Stomatal response to changing light

 

 

Stomatal response to changing light by four tree species of varying shade tolerance

by Woods D. B., Turner N. C. (1971)

David B. Woods, Connecticut Agricultural Experiment Station (New Haven, United States)

Neil_Turner2
Neil C. Turner, University of Western Australia, Perth, Australia

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in New Phytol. 70: 77–84 – https://doi.org/10.1111/j.1469-8137.1971.tb02512.x –

https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.1971.tb02512.x

Summary

Stomatal opening and closing was followed with a diffusion porometer in beech (Fagus grandi‐folia Ehrh.), maple (Acer rubrum L.), oak (Quercus rubra L.) and yellow poplar (Liriodendron tulipifera L.) in a situation where illuminance could be changed by placing shades over the trees.

In all four species the stomata opened quicker than they closed. The time to reach an equilibrium stomatal resistance was constant for a species but varied between species, for all changes in illuminance greater than 3000 ft‐candles.

To open to a constant leaf resistance took from 3 minutes in beech to 20 minutes in yellow poplar; oak and maple were intermediate at 12 minutes. Beech required 12 minutes to close to a constant leaf resistance, maple 18, oak 20, and yellow poplar 36 minutes.

When the change in illuminance was less than 3000 ft‐candles, the stomata took longer to reach a new equilibrium in all species except yellow poplar. Also beech stomata opened and closed in dimmer light than yellow poplar.

The rates of stomatal opening and closing correlated well with the known shade tolerance of the species.

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A prominent role of protein kinase CK2 in ABA signaling and related processes in stomata

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(A) Regulation of ABA signaling by the control of protein turnover. In the absence of ABA, major regulators of the hormone such as the PYR/PYL/RCAR receptors, the SnRK2 kinases, and several transcription factors (ABI3, ABI5, ABF1, ABF3) are degraded by the proteasome, and/or inactivated. In this way the output of the ABA signal is thoroughly dampened in the absence of the hormone. When ABA levels rise, these major regulators are protected from degradation through the inactivation or degradation of the negative regulators such as KEG. CK2 is known to mediate the stabilization and destabilization of proteins in other systems and is a likely candidate to also have a role as a housekeeping kinase controlling protein turnover in ABA signaling. (B) Integration of the plant circadian clock on ABA signaling. The core circadian clock consists of a negative feedback loop between the CCA1 and LHY on one hand and TOC1 on the other. ABA treatment induces TOC1 expression and, in another feedback loop, TOC1 attenuates ABA signaling and negatively regulates the expression of ABA signaling genes like ABAR, known to interact with the ABA central signaling complex. CCA1 an LHY act synergistic to ABA and antagonistic to TOC1 expression. CCA1 and LHY are phosphorylated by CK2 targeting them for degradation, promoting CCA1 dimerization, CCA1-DNA complex formation, and interaction with the promoters of downstream genes. ABAR is also a substrate of CK2 and, even though the effects of this activity are still unknown, they could include protein turnover and altered gene expression by retrograde signaling from the chloroplast.

 

Emerging roles of protein kinase CK2 in abscisic acid signaling

by Vilela B., Pagès M., Riera M. (2015)

Belmiro Vilela, CRAG Centre for Research in Agricultural Genomics (Barcelona, Spain)

Montserrat_Pages
Montserrat Pagès, CRAG Centre for Research in Agricultural Genomics (Barcelona, Spain)
Marta_Riera
Marta Riera, Spanish National Research Council, Madrid, Spain

 

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in Front. Plant Sci. 6:966. – doi: 10.3389/fpls.2015. 00966 –

https://www.ncbi.nlm.nih.gov/pubmed/26579189

Abstract

The phytohormone abscisic acid (ABA) regulates many aspects of plant growth and development as well as responses to multiple stresses.

Post-translational modifications such as phosphorylation or ubiquitination have pivotal roles in the regulation of ABA signaling. In addition to the positive regulator sucrose non-fermenting-1 related protein kinase 2 (SnRK2), the relevance of the role of other protein kinases, such as CK2, has been recently highlighted.

We have recently established that CK2 phosphorylates the maize ortholog of open stomata 1 OST1, ZmOST1, suggesting a role of CK2 phosphorylation in the control of ZmOST1 protein degradation (Vilela et al., 2015).

CK2 is a pleiotropic enzyme involved in multiple developmental and stress-responsive pathways.

This review summarizes recent advances that taken together suggest a prominent role of protein kinase CK2 in ABA signaling and related processes.