Evaluation Of RNA Interference-mediated Transgenic Maize Lines Resistant To Maize Dwarf Mosaic Virus

Maize dwarf mosaic disease is one of the major diseases of maize. Its worldwide distribution is extremely broad, and the harm is very serious. Because of the particularity of maize dwarf mosaic virus spread and infection, leading to the disease prevention and control means is extremely scarce and the effect is not significant. Therefore, breeding varieties of maizes which have resistance to dwarf mosaic virus is a more effective method. With the advantages of high specificity, high resistance, et al, RNA interference technology opens up a new way of the cultivation of genetically modified plants which have significantly enhanced resistance to viral diseases.This study is based on the previous work which has received RNA interference-based genetically modified maize resistant to maize dwarf mosaic virus. We detected their descendant by PCR to screen positive strains. The screened positive strains were planted by a randomized block design, and then inoculated in the fields for identifying the resistance to maize dwarf mosaic virus. Moreover, artificial inoculation method of plant viruses has been technically improved. This study has achieved the following results:(1) The genetically modified maize strains of which the transformed receptors are callus and stem tip were detected by PCR. It is found that the plant positive rate was increased following the generation to generation. The heredities of the maizes are gradually stabilizing.(2) The result of the analysis of variance according to the disease index of the different genetically modified maize strains shows that, compared with the non-transgenetic maize contrast, the resistances to maize dwarf mosaic virus of the genetically modified maize developed from callus in T4and T5generations and the genetically modified maize developed by stem tip transformation in T4generation are significantly enhanced. Thereinto,9lines of the genetically modified maize developed from callus in T4generation,2lines of the maize in T5generation, and4lines of the genetically modified maize developed by stem tip transformation in T4generation are more resistant. Moreover, their all resistance are identified "MR" at least. (3) The degree of injury by the two inoculation method of rubbing a leaf with quartz sands and puncturing a leaf with a glass fiber brush was observed under an inverted microscope. It is obvious that the mechanical injury caused by puncturing a leaf with a glass fiber brush was greatly reduced, and the wound was more uniform. The effect of improved inoculation method is better. The Normality Tests to the genetically modified maize developed from callus in T4and T5generations reveals that the method of puncturing leafs with a glass fiber brush has greatly reduced the random errors in this study compared with the method of rubbing leafs with quartz sands.