Maize ZmPROPep1 Transformation And Pyramid Breeding Of Transgenic Disease-resistance Genes

Maize is the foremost food crop and most produced food among the world top seven cereals. Maize sheath blight is the main disease of maize caused by Rhizoctonia solani kühn, seriously affected the production of maize. Maize sheath blight can use synthetic fungicides to control, but the use of fungicides has been limited, because of their carcinogenicity, teratogenicity, high residual toxicity, long degradation time, effects on environmental pollution and possible affect human health. Genetic improvement of host resistance is the best way of disease management. Zm PROPep1 gene is a maize endogenous gene, which is expressed in response to jasmonic acid(JA) treatment and fungal infection. In this study we used the Agrobacterium-mediated method introduced the Zm PROPEP1 gene into maize, therefore the Zm PROPep1 gene is constitutively expressed. The expression of Zm PROPEP1 gene doesn’t need to have a fungal infection. Our lab have got the transgenic maize which respectively containing Iap and P35 genes, Chi and Glu genes, Tlp and Ace genes, Pti and Rs genes, at the same time using maize traditional cross and backcross method, to obtain the transgenic plants which have multiple resistance genes and have better resistance to maize sheath blight.About 70 transgenic maize plants(T0) were obtained by transferring the Zm PROPep1 gene into the maize inbred lines A188, Hi Ⅱ and Z31 using Agrobacuterium-mediated transformation. Nested PCR analyses showed that 23 transgenic maize plants appeared PCR positive which had the target gene. The transformants were selected by treating with the herbicide 0.01% Basta. Only the seeds from herbicide-resistant and PCR-positive plants were reserved. Resistance of transformed plants was tested against Rhizoctonia solani by using detached leaf assay. The activity related to defense was determined by sampling the maize leaves with each treatment administrated at an interval of 12 h to 72 h. The detached leaves were evaluated for necrotic lesions at 3 dpi. The transgenic plants caused different degrees of necrosis phenotypes compared with the WT line. Visual observations on transgenic lines revealed a pronounced decrease in the area of necrosis.Planting genetically modified maize which contains different genes and testing them with PCR, Basta, Rhizoctonia solani kühn and gene expression. Then we use the traditional maize hybrids method, the F1 lines which PCR-positive plants crossed with others, in order to get the transgenic plants which expressing the inhibit apoptosis genes, the confer resistance to fungal pathogens genes and Induce an immune response genes, further improve resistance to sheath blight of maize. In our study we found that coexpression more genes in the progenies of a transgenic maize line revealed an showed resistance to the sheath blight pathogen, Rhizoctonia solani, as compared to that in the lines expressing the individual genes and untransformed plants.