ArticleProceedings of the National Academy of Sciences of the United States of America2009
Downregulating the sucrose transporter VpSUT1 in Verbascum phoeniceum does not inhibit phloem loading.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 27 papers.
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27 citing papers in PubMed, 57 citations in OpenAlex.
- The loss of COP1 delays senescence and inhibits root growth through modulation of sucrose allocation and availability.Plant physiology · 2026Article
- Significance of Raffinose Family Oligosaccharides (RFOs) metabolism in plants.Advanced biotechnology · 2024Review
- The transcription factor CmERFI-2 represses CmMYB44 expression to increase sucrose levels in oriental melon fruit.Plant physiology · 2023Article
- Leaf photosynthesis is positively correlated with xylem and phloem areas in leaf veins in rice (Oryza sativa) plants.Annals of botany · 2022Article
- Sucrose Utilization for Improved Crop Yields: A Review Article.International journal of molecular sciences · 2021Review
- Recent Advances in Carbon and Nitrogen Metabolism in C3 Plants.International journal of molecular sciences · 2020Review
- The Chromosome-Scale Genome of Melon Dissects Genetic Architecture of Important Agronomic Traits.iScience · 2020Article
- Long-Distance Movement of mRNAs in Plants.Plants (Basel, Switzerland) · 2020Review
- Heterologous expression of the apple hexose transporter MdHT2.2 altered sugar concentration with increasing cell wall invertase activity in tomato fruit.Plant biotechnology journal · 2020Article
- The Initiation of Inferior Grain Filling is Affected by Sugar Translocation Efficiency in Large Panicle Rice.Rice (New York, N.Y.) · 2019Article
- Article
- Elucidation of the Mechanisms of Long-Distance mRNA Movement in aPlant physiology · 2018Article
- Article
- Phloem Loading through Plasmodesmata: A Biophysical Analysis.Plant physiology · 2017Article
- Suppression of cucumber stachyose synthase gene (CsSTS) inhibits phloem loading and reduces low temperature stress tolerance.Plant molecular biology · 2017Article
- Rice Sucrose Partitioning Mediated by a Putative Pectin Methyltransferase and Homogalacturonan Methylesterification.Plant physiology · 2017Article
- Flagellin peptide flg22 gains access to long-distance trafficking in Arabidopsis via its receptor, FLS2.Journal of experimental botany · 2017Article
- Differential Signaling and Sugar Exchanges in Response to Avirulent Pathogen- and Symbiont-Derived Molecules in Tobacco Cells.Frontiers in microbiology · 2017Article
- Co-expression network analysis reveals transcription factors associated to cell wall biosynthesis in sugarcane.Plant molecular biology · 2016Article
- An update on source-to-sink carbon partitioning in tomato.Frontiers in plant science · 2014Review
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2 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Sucrose is loaded into the phloem in the minor veins of leaves before export. Two active, species-specific loading mechanisms have been proposed. One involves transporter-mediated sucrose transfer from the apoplast into the sieve element-companion cell complex, so-called apoplastic loading. In the putative second mechanism, sucrose follows an entirely symplastic pathway, and the solute concentration is elevated by the synthesis of raffinose and stachyose in the phloem, not by transporter activity. Several sucrose-transporting plants have been shown to be apoplastic loaders by downregulating sucrose transporter 1 (SUT1), leading to accumulation of sugars and leaf chlorosis. In this study we compared the effect of downregulating SUT1 in Nicotiana tabacum, a sucrose transporter, and Verbascum phoeniceum, a species that transports raffinose and stachyose. To test the effectiveness of RNAi downregulation, we measured SUT1 mRNA levels and sucrose-H(+) symport in leaf discs. Mild NtSUT1 downregulation in N. tabacum resulted in the pronounced phenotype associated with loading inhibition. In contrast, no such phenotype developed when VpSUT1 was downregulated in V. phoeniceum, leaving minimal sucrose transport activity. Only those plants with the most severe VpSUT1 downregulation accumulated more carbohydrate than usual and these plants were normal by other criteria: growth rate, photosynthesis, and ability to clear starch during the night. The results provide direct evidence that the mechanism of phloem loading in V. phoeniceum does not require active sucrose uptake from the apoplast and strongly supports the conclusion that the loading pathway is symplastic in this species.
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