Characterization of <i>CiWRI1</i> from <i>Carya illinoinensis</i> in Seed Oil Biosynthesis

• Main Authors: Xiaofeng Zhou, Yuqiu Dai, Haijun Wu, Peiqiao Zhong, Linjie Luo, Yangjuan Shang, Pengpeng Tan, Fangren Peng, Zhaoxia Tian
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Forests
• Subjects: pecan oil content; fatty acid synthesis; <i>CiWRI1</i>; <i>CiBCCP2</i>
• Online Access: https://www.mdpi.com/1999-4907/11/8/818

Pecan (<i>Carya illinoinensis</i>) is a widely consumed edible woody oil species that is rich in unsaturated fatty acids (FAs) that are beneficial to human health. However, the genes and mechanisms regulating seed oil biosynthesis in pecan are not well understood. Here, we analyzed the expression patterns of genes involved in seed oil biosynthesis in two different varieties of pecan with distinct fruit maturation schedules and oil contents. We cloned the <i>C. illinoinensis WRINKLED 1</i> (<i>CiWRI1</i>) gene, a homolog of <i>Arabidopsis</i><i>WRINKLED1</i> (<i>AtWRI1</i>), which plays a key role in FA synthesis. Overexpressing <i>CiWRI1</i> restored lipid synthesis in the <i>Arabidopsis</i><i>wri1-1</i> mutant and rescued other phenotypic defects such as plant height, root length, and germination rate, suggesting that <i>CiWRI1</i> is an ortholog of the <i>AtWRI1</i> and is involved in the regulation of FA synthesis. To investigate the mechanism of <i>CiWRI1</i> regulation, we cloned <i>C. illinoinensis BIOTIN CARBOXYL CARRIER PROTEIN ISOFORM</i><i>2</i> (<i>CiBCCP2</i>) and determined that the CiWRI1 protein directly binds to an ASML1/WRI1 (AW)-box motif in the <i>CiBCCP2</i> gene promoter and thereby activates its transcription. <i>CiBCCP2</i> overexpression partly rescued the phenotypic defects of the <i>wri1-1</i> mutant, indicating that it is directly regulated by CiWRI1. Thus, de novo FA biosynthesis in seed is conserved across plant species; moreover, CiWRI1 regulates oil synthesis by directly controlling <i>CiBCCP2</i> expression. These findings present novel potential targets for molecular-marker-assisted breeding of this commercially important plant.