Interspecies crosstalk between Magnaporthiopsis maydis and Fusarium verticillioides in mutually infected maize plants

Maize late wilt disease (LWD), caused by the fungus Magnaporthiopsis maydis, affects crops in Israel, Egypt, Spain, Portugal, India, and other countries. This study examines the interaction between M. maydis and Fusarium verticillioides, another post-flowering stalk rot pathogen. A confrontation assay revealed antagonism between the species. Fusarium verticillioides extrolites significantly hindered M. maydis in cross-cultivation. In a 40-day growth room test, introducing F. verticillioides at sowing and M. maydis one week later reduced plant growth to 44% of the control. Vice versa or simultaneous inoculation also stunted growth significantly (55% and 67%, respectively). Real-time PCR confirmed these growth responses by tracking both pathogens' DNA in plant roots. Similar trends were observed in a semi-field, full-season potted trial. Magnaporthiopsis maydis showed higher aggressiveness with a 40% plant survival rate compared to the minor influence of F. verticillioides. At harvest, M. maydis DNA levels were up to 1000-fold higher than F. verticillioides. Co-inoculation during seeding improved healthy plant rates from 10% (M. maydis alone) to 30%. Pre-infection with F. verticillioides followed by M. maydis resulted in 80% asymptomatic plants at harvest and significantly decreased M. maydis infection, though plant growth indices (particularly the yield) remained low. This study highlights the interactions between these pathogens, potentially limiting LWD damage.