Acta Agriculturae Zhejiangensis ›› 2026, Vol. 38 ›› Issue (8): 1598-1609.DOI: 10.3969/j.issn.1004-1524.20250609

• Horticultural Science • Previous Articles     Next Articles

Cloning, expression pattern, and enzyme activity analysis of the phenylalanine ammonia-lyase gene (EmPAL) in Euphorbia maculata

WU Qingyang1(), GUI Mingming2, SONG Meiling1, GUO Sanbao3, ZHANG Zhigao4, HUANG Shenghe2,*()   

  1. 1 Department of Basic Medicine, Fuzhou Medical College, Fuzhou 344000, Jiangxi, China
    2 Key Laboratory of Jianchangbang Traditional Chinese Medicine Research of Jiangxi Education Institutes, Fuzhou Medical College, Fuzhou 344000,Jiangxi, China
    3 Department of Pharmacy, Fuzhou Medical College, Fuzhou 344000,Jiangxi, China
    4 Fuzhou Branch of Jiangxi Tobacco Company, Fuzhou 344000,Jiangxi, China
  • Received:2025-09-18 Online:2026-08-25 Published:2026-09-14

Abstract:

This study aimed to elucidate the structure and protein function of the phenylalanine ammonia-lyase gene (EmPAL), a structural gene in the flavonoid biosynthesis pathway in the medicinal plant Euphorbia maculata, and to provide a basis for further functional investigation of EmPAL. Using E. maculata as the material, the open reading frame (ORF) and promoter sequence of EmPAL were cloned based on transcriptome data combined with 3'-RACE and Tail-PCR techniques. Bioinformatics tools were employed to analyze the physicochemical properties, structural characteristics, and phylogenetic relationships of EmPAL. The expression pattern of EmPAL in different tissues of E. maculata was examined using quantitative real-time PCR (RT-qPCR). Furthermore, prokaryotic expression was performed and its catalytic function was validated through in vitro enzyme activity assays. The results showed that the ORF of EmPAL was 2 160 bp in length, encoding 719 amino acids. The promoter region contained cis-acting elements related to light response, stress response, and phenylpropanoid metabolism regulation. Tissue-specific expression analysis revealed that EmPAL expression was highest in the roots during the reproductive growth period. The molecular weight of EmPAL protein is 78.17 ku, and its isoelectric point is 6.34. The secondary structure was predominantly composed of alpha helix, the tertiary structure exhibited a typical “sea horse” shape, and the quaternary structure was a tetramer. Prokaryotic expression and in vitro enzyme activity assays confirmed that EmPAL could catalyze the conversion of phenylalanine to trans-cinnamic acid, with an optimal reaction temperature of 60 ℃. This study provides a theoretical foundation for further investigation into the function of EmPAL and its role in regulating the biosynthesis of flavonoids in E. maculata.

Key words: Euphorbia maculata, EmPAL, promoter, cloning, RT-qPCR, prokaryotic expression, enzyme activity

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