Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2002
Publication Date: N/A
Interpretive Summary: The fungus Fusarium graminearum is pathogenic to wheat and other cereals. This fungus attacks both the young seedling plants and seeds on matured plants where mycotoxins are produced that render developing grain unsuitable for commercial use. The seedling aspect of this disease is referred to as seedling blight while the disease of the seed is referred to as wheat scab. The economic loss of both disease is tremendous, especially since this fungus is highly infectious throughout the wheat growing season. This fungus is difficult to control resulting in millions of dollars of damage to the wheat industry. We discovered and patented a species of bacterium that has potential as a biological control of this fungus since it is antagonistic to fungi and enhances plant growth. The bacterium, Bacillus mojavensis, is unique because it grows inside plants from its initial application to seed. We studied under greenhouse conditions the ability of this endophytic bacterium to prevent seedling blight disease in eight varieties of wheat with differing tolerance rating to F. graminearum. The results of this study established that under greenhouse and growth room conditions the bacterium reduces both seedling blight and increases plant vigor, which suggests that this bacterium will control the infection and pathogenicity from F. graminearum in wheat when grown under field conditions.
Technical Abstract: Fusarium species infect grains and cereals causing billions of dollars in losses to the agricultural markets. F. graminearum - infected grain decreases seed germination and seedling emergence, causes post-emergence seedling death, Fusarium head blight, and reduces yield. The fungus also produces the mycotoxins, deoxynivalenol and zearalenone. Current seed treatments are effective against surface fungi on grains but have limited effects on the control of systemic persistent fungal infection that can produce seedling blight and scab. A patented endophytic bacterium, Bacillus mojavensis, a species within the B. subtilis subgroups, was studied to determine its potential as an endophytic biocontrol for F. graminearum which produces seedling blight of wheat and mycotoxins. The protection of eight commercial varieties of hard red spring and soft red winter wheat by this bacterium under growth room and greenhouse tests for control of seedling blight, and the overall effects of the bacterium on plant growth were determined. This bacterium was antagonistic in vitro to numerous fungi including F. graminearum. Data from plant growth room and greenhouse studies indicated that B. mojavensis inoculated kernels kernels reduced endophytic seedling colonization and seedling blight disease from F. graminearum, and increased the number of germinating seeds, rate of seed germination, and seedling root and shoot growth in the eight wheat varieties tested, including the highly susceptible variety, Norm. The results established that this endophytic bacterium has strong potentials for reducing seedling blight in major wheat cultivars.