Study On The Relation Between The Different Resistance To MRDV Of Different Maize Varieties And The Physiology And Biochemistry

We have researched the happen and influence of maize rough dwarf disease, the molecule biology identification of vims and identified many maize cultivars resistance to MRDV. Basing on the disease resistance identification of two years, we studied three cultivars which have different resistance to MRDV about the change of Peroxidase (POD), Polyphenol oxidase (PPO) Esterase ( EST), Superoxide dismutase (SOD) Phenylalanine ammonialyase (PAL) and Soluble protein (SPR) at three-leaf stagc and five-leaf stage. We also studied the change between the disease and healthy leaves at heading stage.Results show that, the activity of POD PPO and PAL in susceptible variety is higher than that of resistant variety at each stage. From this study, we can deduce that the activity of these enzymes is related to maize cullivars" susceptibility. After infected by virus, the enzyme activity of each variety increases, and the resistant variety changes the most; SOD activity of resistant variety is higher than that of susceptible variety. After infected, the activity goes down, and the frequency of the resistant variety is biggest too; The SPR content of susceptible variety is higher than others', which also shows the relation to susceptibility, but at three-leaf stage, the result is reversal and induces that the relation between the SPA and the resistance of variety have some relationship to maize growth duration. The infection of MRDV can diminish the content of SPR.At the heading stage, a POD isozyme band (Rf 0.261) appears in resistant variety, which is not happened in resistant variety. We speculate that the band is relation to the cultivars" resistance, The infected of virus induced a new band (Rf 0.471) appearing in resistant and half- susceptible variety. At three-leaf stage and five-leaf stage, isozymes of POD in resistant are much more than those in susceptible variety. This study also tests that there are POD isozyme in maize relating to the resistance to MRDV.EST isozyme appearing of different variety has relationship with the growth duration of maize. There are 4 bands of EST isozyme at three-leaf and five-leaf stage, and only 2 bands at heading stage. There is no difference in the isozyme between the resistant and susceptible variety. After infected by virus, the number of isozyme is still 2, but the colour become heavy. The change shows that the infection can induce the activity of EST.Study on the SOD isozyme in different resistant varieties shows that, there are no relation between the SOD isozyme and the resistance to MRDV, the number of each variety is same, and only increase a band at five-leaf stage. At the heading stage, the SOD isozyne bands have changed much more, there are only 2 bands in resistant and half-susceptible variety, but 4 in high- susceptible variety, which show that, the bands are related to susceptibility, and this relationship is contact to the growth duration. New isozyme protein has been induced by the infect of virus.After infected by MRDV, new PPO isozyme zone has appeared, this result tests that these new zones have some relationship to the susceptible variety, the number of which is 5.