SlSWEET1a is involved in glucose import to young leaves in tomato plants
| Autor: | Li Hsuan Ho, Patrick A.W. Klemens, H. Ekkehard Neuhaus, Woei Jiun Guo, Han Yu Ko, Shu Ying Hsieh |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Physiology
Allocation Plant Science phloem SWEET Solanum lycopersicum Arabidopsis Glucose import Hexose Sugar Plant Proteins chemistry.chemical_classification biology fungi Micro-tom food and beverages Biological Transport Protoplast sink and source biology.organism_classification Research Papers Yeast uniporter Plant Leaves Glucose Biochemistry chemistry sugar transport Efflux Phloem Photosynthesis and Metabolism |
| Zdroj: | Journal of Experimental Botany |
| ISSN: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/erz154 |
| Popis: | Silencing expression of SlSWEET1a substantially reduced hexose accumulation in young leaves of tomato plants, revealing the key role of SlSWEET1a in glucose import to sink leaves. Sugar allocation from source to sink (young) leaves, critical for plant development, relies on activities of plasma membrane sugar transporters. However, the key sugar unloading mechanism to sink leaves remains elusive. SWEET transporters mediate sugar efflux into reproductive sinks; therefore, they are promising candidates for sugar unloading during leaf growth. Transcripts of SlSWEET1a, belonging to clade I of the SWEET family, were markedly more abundant than those of all other 30 SlSWEET genes in young leaves of tomatoes. High expression of SlSWEET1a was also detected in reproductive sinks, such as flowers. SlSWEET1a was dominantly expressed in leaf unloading veins, and the green fluorescent protein (GFP) fusion protein was localized to the plasma membrane using Arabidopsis protoplasts, further implicating this carrier in sugar unloading. In addition, yeast growth assays and radiotracer uptake analyses further demonstrated that SlSWEET1a acted as a low-affinity (Km ~100 mM) glucose-specific carrier with a passive diffusion manner. Finally, virus-induced gene silencing of SlSWEET1a expression reduced hexose accumulation to ~50% in young leaves, with a parallel 2-fold increase in mature leaves. Thus, we propose a novel function for SlSWEET1a in the uptake of glucose into unloading cells as part of the sugar unloading mechanism in sink leaves of tomato. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|