The Physiological And Molecular Mechanism Of Corn Against Fusarium Proliferatum Infection

In recent years, a new disease which was similar to maize sheath blight, corn brown spot and bacterial diseases has been widespreaded in corn-planting regions of China. The new disease was named corn sheath rot according to it mainly occurred on the leaf sheath of maize. The resistance mechanism of maize against corn sheath rot was not reported at home and abroad. In this study, the popularized maize varieties in North and Northeast China were selected as experimental materials. The disease-induced fungus, Fusarium proliferatum was inoculated on the plants of different maize varieties planted in the field, the varieties with different resistance ability to the disease were selected, and the physiological and biochemical changes and resistance gene expression were determined, so that the physiological and molecular mechanism of maize against to corn sheath rot was clarified. The main results were summarized as follows:1. The popularized maize varieties in North and Northeast China had good resistance to corn sheath rot. Most of the varieties showed high resistance or middle resistance to the disease, and no susceptible one was found.2. The symptoms of the disease in field were different for different maize varieties. The lesion on the variety Zhengdan958 was larger, irregular shape and dark brown. The lesion on the variety Xundan20 was smaller, with a black center and water stains-like edge. For the variety Zheng58, the lesion was larger, with a yellow-brown or black center and dark brown edge. For the variety 9058, the lesion was medium size, irregular shape and black color. On the varieties Chang7-2 and Xun92-8, the lesions showed smaller, yellow water stain-like.3. For varieties with different resistance to the disease, the enzyme activities in leaf sheath were gradually increased after inoculated with F. proliferatum and reached the maximum values, thereafter decreased. But the maximum enzyme activities of resistant varieties were higher, earlier and maintained for a long time. 4. The lignin contents in leaf sheath of all varieties with different resistance to the disease were gradually increased after inoculated with F. proliferatum. But the lignin contents in resistant varieties were higher than those in middle resistant ones pre- and post-inoculation.5. Before inoculated with F. proliferatum, the contents of total sugar and reducing sugar in leaf sheath of resistant varieties were higher than those of middle resistant ones. After inoculation, the contents of the sugars of all varieties with different resistance were gradually decreased. The sucrose contents of middle resistant varieties were increased after inoculated, but were still lower than those of resistant ones.6. The resistance gene expression levels of all varieties with different resistance gradually increased after inoculated, but those in resistant varieties were significantly higher than in middle resistant ones.