Identification Of The Pathogen Of Corn Sheath Rot And Pathogenic Mechanism Research

In this study, we collected corn sheath rot pathogen standard samples from 38 regions in 8 provinces, in order to clear genetic relationship of the strains, we identified them by morphological and molecular methods; we studied the interaction between the pathogen of corn sheath rot. The results can be showed as follows:1. The symptoms of sheath rot of corn in the fields can be divided into 4 types: A : a central brown, dark brown edge, irregular shape spot; B: a big dark brown and irregular shape spot; C: Red brown spot, it is an oval or round red brown spot at first, then the number of spots merged into irregular red-brown spot with a unclear edge; D: water-soaked spot. The pathogen can be identified as Fusarium proliferatum by conventional phytopathology and molecular methods.2. 50 isolates from different areas in China in 2009 were analyzed by detecting the conservation of the internal transcribed spacer regions of the ribosomal gene, The ITS phylogenetic trees were generated with the software of Mega 4. The results showed that isolates could be divided into two groups by NJ tree and ME tree analysis and each group included strains in different regions. This indicates that no significant differences in the pathogen from different areas.3. The coarse toxin of Fusarium has strong toxic effects on corn stem and leaf sheath. However, the toxin can not cause serious disease on the maize grain.4. 5 Extracellular wall degrading enzymes(PG, CX, PMG, PGTE and PMTE) could be produced by Fusarium graminearum, Fusarium moniliforme and Fusarium proliferatum in a modified Marcus medium, the activities of the Extracellular wall degrading enzymes produced by Fusarium proliferatum are higher than Fusarium graminearum and Fusarium moniliforme. the activities of PG, CX, and PMG produced by these Fusariums are much higher than the ones of PGTE and PMTE.5. By determinating plant's total content of the sugar and the activities of the PAL, POD and SOD, leaf sheaths were inoculated with the pathogen. It is found that the incidence of plants is inversely proportional to the total content of the sugar and the activities of PAL, POD and SOD.