An ABA-regulated and Golgi-localized protein phosphatase controls water loss during leaf senescence in Arabidopsis
Article first published online: 1 DEC 2011
© 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd
The Plant Journal
Volume 69, Issue 4, pages 667–678, February 2012
How to Cite
Zhang, K., Xia, X., Zhang, Y. and Gan, S.-S. (2012), An ABA-regulated and Golgi-localized protein phosphatase controls water loss during leaf senescence in Arabidopsis. The Plant Journal, 69: 667–678. doi: 10.1111/j.1365-313X.2011.04821.x
- Issue published online: 6 FEB 2012
- Article first published online: 1 DEC 2011
- Accepted manuscript online: 18 OCT 2011 07:51AM EST
- Received 8 September 2011; accepted 13 October 2011; published online 1 December 2011.
- PP2C-type protein phosphatase;
- ABA signaling transduction pathway;
- stomatal movement;
- leaf senescence
It is known that a senescing leaf loses water faster than a non-senescing leaf and that ABA has an important role in promoting leaf senescence. However, questions such as why water loss is faster, how water loss is regulated, and how ABA functions in leaf senescence are not well understood. Here we report on the identification and functional analysis of a leaf senescence associated gene called SAG113. The RNA blot and GUS reporter analyses all show that SAG113 is expressed in senescing leaves and is induced by ABA in Arabidopsis. The SAG113 expression levels are significantly reduced in aba2 and abi4 mutants. A GFP fusion protein analysis revealed that SAG113 protein is localized in the Golgi apparatus. SAG113 encodes a protein phosphatase that belongs to the PP2C family and is able to functionally complement a yeast PP2C-deficient mutant TM126 (ptc1Δ). Leaf senescence is delayed in the SAG113 knockout mutant compared with that in the wild type, stomatal movement in the senescing leaves of SAG113 knockouts is more sensitive to ABA than that of the wild type, and the rate of water loss in senescing leaves of SAG113 knockouts is significantly reduced. In contrast, inducible over-expression of SAG113 results in a lower sensitivity of stomatal movement to ABA treatment, more rapid water loss, and precocious leaf senescence. No other aspects of growth and development, including seed germination, were observed. These findings suggest that SAG113, a negative regulator of ABA signal transduction, is specifically involved in the control of water loss during leaf senescence.