The Biosynthesis Pattern and Transcriptome Analysis of Sapindus saponaria Oil

Xiao Zhou; Lijuan Jiang; Peiwang Li; Jingzhen Chen; Yunzhu Chen; Yan Yang; Luhong Zhang; Yuena Ji; Zhihong Xiao; Kezhai Sheng; Xiaoqian Sheng; Hui Yao; Qiang Liu; Changzhu Li

doi:10.3390/plants13131781

The Biosynthesis Pattern and Transcriptome Analysis of Sapindus saponaria Oil

Plants (Basel). 2024 Jun 27;13(13):1781. doi: 10.3390/plants13131781.

Authors

Xiao Zhou^{1

2}, Lijuan Jiang¹, Peiwang Li², Jingzhen Chen², Yunzhu Chen², Yan Yang², Luhong Zhang^{1

2}, Yuena Ji², Zhihong Xiao^{2

3}, Kezhai Sheng⁴, Xiaoqian Sheng⁵, Hui Yao⁵, Qiang Liu¹, Changzhu Li²

Affiliations

¹ College of Life and Environmental Sciences, Central South University of Forestry and Technology, Changsha 410004, China.
² State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha 410018, China.
³ Key Laboratory of National Forestry and Grassland Administration on Utilization Science for Southern Woody Oilseed, Hunan Academy of Forestry, Changsha 410018, China.
⁴ Hunan Soapberry Agroforestry Development Co., Ltd., Changde 415325, China.
⁵ Shimen County Forestry Bureau, Changde 415300, China.

Abstract

The Sapindus saponaria (soapberry) kernel is rich in oil that has antibacterial, anti-inflammatory, and antioxidant properties, promotes cell proliferation, cell migration, and stimulates skin wound-healing effects. S. saponaria oil has excellent lubricating properties and is a high-quality raw material for biodiesel and premium lubricants, showing great potential in industrial and medical applications. Metabolite and transcriptome analysis revealed patterns of oil accumulation and composition and differentially expressed genes (DEGs) during seed development. Morphological observations of soapberry fruits at different developmental stages were conducted, and the oil content and fatty acid composition of the kernels were determined. Transcriptome sequencing was performed on kernels at 70, 100, and 130 days after flowering (DAF). The oil content of soapberry kernels was lowest at 60 DAF (5%) and peaked at 130 DAF (31%). Following soapberry fruit-ripening, the primary fatty acids in the kernels were C18:1 (oleic acid) and C18:3 (linolenic acid), accounting for an average proportion of 62% and 18%, respectively. The average contents of unsaturated fatty acids and saturated fatty acids in the kernel were 86% and 14%, respectively. Through the dynamic changes in fatty acid composition and DEGs analysis of soapberry kernels, FATA, KCR1, ECR, FAD2 and FAD3 were identified as candidate genes contributing to a high proportion of C18:1 and C18:3, while DGAT3 emerged as a key candidate gene for TAG biosynthesis. The combined analysis of transcriptome and metabolism unveiled the molecular mechanism of oil accumulation, leading to the creation of a metabolic pathway pattern diagram for oil biosynthesis in S. saponaria kernels. The study of soapberry fruit development, kernel oil accumulation, and the molecular mechanism of oil biosynthesis holds great significance in increasing oil yield and improving oil quality.

Keywords: Sapindus saponaria; biodiesel; fatty acid; key enzyme genes; lipid metabolism; oil biosynthesis; soapberry saponin; transcriptome analysis; triacylglycerol; woody oil plant.

Grants and funding

This work was financially supported by the Key Scientific and Technological Innovation Platform of Hunan Province (Grant No. 2023PT1001), the Natural Science Foundation of Hunan Province (Grant No. 2021JJ31143), the Innovation Demonstration Project of Chenzhou City (Grant No. 2022sfq53), the Science and Technology Plan Major Project of Changsha City (Grant No. kq2301004), the Forestry technology research and innovation projects (Grant No. XLKY202205), the State Key Laboratory of Utilization of Woody Oil Resource (Grant No. GZKF202202), and the Graduate Science and Technology Innovation Fund of Central South University of Forestry and Technology (Grant No. CX202101017).