Seed application of Priestia megaterium strains reduces maize diseases caused by Fusarium graminearum and Phyllachora maydis

Tar spot, caused by Phyllachora maydis, and Fusarium rot, caused by Fusarium graminerum, are problematic diseases of corn, and new management strategies are needed. Two strains of Priestia megaterium, isolated from nongerminating tar spot stromata, could serve as biocontrol agents. In laboratory studies, mean lesion size caused by F. graminearum on leaves of maize inbred N6 was significantly reduced by 28.6% and 38.7% compared to controls when either P. megaterium strain 10 or P. megaterium strain 11 were applied to germinated seed, respectively. The overall incidence of tar spot disease caused by P. maydis on leaves was reduced by 41.6% and 53.9%, respectively, when P. megaterium strain 10 and strain 11 were applied to seeds of maize inbred GE440 in the first year. The incidence of lower leaves with greater than 20 tar spots was significantly reduced by 41.9% and 72.3%, respectively, when P. megaterium strain 10 and strain 11 were applied in the second year. Additional experiments determined that neither bacterium strain caused damage to sheep red blood cells or corn leaves.

由玉米斑枯病菌（Phyllachora maydis）引发的玉米斑枯病（Tar spot），以及由禾谷镰孢菌（Fusarium graminerum）引发的玉米赤霉腐病，均为危害性较强的玉米病害，亟需研发新型防控策略。本研究中分离自未萌发玉米斑枯病子座的两株巨大普雷斯特氏杆菌（Priestia megaterium），可作为潜在生防菌剂。实验室研究结果表明：将菌株10或菌株11分别施用于萌发种子后，禾谷镰孢菌在玉米自交系N6叶片上引发的平均病斑面积较对照组分别显著降低28.6%与38.7%。在第一年试验中，将菌株10与菌株11分别施用于玉米自交系GE440种子后，玉米斑枯病菌引发的叶片总发病率分别降低41.6%与53.9%；第二年试验中，下部叶片上斑点数量超过20个的病株率分别显著降低41.9%与72.3%。额外开展的验证试验证实，两株菌株均不会对绵羊红细胞或玉米叶片造成损伤。