Population diversity analyses provide insights into key horticultural traits of Chinese native thymes

Meiyu Sun; Yanan Zhang; Hongtong Bai; Guofeng Sun; Jinzheng Zhang; Lei Shi

doi:10.1093/hr/uhac262

Population diversity analyses provide insights into key horticultural traits of Chinese native thymes

Hortic Res. 2022 Aug 2;10(2):uhac262. doi: 10.1093/hr/uhac262. eCollection 2023 Feb.

Authors

Meiyu Sun^{1

2}, Yanan Zhang^{1

2

3}, Hongtong Bai^{1

2}, Guofeng Sun², Jinzheng Zhang^{1

2}, Lei Shi^{1

2}

Affiliations

¹ Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
² China National Botanical Garden, Beijing 100093, China.
³ University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

Chinese native thymes (CNTs) in the genus Thymus (family Lamiaceae) are rich in bioactive terpenes, which exert antiviral, anti-inflammatory, antioxidation, immunological, and antimicrobial effects. Plants exhibit morphological variation, including erect-type and creeping-type growth forms; however, the molecular mechanisms underlying important horticultural traits have not been determined. Here, we collected 39 CNTs providing strategic plant resources for studies of lignin, terpenoids, and glandular trichomes of thymes. Using resequencing data as well as phenotypic, metabonomic, phylogenetic, population genetic, and transcriptomic analyses, we identified and characterized key genes involved in lignin biosynthesis, terpenoid biosynthesis, and glandular trichome formation. We found many regulatory genes or transcription factors related to these three important horticultural traits, including genes encoding caffeic acid O-methyltransferase (COMT), terpene synthase (TPS), v-myb avian myeloblastosis viral oncogene homolog (MYB), and homeodomain-leucine zipper (HD-ZIP). Population diversity analyses provided insights into growth form, terpenoid, and glandular trichome evolution in CNTs. Furthermore, our results revealed that T. mongolicus accessions might be wild ancestors, and T. quinquecostatus, T. quinquecostatus var. asiaticus, and T. quinquecostatus var. przewalskii might be transitional accessions that derived from T. mongolicus accessions. Finally, T. nervulosus, T. inaequalis, T. mandschuricus, T. curtus, T. amurensis, T. proximus, T. altaicus, T. roseus, and T. marschallianus showed high divergence. We found evidence for introgression between erect-type European cultivated thymes and CNTs. These findings improve our understanding of the determinants of variation in horticultural traits and provide candidate loci for research and breeding.