New Antifungal Compound, 6-Pentyl-α-Pyrone, against the Maize Late Wilt Pathogen, Magnaporthiopsis maydis

Abstract

6-pentyl-α-pyrone (6-PP) is a powerful Magnaporthiopsis maydis antifungal compound, recently discovered when the potent growth medium of Trichoderma asperellum was analyzed. Despite its high potential in plate assay, it was not inspected for plant treatment prevention. Late wilt disease, caused by the fungus M. maydis, threatens commercial maize production in high-risk areas. Thus, the search for control options against the pathogen is one of the top priorities in Israel, Egypt, and other countries. Disease-resistant maize genotypes can reduce the damages. Yet, aggressive variants of the fungus can overcome host resistance. The current study aimed at inspecting T. asperellum and its secreted metabolite, pure 6-PP, against the pathogen in plants over a full growth period. First, adding T. asperellum directly to seeds with sowing provides significant protection to sprouts (up to 42 days) in a growth room, with more than two-fold growth promotion and reduced pathogen root infection (detected by real-time PCR). The same procedure applied in a commercial field was less beneficial in rescuing the plants’ growth and yield. Still, it reduced the cobs’ symptoms by 11% and resulted in nine-fold lower levels of the pathogen’s DNA in the stem tissue. Second, the T. asperellum purified 6-PP compound (30 µg/seed) was used in seed coating and tested against the T. asperellum secretory metabolites’ crude (diluted to 50%). At the season’s end, these treatments improved plant biomass by 90–120% and cob weight by 60%. Moreover, the treatments significantly (p < 0.05) reduced the symptoms (up to 20%) and pathogen infection (94–98%). The current study’s results reveal the potential of 6-PP as a new fungicide against M. maydis. Such a treatment may protect maize plants from other soil diseases.