Unraveling the Nectar Secretion Pathway and Floral-Specific Expression of <i>SWEET</i> and <i>CWIV</i> Genes in Five Dandelion Species Through RNA Sequencing
<i>Taraxacum</i>, a genus in the Asteraceae family, is widely distributed across temperate regions and plays a vital ecological role by providing nectar and pollen to pollinators during the early flowering season. Floral nectar is a key reward that plants use to attract pollinators, and...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Plants |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2223-7747/14/11/1718 |
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| Summary: | <i>Taraxacum</i>, a genus in the Asteraceae family, is widely distributed across temperate regions and plays a vital ecological role by providing nectar and pollen to pollinators during the early flowering season. Floral nectar is a key reward that plants use to attract pollinators, and its production is tightly regulated by genes such as <i>SWEET</i> sugar transporters and <i>CELL WALL INVERTASE</i> (<i>CWIN</i>), which govern sugar efflux and hydrolysis. Despite their ecological importance, the molecular mechanisms underlying nectar secretion in <i>Taraxacum</i> remain poorly understood. In this study, we performed RNA sequencing of flower tissues from five <i>Taraxacum</i> species—<i>T. coreanum</i>, <i>T. monogolicum</i>, <i>T. ohwianum</i>, <i>T. hallaisanense</i>, and <i>T. officinale</i>—to investigate the expression of nectar-related genes. De novo transcriptome assembly revealed that <i>T. coreanum</i> had the highest unigene count (74,689), followed by <i>T. monogolicum</i> (69,234), <i>T. ohwianum</i> (64,296), <i>T. hallaisanense</i> (59,599), and <i>T. officinale</i> (58,924). Functional annotation and phylogenetic analyses identified 17 putative <i>SWEET</i> and 18 <i>CWIN</i> genes across the five species. Differential gene expression analysis highlighted <i>tarSWEET9</i> and <i>tarCWIN4</i> as consistently up-regulated during the flowering stage. Quantitative PCR in <i>T. officinale</i> further validated that <i>tarSWEET9</i>, <i>tarCWIN4</i>, <i>tarCWIN6</i>, and <i>tarSPAS2</i> show significant expression during floral development but are down-regulated after pollination. These genes are likely central to the regulation of nectar secretion in response to pollination cues. Our findings suggest that <i>T. officinale</i> may have evolved to have an efficient, pollinator-responsive nectar secretion system, contributing to its global adaptability. This study sheds light on how pollinator interactions influence gene expression patterns and may drive evolutionary divergence among <i>Taraxacum</i> species. |
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| ISSN: | 2223-7747 |