AUTHOR=Li Mengyao , Li Xiaoyan , Zhou Jin , Sun Yue , Du Jiageng , Wang Zhuo , Luo Ya , Zhang Yong , Chen Qing , Wang Yan , Lin Yuanxiu , Zhang Yunting , He Wen , Wang Xiaorong , Tang Haoru 

TITLE=Genome-wide identification and analysis of terpene synthase (TPS) genes in celery reveals their regulatory roles in terpenoid biosynthesis

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1010780

DOI=10.3389/fpls.2022.1010780

ISSN=1664-462X

ABSTRACT=<p>Terpenes are an important class of secondary metabolites in celery, which determine its flavor. Terpene synthase (<italic>TPS</italic>) has been established as a key enzyme in the biosynthesis of terpenes. This study systematically analyzed all members of the <italic>TPS</italic> gene family of celery (<italic>Apium graveolens</italic>) based on whole genome data. A total of 39 celery <italic>TPS</italic> genes were identified, among which TPS-a and TPS-b represented the two largest subfamilies. 77 <italic>cis</italic>-element types were screened in the promoter regions of <italic>AgTPS</italic> genes, suggesting the functional diversity of members of this family. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that <italic>AgTPS</italic> genes were enriched in multiple terpenoid biosynthesis pathways. Transcript abundance analysis and qRT-PCR showed that most <italic>AgTPS</italic> genes were differentially expressed in different tissues and colors of celery, with <italic>AgTPS 6, 9, and 11</italic> expressed differentially in tissues, while <italic>AgTPS31</italic>, <italic>32</italic>, and <italic>38</italic> are expressed differently in colors. More than 70% of the celery volatile compounds identified by HS-SPME-GC/MS were terpene, and the most critical compounds were β-Myrcene, D-Limonene, β-Ocimene and γ-Terpinene. Principal component analysis (PCA) showed that compounds (E)-β-Ocimene, D-Limonene, β-Myrcene and γ-Terpinene predominantly accounted for the variation. Further correlation analysis between gene expression and terpenoid accumulation showed that the four genes <italic>AgTPS9</italic>, <italic>25</italic>, <italic>31</italic> and <italic>38</italic> genes may have positive regulatory effects on the synthesis of D-Limonene and β-Myrcene in celery. Overall, this study identified key candidate genes that regulate the biosynthesis of volatile compounds and provide the foothold for the development and utilization of terpenoids in celery.</p>