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Potassium transport in developing fleshy fruits: the grapevine inward K + channel VvK1.2 is activated by CIPK – CBL complexes and induced in ripening berry flesh cells
Author(s) -
Cuéllar Teresa,
Azeem Farrukh,
Andrianteranagna Mamy,
Pascaud François,
Verdeil JeanLuc,
Sentenac Hervé,
Zimmermann Sabine,
Gaillard Isabelle
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12092
Subject(s) - berry , arabidopsis , potassium channel , xenopus , ripening , flesh , chemistry , biology , botany , biophysics , biochemistry , horticulture , gene , mutant
Summary The grape berry provides a model for investigating the physiology of non‐climacteric fruits. Increased K + accumulation in the berry has a strong negative impact on fruit acidity (and quality). In maturing berries, we identified a K + channel from the Shaker family, V v K 1.2, and two CBL ‐interacting protein kinase ( CIPK )/calcineurin B ‐like calcium sensor ( CBL ) pairs, V v CIPK 04– V v CBL 01 and V v CIPK 03– V v CBL 02, that may control the activity of this channel. Vv CBL 01 and V v CIPK 04 are homologues of Arabidopsis AtCBL1 and AtCIPK23, respectively, which form a complex that controls the activity of the Shaker K + channel AKT 1 in Arabidopsis roots. V v K 1.2 remained electrically silent when expressed alone in Xenopus oocytes, but gave rise to K + currents when co‐expressed with the pairs V v CIPK 03–Vv CBL 02 or V v CIPK 04– V v CBL 01, the second pair inducing much larger currents than the first one. Other tested CIPK – CBL pairs expressed in maturing berries were found to be unable to activate V v K 1.2. When activated by its CIPK – CBL partners, V v K 1.2 acts as a voltage‐gated inwardly rectifying K + channel that is activated at voltages more negative than –100 mV and is stimulated upon external acidification. This channel is specifically expressed in the berry, where it displays a very strong induction at veraison (the inception of ripening) in flesh cells, phloem tissues and perivascular cells surrounding vascular bundles. Its expression in these tissues is further greatly increased upon mild drought stress. V v K 1.2 is thus likely to mediate rapid K + transport in the berry and to contribute to the extensive re‐organization of the translocation pathways and transport mechanisms that occurs at veraison.