Study On Silencing ZmC4H Gene By RNA Interference Affect The Lignin Content Of Straw In Maize

Maize (Zea Mays L.) straw is mainly composed of lignin, cellulose and hemicelluloses.Lignin has the capacity of enhancing plant stress and transporting water.It is difficult to make effective use of the lignin for the manufacture of paper and biofuel in production,which bringing unnecessary energy waste caused by its quite complex structure.In our study,we try to reduce the content of lignin or change its components by utilizing genetic engineering methods, which will be of great significance.Here,the B73 inbred lines were used as the transgenic materials and the Cinnamate 4-hydroxylase(C4H) is the key enzymes of lignin biosynthesis as target gene for the construction of RNAi vectors.Transferring the vector into maize (zheng58)by Agrobacterium-mediated maize shoot tip transformation and positive transgenic lines have been detected by PCR assay,herbicide resistance and lignin content, the main results are as follows:1、PCR cloning technology are used to get the part of C4H gene sequences, with modified with pUCCRNAi and pCAM1301 contains Bar and CaMV35S carrier as intermediate carrier, through genetic engineering construction of RNA interference carrier pCAM1301+C4H success.2、The expression vector p1301+C4H was introduced into maize zheng58 by shoot tip of maize transformation system. And transgenic plants were screened using herbicide.3、T1 transgenic plants that tested positive by PCR detection were analyzed according to RT-PCR. The result s implied that RNAi reduced the level of ZmC4H expression. Klason lignin and cellulose content of stalks decreased by 23.50%,cellulose content decreased by 8.11% compared with the control.4、Will be red staining of genetically modified strains of stem slice observation under microscopy imaging system, it’s found that the color of the transgenic plants vascular sheath are wild type shallow, prove that inhibit the expression of endogenous genes ZmC4H reducing plant lignin content.5、Fiber length and the crystallinity of gm corn plant straw was measured and found that genetically modified strains of fiber length grew by an average of 8.29%, compared with the control of corn fiber crystallinity values by an average of 17.80% compared with control.In summary, this paper successfully constructed the RNA interference expression vector pCAM1301 + C4H, and pCAMBOl + C4H maize genetic transformation, to obtain transgenic plants. Transgenic maize straw lignin and cellulose content reduced than control, which the fiber drop lower than that of lignin decreased.