Protein phosphorylation is prerequisite for intracellular Ca2+ release and ion channel control by nitric oxide and abscisic acid in guard cells

SOKOLOVSKI, S.; HILLS, A.; GAY, R.; CARLOS GARCIA-MATA; LAMATTINA, L.; BLATT, M. R.

PLANT JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Año: 2005 vol. 43 p. 520 - 529

0960-7412

Recent work has indicated that nitric oxide (NO) and its synthesis are important elements of signal cascades in plant–pathogen defence, and are a prerequisite for drought and abscisic acid (ABA) responses in Arabidopsis thaliana and Vicia faba guard cells. NO regulates inward-rectifying K+ channels and Cl– channels of Vicia guard cells via intracellular Ca2+ release. However, its integration with related signals, including the actions of serine– threonine protein kinases, is less well defined. We report here that the elevation of cytosolic-free [Ca2+] ([Ca2+]i) mediated by NO in guard cells is reversibly inhibited by the broad-range protein kinase antagonists staurosporine and K252A, but not by the tyrosine kinase antagonist genistein. The effects of kinase antagonism translate directly to a loss of NO-sensitivity of the inward-rectifying K+ channels and background (Cl– channel) current, and to a parallel loss in sensitivity of the K+ channels to ABA. These results demonstrate that NO-dependent signals can be modulated through protein phosphorylation upstream of intracellular Ca2+ release, and they implicate a target for protein kinase control in ABA signalling that feeds into NO-dependent Ca2+ release.