Guard cells count the number of unitary cytosolic Ca signals to regulate stomatal dynamics.

Transient stimulus-specific increases in the cytosolic Ca concentration ("calcium signatures") of guard cells have been proposed to regulate the opening and closure of stomatal pores on plant leaves. However, the mechanism by which these Ca signatures are generated and translated into stomatal movement is still largely unresolved. We used a light-gated, Ca-permeable variant of ChannelRhodopsin 2 (ChR2-XXM2.

Isolation and characterization of the gene HvFAR1 encoding acyl-CoA reductase from the cer-za.227 mutant of barley (Hordeum vulgare) and analysis of the cuticular barrier functions.

The cuticle is a protective layer covering aerial plant organs. We studied the function of waxes for the establishment of the cuticular barrier in barley (Hordeum vulgare). The barley eceriferum mutants cer-za.

Divergent evolutionary trajectories of bryophytes and tracheophytes from a complex common ancestor of land plants.

The origin of plants and their colonization of land fundamentally transformed the terrestrial environment. Here we elucidate the basis of this formative episode in Earth history through patterns of lineage, gene and genome evolution. We use new fossil calibrations, a relative clade age calibration (informed by horizontal gene transfer) and new phylogenomic methods for mapping gene family origins.

The Arabidopsis Rab protein RABC1 affects stomatal development by regulating lipid droplet dynamics.

Lipid droplets (LDs) are evolutionarily conserved organelles that serve as hubs of cellular lipid and energy metabolism in virtually all organisms. Mobilization of LDs is important in light-induced stomatal opening. However, whether and how LDs are involved in stomatal development remains unknown.

The origin and evolution of stomata.

The acquisition of stomata is one of the key innovations that led to the colonisation of the terrestrial environment by the earliest land plants. However, our understanding of the origin, evolution and the ancestral function of stomata is incomplete. Phylogenomic analyses indicate that, firstly, stomata are ancient structures, present in the common ancestor of land plants, prior to the divergence of bryophytes and tracheophytes and, secondly, there has been reductive stomatal evolution, especially in the bryophytes (with complete loss in the liverworts).

Countering elevated CO induced Fe and Zn reduction in Arabidopsis seeds.

Growth at increased concentrations of CO induces a reduction in seed zinc (Zn) and iron (Fe). Using Arabidopsis thaliana, we investigated whether this could be mitigated by reducing the elevated CO -induced decrease in transpiration. We used an infrared imaging-based screen to isolate mutants in At1g08080 that encodes ALPHA CARBONIC ANHYDRASE 7 (ACA7).

Conditional stomatal closure in a fern shares molecular features with flowering plant active stomatal responses.

Stomata evolved as plants transitioned from water to land, enabling carbon dioxide uptake and water loss to be controlled. In flowering plants, the most recently divergent land plant lineage, stomatal pores actively close in response to drought. In this response, the phytohormone abscisic acid (ABA) triggers signaling cascades that lead to ion and water loss in the guard cells of the stomatal complex, causing a reduction in turgor and pore closure.

ABA signalling and metabolism are not essential for dark-induced stomatal closure but affect response speed.

Stomata are microscopic pores that open and close, acting to balance CO uptake with water loss. Stomata close in response to various signals including the drought hormone abscisic acid (ABA), microbe-associated-molecular-patterns, high CO levels, and darkness. The signalling pathways underlying ABA-induced stomatal closure are well known, however, the mechanism for dark-induced stomatal closure is less clear.

Stomatal responses to carbon dioxide and light require abscisic acid catabolism in .

In plants, stomata control water loss and CO uptake. The aperture and density of stomatal pores, and hence the exchange of gases between the plant and the atmosphere, are controlled by internal factors such as the plant hormone abscisic acid (ABA) and external signals including light and CO. In this study, we examine the importance of ABA catabolism in the stomatal responses to CO and light.

ROS of Distinct Sources and Salicylic Acid Separate Elevated CO-Mediated Stomatal Movements in Arabidopsis.

Elevated CO (eCO) often reduces leaf stomatal aperture and density thus impacts plant physiology and productivity. We have previously demonstrated that the Arabidopsis BIG protein distinguishes between the processes of eCO-induced stomatal closure and eCO-inhibited stomatal opening. However, the mechanistic basis of this action is not fully understood.

Phylogenomic Evidence for the Monophyly of Bryophytes and the Reductive Evolution of Stomata.

The origin of land plants was accompanied by new adaptations to life on land, including the evolution of stomata-pores on the surface of plants that regulate gas exchange. The genes that underpin the development and function of stomata have been extensively studied in model angiosperms, such as Arabidopsis. However, little is known about stomata in bryophytes, and their evolutionary origins and ancestral function remain poorly understood.

The Circadian Clock Influences the Long-Term Water Use Efficiency of Arabidopsis.

In plants, water use efficiency (WUE) is a complex trait arising from numerous physiological and developmental characteristics. Here, we investigated the involvement of circadian regulation in long-term WUE in Arabidopsis () under light and dark conditions. Circadian rhythms are generated by the circadian oscillator, which provides a cellular measure of the time of day.

Guard Cells Integrate Light and Temperature Signals to Control Stomatal Aperture.

High temperature promotes guard cell expansion, which opens stomatal pores to facilitate leaf cooling. How the high-temperature signal is perceived and transmitted to regulate stomatal aperture is, however, unknown. Here, we used a reverse-genetics approach to understand high temperature-mediated stomatal opening in Arabidopsis ().

The role of Arabidopsis ABA receptors from the PYR/PYL/RCAR family in stomatal acclimation and closure signal integration.

Stomata are microscopic pores found on the surfaces of leaves that act to control CO uptake and water loss. By integrating information derived from endogenous signals with cues from the surrounding environment, the guard cells, which surround the pore, 'set' the stomatal aperture to suit the prevailing conditions. Much research has concentrated on understanding the rapid intracellular changes that result in immediate changes to the stomatal aperture.

Short- and Long-Term Effects of UVA on Arabidopsis Are Mediated by a Novel cGMP Phosphodiesterase.

Although UVA radiation (315-400 nm) represents 95% of the UV radiation reaching the earth's surface, surprisingly little is known about its effects on plants [1]. We show that in Arabidopsis, short-term exposure to UVA inhibits the opening of stomata, and this requires a reduction in the cytosolic level of cGMP. This process is independent of UVR8, the UVB receptor.

BIG regulates stomatal immunity and jasmonate production in Arabidopsis.

Plants have evolved an array of responses that provide them with protection from attack by microorganisms and other predators. Many of these mechanisms depend upon interactions between the plant hormones jasmonate (JA) and ethylene (ET). However, the molecular basis of these interactions is insufficiently understood.

How Arabidopsis Talks to Itself about Its Water Supply.

Takahashi et al. (2018) report that the peptide CLE25 together with the BAM1, BAM3 LRR receptor-like kinases are involved in root-to-shoot communication during dehydration stress in Arabidopsis.

A Tandem Amino Acid Residue Motif in Guard Cell SLAC1 Anion Channel of Grasses Allows for the Control of Stomatal Aperture by Nitrate.

The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution, leaf CO uptake and transpirational water loss were optimized by the acquisition of grass-specific stomatal complexes.

KIN7 Kinase Regulates the Vacuolar TPK1 K Channel during Stomatal Closure.

Stomata are leaf pores that regulate CO uptake and evapotranspirational water loss. By controlling CO uptake, stomata impact on photosynthesis and dry matter accumulation. The regulation of evapotranspiration is equally important because it impacts on nutrient accumulation and leaf cooling and enables the plant to limit water loss during drought [1].

The BIG protein distinguishes the process of CO -induced stomatal closure from the inhibition of stomatal opening by CO.

We conducted an infrared thermal imaging-based genetic screen to identify Arabidopsis mutants displaying aberrant stomatal behavior in response to elevated concentrations of CO . This approach resulted in the isolation of a novel allele of the Arabidopsis BIG locus (At3g02260) that we have called CO insensitive 1 (cis1). BIG mutants are compromised in elevated CO -induced stomatal closure and bicarbonate activation of S-type anion channel currents.

The Evolution of Calcium-Based Signalling in Plants.

The calcium-based intracellular signalling system is used ubiquitously to couple extracellular stimuli to their characteristic intracellular responses. It is becoming clear from genomic and physiological investigations that while the basic elements in the toolkit are common between plants and animals, evolution has acted in such a way that, in plants, some components have diversified with respect to their animal counterparts, while others have either been lost or have never evolved in the plant lineages. In comparison with animals, in plants there appears to have been a loss of diversity in calcium-influx mechanisms at the plasma membrane.