Chapter 8 - Applications of Verticillium spp. for inducing secondary metabolism in plants to cope with biotic and abiotic stress

Abstract

Farmers face significant challenges in achieving sustainable agriculture that meets the growing global population's high demand for food. The overutilization of pesticides has had severe effects on biodiversity due to their poisoning and residual effects, leading to the resistance of several pests. Hence, a greater awareness of synthetic chemicals has resulted in the search for natural and eco-friendly fertilizers, herbicides, and pesticides with adequate cost and efficiency. In this context, entomopathogenic fungi are considered a novel alternative for synthetic pesticides since they produce bioactive compounds that trigger plant defense mechanisms or induce the synthesis of secondary metabolites in the host plants. The entomopathogenic fungus from the genus Verticillium produces several metabolites with agricultural potential as biostimulants; however, their roles in pathogenicity and other relations with their hosts and challenging microbes are not well understood. Fungi infections are biotic stresses that reduce yield by causing severe crop damage or plant death. Verticillium spp. is an entomopathogenic fungal species with endophytic characteristics that lead to several symptoms. In susceptible plants, leaf flaccidity (wilting), chlorosis, and necrosis are common symptoms. However, tolerant plants present no symptoms and are more resilient. Tolerance to Verticillium may include compensatory benefits like increased leaf size, accelerated bud break, delayed senescence of infected tissue, increased nutrient absorption, cross-protection against herbivory or other virulent diseases, and induction of bioactive compounds in host plants. Although there is little information on fungi elicitation in plants, some studies have aimed to induce plant resistance to avoid disease symptoms that affect crop yield. The present chapter reviews the potential implementation of Verticillium spp. as a biostimulant and its application against abiotic and biotic stress in plants, as the bioactive compounds produced by the fungus or the host plants confer resistance to stressful conditions.