Characterization of CiWRI1 from Carya illinoinensis in Seed Oil Biosynthesis

Abstract

Pecan (Carya illinoinensis) 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 C. illinoinensis WRINKLED 1 (CiWRI1) gene, a homolog of ArabidopsisWRINKLED1 (AtWRI1), which plays a key role in FA synthesis. Overexpressing CiWRI1 restored lipid synthesis in the Arabidopsiswri1-1 mutant and rescued other phenotypic defects such as plant height, root length, and germination rate, suggesting that CiWRI1 is an ortholog of the AtWRI1 and is involved in the regulation of FA synthesis. To investigate the mechanism of CiWRI1 regulation, we cloned C. illinoinensis BIOTIN CARBOXYL CARRIER PROTEIN ISOFORM2 (CiBCCP2) and determined that the CiWRI1 protein directly binds to an ASML1/WRI1 (AW)-box motif in the CiBCCP2 gene promoter and thereby activates its transcription. CiBCCP2 overexpression partly rescued the phenotypic defects of the wri1-1 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 CiBCCP2 expression. These findings present novel potential targets for molecular-marker-assisted breeding of this commercially important plant.

Metabolomics and Transcriptomics Analyses Reveal Regulatory Networks Associated with Fatty Acid Accumulation in Pecan Kernels

“…The loss-of-function mutant wri1–1 engenders ∼80% reduction of oil content in Arabidopsis seeds . The overexpression of pecan CiWRI1 in Arabidopsis can restore the wri1–1 mutant phenotypes . Four pecan WRI DEGs were identified; among them, two WRIs (CIL1047S0041 and CIL1187S0078) exhibited higher expression levels, and their expression peaks occurred during the second developmental stage.…”

“…43 The overexpression of pecan CiWRI1 in Arabidopsis can restore the wri1−1 mutant phenotypes. 18 Four pecan WRI DEGs were identified; among them, two WRIs (CIL1047S0041 and CIL1187S0078) exhibited higher expression levels, and their expression peaks occurred during the second developmental stage. LEC1, LEC2, FUS3, and ABI3 are master transcription factors that control seed maturation in plants.…”

“…12,13 A wrinkled 1 (CiWRI1) gene was isolated, whose overexpression in wri1−1 mutant Arabidopsis rescued phenotypic defects via the direct modulation of biotin carboxyl carrier protein subunit (BCCP) gene expression. 18 Considering FA metabolism involves hundreds of genes and complex regulatory networks, 19 the characterization of the transcriptional and metabolic patterns of pecan kernels at different developmental periods may facilitate the investigation of FA biosynthesis in this plant. 20 Recently, metabolomics has risen as a powerful tool to analyze metabolic variations associated with growth and development, 21 abiotic/biotic stress tolerance, 22 and quality formation 23 in various plants.…”

“…FAs are the primary nutrients in pecan kernels. The variations in FAs and their regulatory mechanisms have been investigated during pecan kernel development, and a set of FA-related candidate genes has been identified. , A wrinkled 1 ( CiWRI1 ) gene was isolated, whose overexpression in wri1–1 mutant Arabidopsis rescued phenotypic defects via the direct modulation of biotin carboxyl carrier protein subunit ( BCCP ) gene expression . Considering FA metabolism involves hundreds of genes and complex regulatory networks, the characterization of the transcriptional and metabolic patterns of pecan kernels at different developmental periods may facilitate the investigation of FA biosynthesis in this plant …”

Genome-wide association study and RNA-seq identifies GmWRI1-like transcription factor related to the seed weight in soybean

“…After expressing the exogenous gene AtWRI1 in soybeans, the total oil content increased, and linoleic acid content decreased from 52.4% to 4.6% (Vogel et al, 2019). WRI1 can also directly or indirectly affect the activity of Dof11, ACBP, PDCT, and FAD2 by binding to AW-box cis-acting elements (Zhou et al, 2020). Similar results were reported in our research; we found that the overexpression of GmWRI14-like not only increased the FA content but also significantly increased the SW.…”