HT1 is essential for red light-induced stomatal opening and interacts genetically with OST1 during stomatal responses to red light and altered [CO2 ]

The HT1 protein kinase is essential for red light-induced stomatal opening and genetically interacts with OST1 in red light and CO2 -induced stomatal movement responses

by Matrosova A., Bogireddi H., Mateo-Peñas A., Hashimoto-Sugimoto M., Iba K., Schroeder J. I., Israelsson-Nordström M. (2015)

Matrosova A¹, Bogireddi H¹, Mateo-Peñas A¹, Hashimoto-Sugimoto M², Iba K², Schroeder JI³, Israelsson-Nordström M¹.

1 Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden.

2 Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, 812-8581, Japan.

3 Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, La Jolla, CA, 92093-0116, USA.

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In New Phytol. 208(4): 1126-1137 – doi: 10.1111/nph.13566 – Epub 2015 Jul 20 –

https://www.ncbi.nlm.nih.gov/pubmed/26192339

Abstract

The question of whether red light-induced stomatal opening is mediated by a photosynthesis-derived reduction in intercellular [CO2 ] (Ci ) remains controversial and genetic analyses are needed. The Arabidopsis thaliana protein kinase HIGH TEMPERATURE 1 (HT1) is a negative regulator of [CO2 ]-induced stomatal closing and ht1-2 mutant plants do not show stomatal opening to low [CO2 ]. The protein kinase mutant ost1-3 exhibits slowed stomatal responses to CO2 . The functions of HT1 and OPEN STOMATA 1 (OST1) to changes in red, blue light or [CO2 ] were analyzed. For comparison we assayed recessive ca1ca4 carbonic anhydrase double mutant plants, based on their slowed stomatal response to CO2 . Here, we report a strong impairment in ht1 in red light-induced stomatal opening whereas blue light was able to induce stomatal opening. The effects on photosynthetic performance in ht1 were restored when stomatal limitation of CO2 uptake, by control of [Ci ], was eliminated. HT1 was found to interact genetically with OST1 both during red light- and low [CO2 ]-induced stomatal opening. Analyses of ca1ca4 plants suggest that more than a low [Ci ]-dependent pathway may function in red light-induced stomatal opening. These results demonstrate that HT1 is essential for red light-induced stomatal opening and interacts genetically with OST1 during stomatal responses to red light and altered [CO2 ].

ABA, CO2 and Ca2+ in stomata

 

Guard cell ABA and CO₂ signaling network updates and Ca²⁺ sensor priming hypothesis.

by Israelsson M., Siegel R. S.,

 Young J.,

 Hashimoto-Sugimoto M., Iba K.

 Schroeder J. I.

(2006)

 in Current Opinion in Plant Biology 9, 654–663. – doi:10.1016/j.pbi.2006.09.006

CrossRefMedlineWeb of Science

http://cel.webofknowledge.com/InboundService.do?product=CEL&SID=Q1KxcDMHKXP3N1gwe6c&UT=WOS%3A000242057800015&SrcApp=Highwire&action=retrieve&Init=Yes&SrcAuth=Highwire&Func=Frame&customersID=Highwire&IsProductCode=Yes&mode=FullRecord

Abstract

Stomatal pores in the epidermis of plants enable gas exchange between plants and the atmosphere, a process vital to plant life. Pairs of specialized guard cells surround and control stomatal apertures.

Stomatal closing is induced by abscisic acid (ABA) and elevated CO₂ concentrations. Recent advances have been made in understanding ABA signaling and in characterizing CO₂ transduction mechanisms and CO₂ signaling mutants. In addition, models of Ca²⁺-dependent and Ca²⁺-independent signaling in guard cells have been developed and a new hypothesis has been formed in which physiological stimuli are proposed to prime Ca²⁺ sensors, thus enabling specificity in Ca²⁺-dependent signal transduction.

HT1 kinase controls stomatal movements

 

Arabidopsis HT1 kinase controls stomatal movements in response to CO2.

by Hashimoto-Sugimoto M., Negi J., Young J., Israelsson M., Schroeder J. I., Iba K. (2006)

in Nature Cell Biology 8,391–397. –

CrossRefMedlineWeb of Science

http://www.ncbi.nlm.nih.gov/pubmed/16518390?dopt=Abstract

Abstract

Guard cells, which form stomata in leaf epidermes, sense a multitude of environmental signals and integrate this information to regulate stomatal movements. Compared with the advanced understanding of light and water stress responses in guard cells, the molecular mechanisms that underlie stomatal CO(2) signalling have remained relatively obscure.

With a high-throughput leaf thermal imaging CO(2) screen, we report the isolation of two allelic Arabidopsis mutants (high leaf temperature 1; ht1-1 and ht1-2) that are altered in their ability to control stomatal movements in response to CO(2).

The strong allele, ht1-2, exhibits a markedly impaired CO(2) response but shows functional responses to blue light, fusicoccin and abscisic acid (ABA), indicating a role for HT1 in stomatal CO(2) signalling.

HT1 encodes a protein kinase that is expressed mainly in guard cells. Phosphorylation assays demonstrate that the activity of the HT1 protein carrying the ht1-1 or ht1-2 mutation is greatly impaired or abolished, respectively. Furthermore, dominant-negative HT1(K113W) transgenic plants, which lack HT1 kinase activity, show a disrupted CO(2) response.

These findings indicate that the HT1 kinase is important for regulation of stomatal movements and its function is more pronounced in response to CO(2) than it is to ABA or light.

HT1, a critical regulator for CO2 signaling and involved in stomatal opening

Photo credit: JXB

Fig. 5.

Stereo view of a structural model of HT1 kinase. The substituted and the deleted amino acid positions in the ht1 mutants are shown as stick residues and yellow ribbons, respectively. The docked substrate analogue, AMP-PNP, is shown as a ball-and-stick model. Lys 113 is an invariant catalytic lysine in subdomain II of protein kinases that is crucial for binding to ATP.

Dominant and recessive mutations in the Raf-like kinase HT1 gene completely disrupt stomatal responses to CO₂ in Arabidopsis

by Hashimoto-Sugimoto M., Negi J., Monda K., Higaki T., Isogai Y., Nakano T., Hasezawa S., Iba K. (2016)

in J. Exp. Bot. (2016)doi: 10.1093/jxb/erw134 – 

http://jxb.oxfordjournals.org/content/early/2016/03/30/jxb.erw134.full 

Abstract

HT1 (HIGH LEAF TEMPERATURE 1) is the first component associated with changes in stomatal aperture in response to CO₂ to be isolated by forward genetic screening.

The HT1 gene encodes a protein kinase expressed mainly in guard cells. The loss-of-function ht1-1 and ht1-2 mutants in Arabidopsis thaliana have CO₂-hypersensitive stomatal closure with concomitant reductions in their kinase activities in vitro.

In addition to these mutants, in this study we isolate or obtaine five new ht1 alleles (ht1-3, ht1-4, ht1-5, ht1-6, and ht1-7). Among the mutants, only ht1-3 has a dominant mutant phenotype and has widely opened stomata due to CO₂insensitivity. The ht1-3 mutant has a missense mutation affecting a non-conserved residue (R102K), whereas the other six recessive mutants have mutations in highly conserved residues in the catalytic domains required for kinase activity.

We found that the dominant mutation does not affect the expression of HT1 or the ability to phosphorylate casein, a universal kinase substrate, but it does affect autophosphorylation activity in vitro.

A 3D structural model of HT1 also shows that the R102 residue protrudes from the surface of the kinase, implying a role for the formation of oligomers and/or interaction with its targets.

We demonstrate that both the loss-of-function and gain-of-function ht1 mutants have completely disrupted CO₂ responses, although they have normal responses to ABA. Furthermore, light-induced stomatal opening is smaller in ht1-3 and much smaller in ht1-2.

Taken together, these results indicate that HT1 is a critical regulator for CO₂ signaling and is partially involved in the light-induced stomatal opening pathway.

A Munc13-like protein and stomatal responses

 

 

A Munc13-like protein in Arabidopsis mediates H⁺-ATPase translocation that is essential for stomatal responses

by Hashimoto-Sugimoto M., Higaki T., Yaeno T., Nagami A., Irie M., Fujimi M., Miyamoto M., Akita K., Negi J., Shirasu K., Hasezawa H., Iba K. (2013)

in Nature Communications4,Article number:2215 – doi:10.1038/ncomms3215 –

http://www.nature.com/ncomms/2013/130730/ncomms3215/full/ncomms3215.html

(a,b) Endosomal localization of GFP–PATROL1. Images of GFP–PATROL1 (green) and FM4-64 (red) in hypocotyl epidermal cells. The yellow square in (a) shows the part of the image that is enlarged in (b). Scale bars indicate 20 μm in (a) and 2 μm in (b). (c,d) GFP–PATROL1 localization changes in response to irradiation. Data are means±s.e.m. of four to seven independent guard cells. (e,f) GFP–PATROL1 localization changes in response to drought stress after leaf detachment. Data are means±s.e.m. of three independent guard cells. Asterisks indicate statistical significance (*P<0.05) as determined by Welch’s t-test. Scale bars=5 μm in (c) and (e). – http://www.nature.com/ncomms/2013/130730/ncomms3215/images/ncomms3215-f2.jpg

Abstract

Plants control CO₂ uptake and water loss by modulating the aperture of stomata located in the epidermis.

Stomatal opening is initiated by the activation of H⁺-ATPases in the guard-cell plasma membrane. In contrast to regulation of H⁺-ATPase activity, little is known about the translocation of the guard cell H⁺-ATPase to the plasma membrane.

Here we describe the isolation of an Arabidopsis gene, PATROL1, that controls the translocation of a major H⁺-ATPase, AHA1, to the plasma membrane. PATROL1 encodes a protein with a MUN domain, known to mediate synaptic priming in neuronal exocytosis in animals.

Environmental stimuli change the localization of plasma membrane-associated PATROL1 to an intracellular compartment. Plasma membrane localization of AHA1 and stomatal opening require the association of PATROL1 with AHA1. Increased stomatal opening responses in plants overexpressing PATROL1 enhance the CO₂assimilation rate, promoting plant growth.

The biology of stomatal guard cells

 

 

New approaches to the biology of stomatal guard cells.

by Negi J., Hashimoto-Sugimoto M., Kusumi K., Iba K. (2014)

in Plant Cell Physiol (2014) 55 (2):241-250.

doi: 10.1093/pcp/pct145

First published online: October 7, 2013 

This article appears in: Special Focus Issue Plant Response to CO₂

Abstract/FREE Full Text

Abstract

CO₂ acts as an environmental signal that regulates stomatal movements. High CO₂ concentrations reduce stomatal aperture, whereas low concentrations trigger stomatal opening.

In contrast to our advanced understanding of light and drought stress responses in guard cells, the molecular mechanisms underlying stomatal CO₂ sensing and signaling are largely unknown.

Leaf temperature provides a convenient indicator of transpiration, and can be used to detect mutants with altered stomatal control. To identify genes that function in CO₂ responses in guard cells, CO₂-insensitive mutants were isolated through high-throughput leaf thermal imaging.

The isolated mutants are categorized into three groups according to their phenotypes: (i) impaired in stomatal opening under low CO₂ concentrations; (ii) impaired in stomatal closing under high CO₂concentrations; and (iii) impaired in stomatal development.

Characterization of these mutants has begun to yield insights into the mechanisms of stomatal CO₂ responses. In this review, we summarize the current status of the field and discuss future prospects.

Stomatal responses and a Munc13-like protein

 

A Munc13-like protein in Arabidopsis mediates H+-ATPase translocation that is essential for stomatal responses

by Hashimoto-Sugimoto M., Higaki T., Yaeno T., Nagami A., Irie M., Fujimi M., Miyamoto M., Akita K., Negi J., Shirasu K., Hasezawa S. Iba K. (2013)

in Nature Communications 4: 2215. – 

http://www.nature.com/ncomms/2013/130730/ncomms3215/full/ncomms3215.html

(a) Three-week-old plants were subjected to the indicated [CO2]. The subtractive images show changes in leaf temperature in response to the transfer from high to low [CO2]. (b) CO2 response of stomatal aperture in WT, patrol1 mutants and 35S:GFP–PATROL1. Three-week-old plants were incubated at the indicated [CO2]. Data are means±s.e.m. (n=60) of three independent experiments. (c) Structure of the PATROL1 gene. PATROL1 consists of 27 exons (white boxes); black boxes highlight the 5′ and 3′ untranslated regions, respectively. Arrows indicate regions used in RT-PCR (Supplementary Figs S2, S4). (d) PATROL1 encodes a protein of unknown function with a MUN domain. DUF810 (IPR008528; 194–865 aa), MUN (428–1042 aa). (e) Phylogenetic relationships based on amino-acid sequence similarities between MUN domain-containing proteins and the MUN domains of Unc13/Munc13 proteins (UNC13-MUN (Ce: C. elegans), Munc13-1 MUN (Mm: Mus musculus)), as determined with CLUSTAL X. At, Arabidopsis thaliana; Rc, Ricinus communis; Vv, Vitis vinifera; Osj, Oryza sativa subsp.japonica; Sb, Sorghum bicolor; Pt, Populus trichocarpa. – http://www.nature.com/ncomms/2013/130730/ncomms3215/images/ncomms3215-f1.jpg

Abstract

Plants control CO₂ uptake and water loss by modulating the aperture of stomata located in the epidermis.

Stomatal opening is initiated by the activation of H⁺-ATPases in the guard-cell plasma membrane. In contrast to regulation of H⁺-ATPase activity, little is known about the translocation of the guard cell H⁺-ATPase to the plasma membrane.

Here we describe the isolation of an Arabidopsis gene, PATROL1, that controls the translocation of a major H⁺-ATPase, AHA1, to the plasma membrane. PATROL1 encodes a protein with a MUN domain, known to mediate synaptic priming in neuronal exocytosis in animals.

Environmental stimuli change the localization of plasma membrane-associated PATROL1 to an intracellular compartment. Plasma membrane localization of AHA1 and stomatal opening require the association of PATROL1 with AHA1. Increased stomatal opening responses in plants overexpressing PATROL1 enhance the CO₂assimilation rate, promoting plant growth.

CO2 Regulation of Stomatal Conductance

CO₂ Sensing and CO₂ Regulation of Stomatal Conductance: Advances and Open Questions

by Engineer C. B., Hashimoto-Sugimoto M., Negi J., Israelsson-Nordström M., Azoulay-Shemer T., Rappel W.-J., Iba K., Schroeder J. I. (2015)

in Trends in Plant Science: In Press Corrected Proof,

DOI: http://dx.doi.org/10.1016/j.tplants.2015.08.014

Summary

Guard cells form epidermal stomatal gas-exchange valves in plants and regulate the aperture of stomatal pores in response to changes in the carbon dioxide (CO₂) concentration ([CO₂]) in leaves.

Moreover, the development of stomata is repressed by elevated CO₂ in diverse plant species. Evidence suggests that plants can sense [CO₂] changes via guard cells and via mesophyll tissues in mediating stomatal movements.

We review new discoveries and open questions on mechanisms mediating CO₂-regulated stomatal movements and CO₂ modulation of stomatal development, which together function in the CO₂ regulation of stomatal conductance and gas exchange in plants.

Research in this area is timely in light of the necessity of selecting and developing crop cultivars that perform better in a shifting climate.

See the text: Trends in Plant Science

Stomatal Responses to Environmental Changes

Photo credit: PLOS One

Fig 1. Stomatal conductance in Arabidopsisecotypes that have demonstrated a low CO₂responsiveness.

Natural Variation in Stomatal Responses to Environmental Changes among Arabidopsis thaliana Ecotypes

by Takahashi S., Monda K., Negi J., Konishi F., Ishikawa S., Hashimoto-Sugimoto M., Goto N., Iba K. (2015)

in PLoS ONE 10(2): e0117449. –

doi:10.1371/journal.pone.0117449

(http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117449)

Abstract

Stomata are small pores surrounded by guard cells that regulate gas exchange between plants and the atmosphere. Guard cells integrate multiple environmental signals and control the aperture width to ensure appropriate stomatal function for plant survival. Leaf temperature can be used as an indirect indicator of stomatal conductance to environmental signals.

In this study, leaf thermal imaging of 374 Arabidopsis ecotypes was performed to assess their stomatal responses to changes in environmental CO2 concentrations.

We identified three ecotypes, Köln (Kl-4), Gabelstein (Ga-0), and Chisdra (Chi-1), that have particularly low responsiveness to changes in CO2 concentrations. We next investigated stomatal responses to other environmental signals in these selected ecotypes, with Col-0 as the reference.

The stomatal responses to light were also reduced in the three selected ecotypes when compared with Col-0. In contrast, their stomatal responses to changes in humidity were similar to those of Col-0. Of note, the responses to abscisic acid, a plant hormone involved in the adaptation of plants to reduced water availability, were not entirely consistent with the responses to humidity.

This study demonstrates that the stomatal responses to CO2 and light share closely associated signaling mechanisms that are not generally correlated with humidity signaling pathways in these ecotypes. The results might reflect differences between ecotypes in intrinsic response mechanisms to environmental signals.

Read the full article: PLOS one

Biology of Stomatal Guard Cells

 

New Approaches to the Biology of Stomatal Guard Cells

by Negi J., Hashimoto-Sugimoto M., Kusumi K., Iba K. (2014)

in Plant Cell Physiol 55: 241–250

CO2 acts as an environmental signal that regulates stomatal movements. High CO2 concentrations reduce stomatal aperture, whereas low concentrations trigger stomatal opening. In contrast to our advanced understanding of light and drought stress responses in guard cells, the molecular mechanisms underlying stomatal CO2 sensing and signaling are largely unknown.

Leaf temperature provides a convenient indicator of transpiration, and can be used to detect mutants with altered stomatal control. To identify genes that function in CO2 responses in guard cells, CO2-insensitive mutants were isolated through high-throughput leaf thermal imaging.

The isolated mutants are categorized into three groups according to their phenotypes: (i) impaired in stomatal opening under low CO2 concentrations; (ii) impaired in stomatal closing under high CO2 concentrations; and (iii) impaired in stomatal development.

Characterization of these mutants has begun to yield insights into the mechanisms of stomatal CO2 responses. In this review, we summarize the current status of the field and discuss future prospects.

Read the full article: PCP