Abstract
The integration of conflicting signals in response to environmental constraints is essential to efficient plant growth and development. The light-dependent and the stress hormone abscisic acid (ABA)-dependent signaling pathways play opposite roles in many aspects of plant development. While these pathways have been extensively studied, the complex nature of their molecular dialogue is still obscure. When mobilized by the Arabidopsis thaliana β-glucosidase 1 (AtBG1), the glucose ester-conjugated inactive form of ABA has proven to be a source of the active hormone that is essential for the adaptation of the plant to water deficit, as evidenced by the impaired stomatal closure of atbg1 mutants in response to water stress. In a suppressor screen designed to identify the molecular components of AtBG1-associated physiological and developmental mechanisms, we identified the mutation variant of AtBG1 traits (vat1), a new mutant allele of the red light/far-red light photoreceptor PHYTOCHROME B (PHYB). Our study reveals that atbg1 plants harbor increased stomatal density in addition to impaired stomatal closure. We also provide evidence that the vat1/phyb mutation can restore the apparent transpiration of the atbg1 mutant by decreasing stomatal aperture and restoring a stomatal density similar to wild-type plants. Expression of key regulators of stomatal development showed a crosstalk between AtBG1-mediated ABA signaling and PHYB-mediated stomatal development. We conclude that the AtBG1-dependent regulation of ABA homeostasis and the PHYB-mediated light signaling pathways act antagonistically in the control of stomatal development.
Highlights
A particular change in a plant’s environment often has similar effects on both the development of the stomata and the stomatal aperture [1,2,3]
Our observation of increased stomatal density and index in atbg1 may be evidence that the impaired drought tolerance of the mutant in response to water stress is the consequence of an abnormally high number of stomata in addition to the previously reported impaired ability for stomata to properly close in response to water stress. These results indicate that the vat1 mutation restored stomatal density to levels similar to WT plants in atbg1/vat1(phyb) mutants, thereby establishing a relationship between PHYTOCHROME B (PHYB)-mediated light signaling, AtBG1dependent control of abscisic acid (ABA) homeostasis, and the regulation of stomatal development
The stomatal response of the vat1(phyb) single mutant was not significantly different than that of WT plants (Fig 4E). These results indicate that the improved drought tolerance of atbg1/vat1(phyb)
Summary
A particular change in a plant’s environment often has similar effects on both the development of the stomata and the stomatal aperture [1,2,3]. Red light exerts a positive influence on guard cell development and induces stomatal opening, in particular through activation of the photoreceptor PHYB [4,5,6,7]. Stomatal development in Arabidopsis thaliana begins when a protodermal cell differentiates via a multi-step process that produces three successive. ATBG1 and PHYB antagonistically regulate stomatal development. Santa Ana Botanic Garden SEM was acquired with a NSF Major Research Instrumentation grant NSF (Award #1626618).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
