Expression of the Intracellular COPT3-Mediated Cu Transport Is Temporally Regulated by the TCP16 Transcription Factor

• Published in: Frontiers in plant science Vol. 9; p. 910
• Main Authors: Andrés-Colás, Nuria, Carrió-Seguí, Angela, Abdel-Ghany, Salah E, Pilon, Marinus, Peñarrubia, Lola
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 03.07.2018
• Subjects: copper transport; COPT3; heavy metals; Plant Science; TCP16; transcriptional regulation; TCP16; heavy metals; COPT3; transcriptional regulation; copper transport
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2018.00910

Copper is an essential element in plants. When scarce, copper is acquired from extracellular environment or remobilized from intracellular sites, through members of the high affinity copper transporters family COPT located at the plasma membrane and internal membrane, respectively. Here, we show that COPT3 is an intracellular copper transporter, located at a compartment of the secretory pathway, that is mainly expressed in pollen grains and vascular bundles. Contrary to the COPT1 plasma membrane member, the expression of the internal membrane transporter was higher at 12 h than at 0 h of a neutral photoperiod day under copper deficiency. The screening of a library of conditionally overexpressed transcription factors implicated members of the TCP family in the COPT3 differential temporal expression pattern. Particularly, , TCP16 was found to bind to the promoter and down-regulated its expression. Accordingly, was mainly expressed at 0 h under copper deficiency and induced at 12 h by copper excess. Moreover, overexpression resulted in increased sensitivity to copper deficiency, whereas the mutant was sensitive to copper excess. Both copper content and the expression of particular copper status markers were altered in plants with modified levels of Consistent with TCP16 affecting pollen development, the lack of COPT3 function led to altered pollen morphology. Furthermore, analysis of and overexpressing plants revealed that COPT3 function exerted a negative effect on expression. Taken together, these results suggest a differential daily regulation of copper uptake depending on the external and internal copper pools, in which TCP16 inhibits copper remobilization at dawn through repression of intracellular transporters.