Modification of Lignin Polymers with COMT Anti-Sense Gene in the Jatropha curcas L. by Green Biotechnology Tools

Abstract

Lignin, a complex aromatic polymer, is considered a part of the secondary cell wall. Also, it's called a "cell adhesive" based on provides strength and rigidity to plant tissues and fibers through strong cross-linking with cell wall components. Moreover, lignin acts as a line of defense for plants against biotic and abiotic stresses. In the field of plant biotechnology, particle bombardment remains the most important technique to directly transfer DNA from source to target organ and the most widely used method to generate transgenic plants for commercial purposes. Down-regulation of Jatropha curcas's lignin-producing caffeic acid 3-O-methyltransferase (COMT) gene production pathway led the transgenic plants to develop cell walls. The transgene COMT antisense is used as a selection marker pZMAS-COMT 10,907 bp plasmid (University of Illinois) to confer resistance to glufosinate herbicides under the 35S promoter. Irradiation of embryonic callus with bullet particles introduced the COMT antisense gene and reduced the amount of lignin. Transgenic green callus was used to extract DNA, RNA, and PCR & RT-PCR were performed to detect the presence of genes. A positive sharp band appeared in the green callus, indicating that the gene expression level was downregulated compared to the control. Transgenic shoots and green callus had lower lignin content compared to controls.