Tissue Culture And Single Nucleotide Polymorphisms Of Fad2 Gene From Vernicia Fordii, A Potential Biodiesel Plant

Vernicia fordii is an oil-producing tree with multiple uses, especially with its great potential in energy application. However, the perennial and outcrossing characteristics of tung tree make it difficult to develop new cultivars and maintain elite cultivars through sexual reproduction. Therefore, high-frequency asexual propagation of tung tree is badly needed for large-scale demand and continuous supply of elite cultivars. On the other hand, genetic diversity and single nucleotide polymorphism (SNP) providing an abundant source of DNA polymorphisms are essential for manipulate seed oil composition of tung tree using genetic and genomic approaches for a variety of applications in industry and energy. In this thesis, I not only introduced a simple and reproducible protocol for induction of adventitious shoot buds from leaf tissues of tung tree, but also reported some information about fad2 gene variation in tung tree.As to tissue culture of tung, the highest shoot regeneration frequency (93.1%) from young leaf explants was recorded on MS medium supplemented with BA (13.30μM) and IBA (2.46μM). After six weeks of being cultured, well induced buds were transferred to MS medium supplemented with BA (8.88μM), NAA (1.35μM) and GA3 (1.44μM) which recorded the maximum shoot proliferation rate (4.44). Significant differences were observed on adventitious buds vigor and regeneration capacity among genotypes. AFLP analysis suggested that the significant differences among genotypes for direct organogenesis from leaf tissues were attributed to genetic background.In SNP analysis for fad2 gene, a 1.2-kb coding region of the gene encoding oleate desaturaseed was surveyed by sequencing a sample of 38 nationwide V. fordii genotypes. Two SNPs were detected, giving an average SNP frequency of 1/576 bases. Although the number of SNPs is small, the two SNPs resulted in changed amino acids. Further analysis of the fatty acid compositions for the mutant accessions suggested that the two SNPs in the fad2 coding region were likely to increase levels of polyunsaturated fatty acids, especially the content of eleostearic to acclimate to the low temperature. This characterization of the fad2 gene from tung tree and its effect on lipid metabolism should provide new insights into the regulation of seed lipid metabolism. It is feasible to manipulate seed oil composition of tung tree using genetic and genomic approaches for a variety of applications in industry and energy.