Serendipita Species Trigger Cultivar-Specific Responses to Fusarium Wilt in Tomato

Abstract

The endophytic fungi <i>Serendipita indica</i> and <i>S. vermifera</i> have recently gained increasing attention due to their beneficial effects on plant growth and plant health. Little is known about other species, such as <i>S. williamsii</i> and <i>S. herbamans</i>. To test their biocontrol and growth-promoting potential, susceptible and tolerant tomato cultivars (Kremser Perle and Micro-Tom, respectively) were inoculated with <i>S. williamsii, S. herbamans, S. indica</i>, or <i>S. vermifera</i> and challenged with the soilborne pathogen <i>Fusarium oxysporum</i> f. sp. <i>lycopersici</i> (<i>Fol</i>) in greenhouse experiments. Furthermore, in vitro assays on the direct inhibitory effects of <i>Serendipita</i> spp. against <i>Fol</i> were performed. Negative effects of <i>Fol</i> on phenological growth in the susceptible cultivar were alleviated by all four applied <i>Serendipita</i> spp. Apart from these similar effects on biometric parameters, disease incidence was only reduced by <i>S. herbamans</i> and <i>S. vermifera</i>. In the tolerant cultivar, disease parameters remained unaffected although shoot dry mass was negatively affected by <i>S. vermifera</i>. Direct effects of <i>Serendipita</i> spp. against <i>Fol</i> were not evident in the in vitro assays indicating an indirect effect via the host plant. Our results highlight the importance of identifying cultivar-specific effects in pathogen-endophyte-plant interactions to determine the most beneficial combinations.