Fluorescence Labelling Of Fusarium Verticillioides And Its Application In Study Of Host-Fungus Interaction

Maize stalk rot occures widely all over the world. In recent years, this disease was ingravescent in China due to the shift of farming system (e.g., protective farming and straw returning) and weather conditions. Fusarium verticillioides (Sacc.) Nirenberg, one of the major pathogens of stalk rot in maize (Zea mays L.), is able to infect maize root, stalk, and ear, inciting seedling blight, stalk rot, and ear rot. It also can grow inside maize tissues like asymptomatic endophyte.In this study, gene DsRed encoding red fluorescent protein was delivered into F. verticillioides strain FV via Agrobacterium tumefaciens-mediated transformation (ATMT). the mutant, which showed the minimum differences with FV was selected by physio-biochemical characteristics analysis, was employed for further study. The main results as followed: fluorescent protein GFP and DsRed were inserted in the genome of F. verticillioidies by ATMT randomly. The results of physio-biochemical characteristics analysis showed the F. verticillioidies labelled with DsRed tended to form mutants. In this study, gene DsRed encoding red fluorescent protein was delivered into F. verticillioides strain FV via Agrobacterium tumefaciens-mediated transformation. Using the DsRed-tagged F. verticillioides, systemic colonization of the fungus in roots and stems of the susceptible and resistance maize inbred were investigated.In susceptible maize lines,the fungus invaded and multiplied inside the hair root tissues at the very beginning, and the fungus were able to colonize in hair roots without killing them. Then the hyphae of Fusarium verticillioidies expanded upward along the main roots. Some conidia adhered to the veins of root surfaces and germinated to produce hyphae, which expanded upward. The hyphae were able to expand along the intercellular space or ran across several cells by breaking into them. Fusarium verticillioidies was able to form the mosaic pattens, when they was propagated in susceptable maize roots, and the cells seems to be killed when they fill with hyphea. The hyphea alway located under maize root surface with some hair roots grew on it. The resistent maize lines, which developed less hair roots than susceptable maize lines, usually form the necrotispot to limit the expension of Fusarium verticillioidies. Analysis of colony forming unit (CFU) from diseased plants demonstrated that following inoculation the CFU values from roots tended to decrease, but those from stems inclined to increase. This indicates that F. verticillioides is able to attack the aboveground parts of plant via systemic colonization on roots.