Sucrose transporter StSUT4 from potato affects flowering, tuberization, and shade avoidance response.
Sucrose (Suc) transporters belong to a large gene family. The physiological role of SUT1 proteins has been intensively investigated in higher plants, whereas that of SUT4 proteins is so far unknown. All three known Suc transporters from potato (Solanum tuberosum), SUT1, SUT2, and SUT4, are colocalized and their RNA levels not only follow a diurnal rhythm, but also oscillate in constant light. Here, we examined the physiological effects of transgenic potato plants on RNA interference (RNAi)-inactivated StSUT4 expression. The phenotype of StSUT4-RNAi plants includes early flowering, higher tuber production, and reduced sensitivity toward light enriched in far-red wavelength (i.e. in canopy shade). Inhibition of StSUT4 led to tuber production of the strict photoperiodic potato subsp. andigena even under noninductive long-day conditions. Accumulation of soluble sugars and Suc efflux from leaves of transgenic plants are modified in StSUT4-RNAi plants, leading to modified Suc levels in sink organs. StSUT4 expression of wild-type plants is induced by gibberellins and ethephon, and external supply of gibberellic acid leads to even more pronounced differences between wild-type and StSUT4-RNAi plants regarding tuber yield and internode elongation, indicating a reciprocal regulation of StSUT4 and gibberellins.
Chincinska
Izabela A
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Institute of Biology, Plant Physiology, Humboldt University, 10115 Berlin, Germany.
Liesche
Johannes
J
Krügel
Undine
U
Michalska
Justyna
J
Geigenberger
Peter
P
Grimm
Bernhard
B
Kühn
Christina
C
D050260:Carbohydrate Metabolism; D002462:Cell Membrane / Q000378:metabolism; D035264:Flowers / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005875:Gibberellins / Q000378:metabolism; D008027:Light; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018524:Phototropism / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D035281:Plant Tubers / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
D005875:Gibberellins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; C078729:sucrose transport protein, plant; C007842:gibberellic acid