CYCH;1 regulates blue light-mediated stomatal opening by controlling reactive oxygen species homeostasis.

CYCLIN H;1 regulates drought stress responses and blue light-induced stomatal opening by inhibiting reactive oxygen species accumulation in Arabidopsis.

by Zhou X. F., Jin Y. H., Yoo C. Y., Lin X.-L., Kim W.-Y., Yun D.-J., Bressan R. A.,  Hasegawa P. M., Jin J. B. (2013)

Zhou Xiao Feng; Jin Yin Hua; Yoo Chan Yul; Lin Xiao-Lin; Kim Woe-Yeon; Yun Dae-Jin; Bressan Ray A.; Hasegawa Paul M.; Jin Jing Bo

in Plant Physiol. 162, 1030–1041  –

Arabidopsis (Arabidopsis thaliana) CYCLIN-DEPENDENT KINASE Ds (CDKDs) phosphorylate the C-terminal domain of the largest subunit of RNA polymerase II.

Arabidopsis CYCLIN H;1 (CYCH;1) interacts with and activates CDKDs; however, the physiol. function of CYCH;1 has not been determined.

Here, we report that CYCH;1, which is localized to the nucleus, pos. regulates blue light-induced stomatal opening. Reduced-function cych;1 RNA interference (cych;1 RNAi) plants exhibited a drought tolerance phenotype.

CYCH;1 is predominantly expressed in guard cells, and its expression was substantially down-regulated by dehydration. Transpiration of intact leaves was reduced in cych;1 RNAi plants compared with the wild-type control in light but not in darkness.

CYCH;1 down-regulation impaired blue light-induced stomatal opening but did not affect guard cell development or abscisic acid-mediated stomatal closure. Microarray and real-time polymerase chain reaction analyses indicated that CYCH;1 did not regulate the expression of abscisic acid-responsive genes or light-induced stomatal opening signaling determinants, such as MYB60, MYB61, Hypersensitive to red and blue1, and Protein phosphatase7.

CYCH;1 down-regulation induced the expression of redox homeostasis genes, such as LIPOXYGENASE3 (LOX3), LOX4, ARABIDOPSIS GLUTATHIONE PEROXIDASE 7 (ATGPX7), EARLY LIGHT-INDUCIBLE PROTEIN1 (ELIP1), and ELIP2, and increased hydrogen peroxide production in guard cells.

Furthermore, loss-of-function mutations in CDKD;2 or CDKD;3 did not affect responsiveness to drought stress, suggesting that CYCH;1 regulates the drought stress response in a CDKD-independent manner.

We propose that CYCH;1 regulates blue light-mediated stomatal opening by controlling reactive oxygen species homeostasis.


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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