Germinate-to-Exterminate: Pre-Crop Stimulation of Verticillium dahliae Microsclerotia Germination by Root Exudates as a Novel Strategy for Sustainable Control of Verticillium Wilt

Verticillium wilt (VW) is an important soil-borne disease caused by Verticillium species. VW has been reported in nearly 400 plant species from various families, including but not limited to Solanaceae, Brassicaceae, Cucurbitaceae, Fabaceae, Rosaceae, Caprifoliaceae, Malvaceae, Lamiaceae, and Sapindaceae. Potato (Solanum tuberosum L.), belonging to the Solanaceae family, is one of the most important staple crops globally and can be greatly impacted by VW, resulting in more than 40% yield losses in heavily infested commercial fields. VW in potatoes can be caused by infections with Verticillium dahliae (the most damaging species), V. albo-atrum, V. tricorpus, and others. V. dahliae produces microsclerotia (MS), resting structures that can persist in the soil for more than 10 years, even without a host crop, making effective field management challenging. Additionally, the incidence and severity of VW can be increased when root lesion nematodes and V. dahliae co-infect potato crops. Root exudate metabolites facilitate plant-microbial communication, which is also essential for the pathosystems adaptation to environmental change. These can also provide important signals to plant pathogens; for example, to facilitate stimulation of V. dahliae MS germination. A thorough understanding of how root exudates drive plant-pathogen interactions and how this knowledge can be applied to disease suppression will aid in the development of novel biomolecules to manage soil-borne fungal pathogens, thereby reducing or limiting the need for harmful pesticides. In this review article, we examine the current state of knowledge and identify gaps in our understanding of VW and its interactions with root exudates from host plants, highlighting a potential novel strategy for sustainable control of VW in potato crops, known as the germinate-to-exterminate (G2E) approach.