Transcriptional Analysis of Different Cultivars and Genome-Wide Identification of FAD Gene Family in Tree Peony

Abstract

The tree peony (Paeonia ostii), a newly recognized woody oil plant endemic to China, is noteworthy for its high content of unsaturated fatty acids (UFA), particularly alpha-linolenic acid (ALA). Fatty acid desaturases (FADs) are integral to plant development and defense mechanisms. Nonetheless, there is limited understanding of (i) the molecular mechanism underlying FA biosynthesis in various varieties during seed maturation and (ii) a genome-wide analysis of FAD family genes within the tree peony. We selected three distinct cultivars of tree peony for transcriptome sequencing and performed an extensive analysis of PoFAD genes. In total, 67,542 unigenes were acquired and annotated with six protein databases available to the public. Forty-one differentially expressed genes (DEGs) pertinent to FA biosynthesis and lipid metabolism were identified in this study. Notably, genes such as PoFAD2, PoFAD6, and PoSAD were found to be significantly upregulated, contributing to a differential linolenic acid and linoleic acid content across the three cultivars. Herein, 24 PoFADs from the P. ostii genome were recognized and categorized into four distinct clusters according to their conserved structural features. The distribution of PoFADs was found to be random and uneven across five chromosomes, indicating a complex genomic architecture. Six colinear gene pairs were found between P. ostii and V. vinifera, indicating a potential link due to their close relationship. Together, these findings significantly enhance our knowledge of the molecular processes governing fatty acid synthesis, elucidate the functional roles of the FAD gene family, and lay the groundwork for using genetic manipulation to boost lipid levels.