In vitro Characterization of Chrysovirus-1-Induced Hypovirulence of Bipolaris maydis

Abstract

Mycoviruses are viruses that infect fungi. Chrysovirus-1 has been reported as a mycovirus in Bipolaris maydis, which is the plant fungal pathogen for maize, and its infection results in the reduction of crop yield. We aimed to characterize Chrysovirus-1-infected B. maydis in terms of macroscopic morphology, transmission electron microscopy, colony size, biofilm formation, and stress responses focusing on osmotic stress (NaCl), oxidative stress (H2O2), thermotolerance (at 25, 37, and 45 °C), pH (5, 7, and 10), and metal stress (ZnSO4) in comparison with an uninfected strain. Our results demonstrated the presence of viral-like particles under TEM. The colony morphology of the infected strain displayed slight differences as significant delay in colony growth of the Chrysovirus-1-infected strain when compared to the uninfected strain. Moreover, biofilm mass of the infected strain was examined as being lower than that of the uninfected strain. Several stress response tests also demonstrated that the infected strain exhibited higher sensitivity to all stress responses compared to the uninfected strain. Thus, our results suggested that mycoviruses as demonstrated in this study (Chrysovirus-1) can induce the hypovirulence phenomenon in the pathogenic fungi (B. maydis).