Biological control of downy mildew Peronosclerospora spp. L. by application of endophytic agents in corn

This research was carried out to evaluate endophytic biocontrol agents (eBCA) in inducing corn plant resistance to downy mildew Peronosclerospora spp. In this context, the estimation of total phenolic content and peroxidase (POD) enzyme activity was carried out in contrast to control without induction treatments. Corn seed treatment using three eBCA II.D2.2, DC.5, and AC.3 on susceptible and tolerant cultivars in a screenhouse and field showed variation in downy mildew reduction. The results showed that Trichoderma asperellum AC.3 treatment suppressed downy mildew by 2.7–23.0% in the screen house. In the field, resistance induction by applications of Bacillus cereus II.D2.2, Fusarium verticillioides DC.5, and T. asperellum AC.3 suppressed the infection from 23% to 79% on susceptible cultivars. However, the T. asperellum AC.3 treatment reported the highest suppression of 55–79% on tolerant and susceptible cultivars. Resistant induction with F. verticillioides DC.5 increased POD enzyme activity by 300.5% and suppressed the infection by 63% in the field. The pathogen suppression ability through the induction with eBCA was related to triggering the increase of total phenolic content and POD enzyme activity in plant tissues. Applications of B. cereus II.D2.2, F. verticillioides DC.5, and T. asperellum AC.3 suppressed downy mildew infection in the field through the induction of total phenolic content and POD enzyme activity in corn. Meanwhile, the best treatment using T. asperellum AC.3 was lower by 30–70% than the application of synthetic fungicide as control.