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Acta Prataculturae Sinica ›› 2019, Vol. 28 ›› Issue (11): 159-167.DOI: 10.11686/cyxb2018755

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Expression analysis of SaLDC promoter from Sophora alopecuroides in Arabidopsis thaliana

LU Shan-shan1,2,3, HONG Yuan-shu1,2, LIU Ping1,2,*   

  1. 1.Key Laboratory of Modern Molecular Breeding for Dominant and Special Crops in Ningxia, Yinchuan 750021, China;
    2.College of Agronomy, Ningxia University, Yinchuan 750021, China;
    3.Qingdao Qiushi College, Qingdao 266109, China
  • Received:2018-11-28 Online:2019-11-20 Published:2019-11-20
  • Contact: *. E-mail: liupnxdx@126.com

Abstract: Lysine decarboxylase (LDC) gene is the first key enzyme gene in oxymatrine (OMA) biosynthesis in Sophora alopecuroides. The promoter sequence (1260 bp, gene bank accession number: KY038928) upstream of the gene (SaLDC) encoding lysine decarboxylase was cloned from S. alopecuroides genomic DNA. Its promoter activity was evaluated by transient expression in S. alopecuroides callus. A bioinformatics analysis showed that the promoter sequence contains a TATA-box, a CAAT-box, and other cis-acting elements such as drought-responsive, light-responsive, defense-responsive, stress-responsive elements, methyl jasmonate-responsive element, and tissue-specific expression element. To further study the functionality of the SaLDC promoter, a plant expression vector with the SaLDC promoter sequence fused to the GUS reporter gene (encoding β-glucuronidase) was transferred into Arabidopsis thaliana by Agrobacterium. β-glucuronidase activity was quantified by GUS staining and quantitative assays. We detected GUS activity in T2 transgenic A. thaliana seedlings at different growth stages and in tissues of the adult plants. During seedling growth, GUS activity in the leaves decreased. In adult plants, GUS activity was higher in the leaves and calyxes than in the roots, stems, petals and pods. The expression of GUS was induced by simulated drought (polyethylene glycol, PEG) stress and light in transgenic A. thaliana. Quantitative analyses showed that GUS activity increased significantly in the early stage of PEG stress (1-2 h) (P<0.05) and then decreased to a minimum at 8 h (P<0.01), to around 28.2% of its original level. All these results show that the SaLDC promoter confers tissue-specific and spatio-temporal-specific expression, and that the expression of this structural gene is regulated by light and drought stress.

Key words: Sophra alopecuroides, lysine decarboxylase (LDC), SaLDC promoter, expression analysis