Interspecific Variation in the Unsaturation Level of Seed Oils Were Associated With the Expression Pattern Shifts of Duplicated Desaturase Genes and the Potential Role of Other Regulatory Genes.

Mengli Wang,Yuguo Wang,Ji Yang,Zhen Xing,Jinjing Jian,Chengchuan Zhou,Zhiping Song,Wenju Zhang,Yonghong Hu,Lexuan Gao,Gengyun Li

doi:10.3389/fpls.2020.616338

Abstract

Seed oils are of great economic importance both for human consumption and industrial applications. The nutritional quality and industrial value of seed oils are mostly determined by their fatty acid profiles, especially the relative proportions of unsaturated fatty acids. Tree peony seed oils have recently been recognized as novel edible oils enriched in α-linolenic acid (ALA). However, congeneric species, such as Paeonia ostii and P. ludlowii, showed marked variation in the relative proportions of different unsaturated fatty acids. By comparing the dynamics of fatty acid accumulation and the time-course gene expression patterns between P. ostii and P. ludlowii, we identified genes that were differentially expressed between two species in developing seeds, and showed congruent patterns of variation between expression levels and phenotypes. In addition to the well-known desaturase and acyltransferase genes associated with fatty acid desaturation, among them were some genes that were conservatively co-expressed with the desaturation pathway genes across phylogenetically distant ALA-rich species, including Camelina sativa and Perilla frutescens. Go enrichment analysis revealed that these genes were mainly involved in transcriptional regulation, protein post-translational modification and hormone biosynthesis and response, suggesting that the fatty acid synthesis and desaturation pathway might be subject to multiple levels of regulation.

Highlights

Plant storage oils are an essential part of the human diet, providing a number of nutrients the body needs including essential fats and vitamins (Damude and Kinney, 2008)
These results suggested that the differences in seed oil composition between P. ostii and P. ludlowii were unlikely to be plastic changes induced by environmental variation since previous studies have shown increased proportions of unsaturated fatty acids in plants at lower temperatures/higher altitudes (Linder, 2000; Zhang et al, 2015; Guerin et al, 2020), and indicated that the reactions of fatty acid desaturation were controlled by distinct regulatory mechanisms in different organs
The results clearly showed that some of the co-expressed genes were well known as key regulators of seed oil generation, such as the transcription factor WRI1, which was identified to govern the flux of carbon through glycolysis and fatty acid synthesis by regulating genes associated with fatty acid biosynthesis in plastids (Cernac and Benning, 2004; Baud et al, 2007)

Summary

Introduction

Plant storage oils are an essential part of the human diet, providing a number of nutrients the body needs including essential fats and vitamins (Damude and Kinney, 2008). The level of fatty acid unsaturation of oil can directly affect its value and utilization. Polyunsaturated fatty acids, such as linoleic acid (LA), and α-linolenic acid (ALA), are considered to be critical nutrients for human health (Damude and Kinney, 2008), but they are undesirable while being used as biofuel and chemical feedstocks because of their instability in processing, storage and use (Kodali, 2002). The requirements on different optimal fatty acid compositions for different uses have directly led to the growing interest in identifying genetic factors responsible for the variation in seed oil composition to better understand how the relative proportions of fatty acids are regulated in the seed oils derived from different plants

Methods

Results

Discussion

Conclusion