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Plant Cell Environ. 2016 Feb;39(2):377-92. doi: 10.1111/pce.12620. Epub 2015 Nov 9.

Ca(2+) -regulated and diurnal rhythm-regulated Na(+) /Ca(2+) exchanger AtNCL affects flowering time and auxin signalling in Arabidopsis.

Author information

1
College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430075, China.
2
Children's Nutrition Research Center, USDA/ARS, Baylor College of Medicine, Houston, TX, 77030, USA.
3
College of Life Science and technology, Huazhong Agricultural University, Wuhan, 430075, China.
4
Department of Horticulture, Forestry and Recreation Resources, Kansas State University, Manhattan, KS, 66506, USA.

Abstract

Calcium (Ca(2+) ) is vital for plant growth, development, hormone response and adaptation to environmental stresses, yet the mechanisms regulating plant cytosolic Ca(2+) homeostasis are not fully understood. Here, we characterize an Arabidopsis Ca(2+) -regulated Na(+) /Ca(2+) exchanger AtNCL that regulates Ca(2+) and multiple physiological processes. AtNCL was localized to the tonoplast in yeast and plant cells. AtNCL appeared to mediate sodium (Na(+) ) vacuolar sequestration and meanwhile Ca(2+) release. The EF-hand domains within AtNCL regulated Ca(2+) binding and transport of Ca(2+) and Na(+) . Plants with diminished AtNCL expression were more tolerant to high CaCl2 but more sensitive to both NaCl and auxin; heightened expression of AtNCL rendered plants more sensitive to CaCl2 but tolerant to NaCl. AtNCL expression appeared to be regulated by the diurnal rhythm and suppressed by auxin. DR5::GUS expression and root responses to auxin were altered in AtNCL mutants. The auxin-induced suppression of AtNCL was attenuated in SLR/IAA14 and ARF6/8 mutants. The mutants with altered AtNCL expression also altered flowering time and FT and CO expression; FT may mediate AtNCL-regulated flowering time change. Therefore, AtNCL is a vacuolar Ca(2+) -regulated Na(+) /Ca(2+) exchanger that regulates auxin responses and flowering time.

KEYWORDS:

Na+/Ca2+ homeostasis; auxin response; flowering time; vacuole

PMID:
26296956
DOI:
10.1111/pce.12620
[Indexed for MEDLINE]

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