CO2 response screen in grass Brachypodium reveals the key role of a MAP kinase in CO2-triggered stomatal closure.

Plants respond to increased CO2 concentrations through stomatal closure, which can contribute to increased water use efficiency. Grasses display faster stomatal responses than eudicots due to dumbbell-shaped guard cells flanked by subsidiary cells working in opposition. However, forward genetic screening for stomatal CO2 signal transduction mutants in grasses has yet to be reported.

Deep dive into CO2-dependent molecular mechanisms driving stomatal responses in plants.

Recent advances are revealing mechanisms mediating CO-regulated stomatal movements in Arabidopsis, stomatal architecture and stomatal movements in grasses, and the long-term impact of CO on growth.

A role for calcium-dependent protein kinases in differential CO - and ABA-controlled stomatal closing and low CO -induced stomatal opening in Arabidopsis.

Low concentrations of CO cause stomatal opening, whereas [CO ] elevation leads to stomatal closure. Classical studies have suggested a role for Ca and protein phosphorylation in CO -induced stomatal closing. Calcium-dependent protein kinases (CPKs) and calcineurin-B-like proteins (CBLs) can sense and translate cytosolic elevation of the second messenger Ca into specific phosphorylation events.

MAP3Kinase-dependent SnRK2-kinase activation is required for abscisic acid signal transduction and rapid osmotic stress response.

Abiotic stresses, including drought and salinity, trigger a complex osmotic-stress and abscisic acid (ABA) signal transduction network. The core ABA signalling components are snf1-related protein kinase2s (SnRK2s), which are activated by ABA-triggered inhibition of type-2C protein-phosphatases (PP2Cs). SnRK2 kinases are also activated by a rapid, largely unknown, ABA-independent osmotic-stress signalling pathway.

Intact leaf gas exchange provides a robust method for measuring the kinetics of stomatal conductance responses to abscisic acid and other small molecules in and grasses.

Background: Guard cells perceive external and internal stimuli and regulate stomatal conductance in plants. With the use of gas exchange analyzers, time-resolved stomatal conductance responses to light intensity, [CO] concentration and relative humidity changes can be measured. This is more difficult to achieve when measuring stomatal responses to small soluble molecules such as the plant hormone abscisic acid (ABA) or the bacterial peptide flagellin 22 (flg22), in particular when investigating mutants with response phenotypes.

Chemical genetic identification of a lectin receptor kinase that transduces immune responses and interferes with abscisic acid signaling.

Insight into how plants simultaneously cope with multiple stresses, for example, when challenged with biotic stress from pathogen infection and abiotic stress from drought, is important both for understanding evolutionary trade-offs and optimizing crop responses to these stresses. Mechanisms by which initial plant immune signaling antagonizes abscisic acid (ABA) signal transduction require further investigation. Using a chemical genetics approach, the small molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) has previously been identified due to its ability to suppress ABA signaling via plant immune signaling components.

A seed resource for screening functionally redundant genes and isolation of new mutants impaired in CO2 and ABA responses.

The identification of homologous genes with functional overlap in forward genetic screens is severely limited. Here, we report the generation of over 14000 artificial microRNA (amiRNA)-expressing plants that enable screens of the functionally redundant gene space in Arabidopsis. A protocol was developed for isolating robust and reproducible amiRNA mutants.

Mitogen-activated protein kinases MPK4 and MPK12 are key components mediating CO -induced stomatal movements.

Respiration in leaves and the continued elevation in the atmospheric CO concentration cause CO -mediated reduction in stomatal pore apertures. Several mutants have been isolated for which stomatal responses to both abscisic acid (ABA) and CO are simultaneously defective. However, there are only few mutations that impair the stomatal response to elevated CO , but not to ABA.

Erratum: Correction Notice: Evaluation of Root pH Change Through Gel Containing pH-sensitive Indicator Bromocresol Purple.

[This corrects the article .].

Evaluation of Root pH Change Through Gel Containing pH-sensitive Indicator Bromocresol Purple.

The Rapid Alkalinization Factor (RALF) is a plant hormone peptide that inhibits proton transport causing alkalinization of the extracellular media. To detect the alkalinization response elicited by RALF peptides in root cells, seedlings are carefully transferred to a gel containing the pH-sensitive indicator bromocresol purple, treated with the peptide and photographed after 30 min. Herein the protocol is optimized for evaluation of exogenous treatment, described in detail and expected results are presented.

rapid alkalinization factor 1-mediated root growth inhibition is dependent on calmodulin-like protein 38.

rapid alkalinization factor 1 (AtRALF1) is a small secreted peptide hormone that inhibits root growth by repressing cell expansion. Although it is known that AtRALF1 binds the plasma membrane receptor FERONIA and conveys its signals via phosphorylation, the AtRALF1 signaling pathway is largely unknown. Here, using a yeast two-hybrid system to search for AtRALF1-interacting proteins in , we identified calmodulin-like protein 38 (CML38) as an AtRALF1-interacting partner.

BAK1 is involved in AtRALF1-induced inhibition of root cell expansion.

The rapid alkalinization factor (RALF) peptide negatively regulates cell expansion, and an antagonistic relationship has been demonstrated between AtRALF1, a root-specific RALF isoform in Arabidopsis, and brassinosteroids (BRs). An evaluation of the response of BR signaling mutants to AtRALF1 revealed that BRI1-associated receptor kinase1 (bak1) mutants are insensitive to AtRALF1 root growth inhibition activity. BAK1 was essential for the induction of AtRALF1-responsive genes but showed no effect on the mobilization of Ca2+ and alkalinization responses.

Arabidopsis thaliana RALF1 opposes brassinosteroid effects on root cell elongation and lateral root formation.

Rapid alkalinization factor (RALF) is a peptide signal that plays a basic role in cell biology and most likely regulates cell expansion. In this study, transgenic Arabidopsis thaliana lines with high and low levels of AtRALF1 transcripts were used to investigate this peptide's mechanism of action. Overexpression of the root-specific isoform AtRALF1 resulted in reduced cell size.

Biological activity of nine recombinant AtRALF peptides: implications for their perception and function in Arabidopsis.

RALF is a small (5 kDa) and ubiquitous plant peptide signal. It was first isolated from tobacco leaf protein extracts owing to its capacity to alkalinize the extracellular media of cell suspensions. RALFs inhibit root growth and hypocotyl elongation, and a role for RALFs in cell expansion has also been proposed.