Fluorescence Labeling Of Curvularia Lunata And Its Infection In Maize

Maize curvularia leaf spot, caused by Curvularia lunata (Wakker) Boed., is oneof the most important leaf diseases of popular in the north of china recently. Since itwas found in seaboard of Liaoning form the end of1970s to the beginning of1980s,it has spread out toward many regions, and caused great economic loss in maize.Although many studies have been focussed on breeding highly resistant varieties oron virulence differentiation and pathogenicity mechanisms of this fungus, relativelylittle is known at present about its detailed infection process.In this paper, fluorescent protein was delivered into C.lunata strains95-1viaAgrobacterium tumefaciens-mediated transformation (ATMT). The mutant, whichshowed the minimum differences Cl was selected by physio-biochemicalpathogenicity characteristics, was employed for the systemic infection of the fungusin leaves of the susceptible and resistance maize by the fluorescence microscope.Themain results as followed: the fluorescent protein DsRed and GFP were inserted in thegenome of C. lunata by ATMT randomly. The main results of physio-biochemicalpathogenicity characteristics anlaysis showed the C.lunata labelled with DsRedteaded to from the mutants.In compatible interaction, the conidia of C.lunata germinated at2h afterinoculation. The germination percentages of conidia examined at6h were90%. Itwas observed that one germ tube, occasionally along with two, development from agerminated spore. The germ tube grew rapidly, formed considerable branched andattachment structure. Invasive hypha penetrated epidermal cell through intercellularspace between24h and48h. Invasive hypha became thin when it penetrated cell wall.After intracellular mycelium formation, cell organelle were not found and cellsformed a cavity, later the entire cell collapsed and necrosised. On120h afterinoculation, conidiophore and conidia stretched form intercellular space, and cornleaves appeared typical symptomon. In incompatible interaction, hypha penetratedepidermal cell through intercellular space at48h after inoculation, Some of the cellsin the resistant lines died to inhibit the infection and growth of the pathogen; On96h after inoculation, corn generated spots was little.The method of RT-PCR was applied to analyze the changes of the related factorsafter defense in the resistant and susceptible inbred lines when infected by C. lunata.The results revealed that between12h and48h after infection by the pathogen, thetranscription levels of the defense-related genes, such as Phenylalanineammonia-lyase (PAL), Pathogenesis related protein (PR-1, PR-10) and so on wereenhanced significantly. Meanwhile, the expression time of the induced defense genesin the resistant lines was earlier than the susceptible lines, and the induced expressionlevel was higher in the resistant than the susceptible lines. The transcription levels ofthe resistant genes Lipoxygenase (LOX) related to the JA signal pathway had nochanges in both resistant and susceptible lines. Apoptosis in the resistant lines wasearlier, and was presumed defense reaction of resistant lines.441maize germplasm lines were evaluated for the resistance to C.lunata. A fewlines were highly resistant. The percentages of the highly resistant, resistant,moderately resistant, susceptible, and highly susceptible lines in the maize germplasmwere1.81%,12.01%,16.78%,55.34%and14.06%, respectively. The percentages ofresistance cultivars in the inbred lines was less than the landraces.