Isolation and Functional Analysis of the <i>DhMYB2</i> and <i>DhbHLH1</i> Promoters from <i>Phalaenopsis</i>-Type <i>Dendrobium</i> Involved in Stress Responses and Tissue-Specific Expression
<i>Phalaenopsis</i>-type <i>Dendrobium</i> (Den-Phals) is a commercially valuable orchid, with floral color being key to its market appeal. Despite the significance of anthocyanin biosynthesis in color development, its transcriptional regulation in Den-Phals remains unclear....
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Horticulturae |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2311-7524/11/5/550 |
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| Summary: | <i>Phalaenopsis</i>-type <i>Dendrobium</i> (Den-Phals) is a commercially valuable orchid, with floral color being key to its market appeal. Despite the significance of anthocyanin biosynthesis in color development, its transcriptional regulation in Den-Phals remains unclear. This study functionally characterized the promoters of <i>DhMYB2</i> and <i>DhbHLH1</i>, two key transcription factors involved in anthocyanin biosynthesis. A 1864 bp <i>DhMYB2</i> promoter and a 1995 bp <i>DhbHLH1</i> promoter were isolated using genome walking. Bioinformatics analysis identified <i>cis</i>-acting elements associated with abiotic stress responses, phytohormone signaling, and floral-specific regulation. 5′-Deletion analysis in tobacco leaves identified core regulatory regions for the <i>DhMYB2</i> promoter (−1864 to −937 bp) and <i>DhbHLH1</i> promoter (−1995 to −924 bp). GUS staining and activity assays demonstrated that the activities of the <i>DhMYB2</i> and <i>DhbHLH1</i> promoters were significantly increased under treatments of long light, low temperature, drought, salicylic acid (SA), and abscisic acid (ABA), while the <i>DhbHLH1</i> promoter was also induced by methyl jasmonate (MeJA) and indole-3-acetic acid (IAA). Furthermore, promoter activity of <i>DhMYB2</i> and <i>DhbHLH1</i> was detected only in transgenic <i>Arabidopsis</i> flowers, suggesting that these promoters exhibit floral-specific activity. This study provides the first functional analysis of Den-Phals anthocyanin promoters, revealing their stress-responsive nature and floral specificity, which will facilitate molecular breeding of novel orchid cultivars. |
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| ISSN: | 2311-7524 |