Seed Transcriptomics Analysis in Camellia oleifera Uncovers Genes Associated with Oil Content and Fatty Acid Composition.

Ping Lin,Changfu Zhou,Kailiang Wang,Xiaohua Yao,Yunhai Xie,Hengfu Yin

doi:10.3390/ijms19010118

Abstract

Camellia oleifera is a major tree species for producing edible oil. Its seed oil is well known for the high level of oleic acids; however, little is known regarding the molecular mechanism of lipid biosynthesis in C. oleifera. Here, we measured the oil contents and fatty acid (FA) compositions at four developmental stages and investigated the global gene expression profiles through transcriptomics sequencing. We identified differentially-expressed genes (DEGs) among the developmental stages and found that the distribution of numbers of DEGs was associated with the accumulation pattern of seed oil. Gene Ontology (GO) enrichment analysis revealed some critical biological processes related to oil accumulation, including lipid metabolism and phosphatidylcholine metabolism. Furthermore, we investigated the expression patterns of lipid biosynthesis genes. We showed that most of the genes were identified with single or multiple copies, and some had correlated profiles along oil accumulation. We proposed that the higher levels of stearoyl-ACP desaturases (SADs) coupled with lower activities of fatty acid desaturase 2 (FAD2) might be responsive to the boost of oleic acid at the late stage of C. oleifera seeds’ development. This work presents a comprehensive transcriptomics study of C. oleifera seeds and uncovers valuable DEGs that are associated with the seed oil accumulation.

Highlights

Camellia oleifera originates from China and is planted widely in south China with a long cultivation history of over 2000 years
We showed that total oil production of kernel increased dramatically at the late stages, and 18:1 was predominantly accumulated during seed maturation
We showed that the number of differentially-expressed genes (DEGs) correlated with the oil accumulation, and more common DEGs were identified across early and late stages of seed development

Summary

Introduction

Camellia oleifera originates from China and is planted widely in south China with a long cultivation history of over 2000 years. As one of the four major oil trees, together with oil palm, olive and coconut, it is known as an important edible oil-bearing tree species in China. It was reported in 2015 that the dry seed production of oil was around ~2.2 million tons over a cultivated area of 4 million ha. C. oleifera has received much more attention owing to its high unsaturated FA contents, which are good for human health. It is widely used in cosmetics, ink, lubricants, etc. It is widely used in cosmetics, ink, lubricants, etc. [4,5]

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