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The homo/heterodimers of plasma membrane sugar transporters CsSWEET1a and CsSWEET17 mediate growth and cold stress tolerance
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  • Lina Yao,
  • Changqing Ding,
  • Xinyuan Hao,
  • Jianming Zeng,
  • Yajun Yang,
  • Xinchao Wang,
  • Lu Wang
Changqing Ding
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Xinyuan Hao
Chinese Academy of Agricultural Sciences Tea Research Institute
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Jianming Zeng
Chinese Academy of Agricultural Sciences Tea Research Institute
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Yajun Yang
Tea research institute
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Xinchao Wang
Tea research institute
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Lu Wang
Tea research institute
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Abstract

Sugars will eventually be exported transporters (SWEET) are involved in plant biological processes. CsSWEET1a and CsSWEET17, were found to be induced by cold acclimation in Camellia sinensis. Particularly, CsSWEET17 was differentially alternatively spliced and its inclusion/exclusion ratio was higher in the cold-resistant cultivar than in the cold-susceptible cultivars. Both CsSWEET1a and CsSWEET17 were located in the plasma membrane, and their interaction was confirmed using yeast two-hybrid and biomolecular fluorescence complementation. The C-terminal of the CsSWEET17, which was different from AtSWEET17, did not affect its plasma membrane localization but promoted its sugar transport activities. Overexpression (OE) of CsSWEET1a and CsSWEET17 resulted in an increased uptake of sugars in Arabidopsis, affecting plant germination and growth. The leaf and seed size of CsSWEET17-OE lines were significantly bigger than wild-type. Moreover, OE of CsSWEET1a and CsSWEET17 significantly reduced the relative electrolyte leakage levels under cold stress. Compared with those in wild-type, the expressions of AtCWINV genes were suppressed in both CsSWEET1a-OE and CsSWEET17-OE lines, indicating the alteration of sugar contents in the cell wall of OE lines. Our results suggest that CsSWEET1a and CsSWEET17 form homo/heterodimers in the plasma membrane to import sugars into the cytoplasm, thereby regulating plant growth and cold tolerance.