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Research Project: Value-Added Products from Cottonseed

Location: Commodity Utilization Research

Title: Identification and expression of fructose-1,6-bisphosphate aldolase genes and their relations to oil content in developing seeds of tea oil tree (Camellia oleifera)

Author
item Zeng, Yanling - Central South University Of Forestry And Technology
item Tan, Xiaofeng - Central South University Of Forestry And Technology
item Zhang, Lin - Hunan University Of Science And Technology
item Jiang, Nan - Hunan University Of Science And Technology
item Cao, Heping

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2014
Publication Date: 9/12/2014
Publication URL: http://handle.nal.usda.gov/10113/59634
Citation: Zeng, Y., Tan, X., Zhang, L., Jiang, N., Cao, H. 2014. Identification and expression of fructose-1,6-bisphosphate aldolase genes and their relations to oil content in developing seeds of tea oil tree (Camellia oleifera). PLoS One. 9(9):e107422. https://doi.org/10.1371/journal.pone.0107422.
DOI: https://doi.org/10.1371/journal.pone.0107422

Interpretive Summary: Camellia oleifera (Co), also called tea oil tree, is a fine edible oil tree originated in China. This small tree is widely cultivated in China and found in forests and foothills. Tea oil or called camellia oil from the pressed seeds is a sweetish seasoning and cooking oil with over 80% monounsaturated fat. The seed residue after oil extraction was widely used for laundry purposes. Recent studies have demonstrated that tea oil is very beneficial to human health. Tea oil is sold as cooking oil in supermarkets throughout China as well as Australia, New Zealand and the United States. Most of the early research efforts were focused on fatty acid analysis of the seeds. In order to fundamentally improve the oil production of Camellia oleifera, many regulatory genes in tea oil biosynthesis pathway have been studied recently. Fructose-1,6-bisphosphate aldolase (FBA) is the key enzyme in the glycolytic pathway. FBA catalyzes a reversible reaction by splitting fructose-1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate; two key intermediates for oil biosynthesis. The objectives of this study were to identify FBA genes, analyze the expression patterns of these genes and investigate the relationship between FBA gene expression and oil content/fatty acid composition in developing seeds of tea oil tree. We identified six forms of CoFBA genes from seed transcriptome analysis, quantitatively evaluated the expression of four CoFBA genes in developing seeds, along with CoACP, CoSAD and CoFAD2 genes, and analyzed the developmental profiles of oil content and fatty acid composition of tea oil. Correlation study indicates that the mRNA levels of CoFBA and CoSAD genes are positively correlated with oil content. We propose that CoFBA and CoSAD are the important factors for determining tea oil yield because CoFBA gene controls the flux of key intermediates for oil biosynthesis and CoSAD gene controls the synthesis of oleic acid, the predominate fatty acid in tea oil. These findings suggest that tea oil yield could be improved by over-expression of CoFBA and CoSAD genes in transgenic plants.

Technical Abstract: Tea oil tree (Camellia oleifera, Co) provides a fine edible oil source in China. Tea oil from the seeds is very beneficial to human health. Fructose-1,6-bisphosphate aldolase (FBA) hydrolyzes fructose-1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, two critical metabolites for oil biosynthesis. The objectives of this study were to identify FBA genes and investigate the relationship between FBA gene expression and oil content in developing seeds of tea oil tree. In this paper, four developmentally up-regulated CoFBA genes were identified in Camellia oleifera seeds based on the transcriptome from two seed developmental stages corresponding to the initiation and peak stages of lipid biosynthesis. The expression of CoFBA genes, along with three key oil biosynthesis genes CoACP, CoFAD2 and CoSAD were analyzed in seeds from eight developmental stages by real-time quantitative PCR. The oil content and fatty acid composition were also analyzed. The results showed that CoFBA and CoSAD mRNA levels were well-correlated with oil content in Camellia seeds. We propose that CoFBA and CoSAD are two important factors for determining tea oil yield because CoFBA gene controls the flux of key intermediates for oil biosynthesis and CoSAD gene controls the synthesis of oleic acid, which accounts for 80% of fatty acids in tea oil. These findings suggest that tea oil yield could be improved by enhanced expression of CoFBA and CoSAD genes in transgenic plants.