Cotton phloem loads from the apoplast using a single member of its nine-member sucrose transporter gene family
© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissionsoup.com.
| Veröffentlicht in: | Journal of experimental botany. - 1985. - 73(2022), 3 vom: 27. Jan., Seite 848-859 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2022
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| Zugriff auf das übergeordnete Werk: | Journal of experimental botany |
| Schlagworte: | Journal Article Research Support, U.S. Gov't, Non-P.H.S. Carbohydrate partitioning cotton esculin membrane transport passive loading phloem loading source to sink sucrose transport mehr... |
| Zusammenfassung: | © The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissionsoup.com. Phloem loading and transport are fundamental processes for allocating carbon from source organs to sink tissues. Cotton (Gossypium spp.) has a high sink demand for the cellulosic fibers that grow on the seed coat and for the storage reserves in the developing embryo, along with the demands of new growth in the shoots and roots. Addressing how cotton mobilizes resources from source leaves to sink organs provides insight into processes contributing to fiber and seed yield. Plasmodesmata frequencies between companion cells and flanking parenchyma in minor veins are higher than expected for an apoplastic loader, and cotton's close relatedness to Tilia spp. hints at passive loading. Suc was the only canonical transport sugar in leaves and constituted 87% of 14C-labeled photoassimilate being actively transported. [14C]Suc uptake coupled with autoradiography indicated active [14C]Suc accumulation in minor veins, suggesting Suc loading from the apoplast; esculin, a fluorescent Suc analog, did not accumulate in minor veins. Of the nine sucrose transporter (SUT) genes identified per diploid genome, only GhSUT1-L2 showed appreciable expression in mature leaves, and silencing GhSUT1-L2 yielded phenotypes characteristic of blocked phloem transport. Furthermore, only GhSUT1-L2 cDNA stimulated esculin and [14C]Suc uptake into yeast, and only the GhSUT1-L2 promoter caused uidA (β-glucuronidase) reporter gene expression in minor vein phloem of Arabidopsis thaliana. Collectively, these results argue that apoplastic phloem loading mediated by GhSUT1-L2 is the dominant mode of phloem loading in cotton |
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| Beschreibung: | Date Completed 10.03.2022 Date Revised 11.03.2022 published: Print Citation Status MEDLINE |
| ISSN: | 1460-2431 |
| DOI: | 10.1093/jxb/erab461 |