhance a multitude of both physiological and epigenomic effects on the human body and would be provided by all-natural resources [4]. In a context where the concern for human health is primary over all other needs, the use of fruit extracts or concentrated oils rich in bioactive substances would contribute to an improved quality of life, using these products in both nutritional and agricultural fields. The innovative potential of using microorganisms in the agri-food system would lead to the mitigation of the use of plant stimulants, antibiotics, and chemical pesticides. Therefore, a focus will be made on the rhizosphere of all those plants capable of returning a high content of these compounds.