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).

Yanling Zeng,Lin Zhang,Nan Jiang,Xiaofeng Tan,Heping Cao,Marie-Joelle Virolle

doi:10.1371/journal.pone.0107422

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 whereas CoFAD2 gene expression levels were correlated with fatty acid composition 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.

Highlights

Camellia oleifera (Co, tea oil tree) provides high quality edible oil
Unigene 37785 and Unigene 63726 genes did not express much at the initial developmental stage and their expression was down-regulated during the peak stage of oil accumulation (Table 2), suggesting that these two genes might have little effect on lipid biosynthesis in the seeds
This study identified multiple forms of CoFBA genes from seed transcriptome analysis, quantitatively evaluated the expression of four CoFBA genes in developing seeds, along with coding for acyl carrier protein (CoACP), CoSAD and CoFAD2 genes, and analyzed the developmental profiles of oil content and fatty acid composition of tea oil

Summary

Introduction

Camellia oleifera (Co, tea oil tree) provides high quality edible oil. This small tree is originated and widely cultivated in China. Tea oil (Camellia oil) from the seeds is a sweetish seasoning and cooking oil with over 80% monounsaturated fatty acids. Tea oil has anti-microbial and antioxidant properties and known to induce cell cycle arrest and apoptosis in cancerous cell lines [1,4,5]. Tea oil has been shown to have antiulcer effects against ketoprofen-induced oxidative damage in the stomach and intestine [6]. Flavonoids from seed shells have analgesic and anti-inflammatory effects [7,8]. Defattened seeds of the plant have saponins with anti-inflammatory properties [2]. In order to improve tea oil production, many genes coding for key enzymes in tea oil biosynthesis pathway have been identified in the tree [9,10,11,12,13,14]

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