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Summary The mesophyll provides a critical signal for stomatal responses to red light (RL) and CO2in angiosperms. By contrast, the stomatal response to blue light (BL) is largely guard cell‐specific. It is not known whether substomatal or mesophyll anatomy influences the effectiveness of the mesophyll signal driving stomatal responses to RL and CO2.Here we utilize the diverse substomatal anatomy in Restionaceae to investigate whether mesophyll anatomy has an influence on stomatal responses to light and CO2. Restionaceae from the subfamily Restionoideae have distinctive nonphotosynthetic, cuticle‐covered protective cells that line a large substomatal cavity, while most species from the subfamily Leptocarpoideae have a small substomatal cavity surrounded by mesophyll cells.We found that representative Restionoideae species do not have a stomatal response to RL or CO2, with only BL driving stomatal responses to light. By contrast, representative Leptocarpoideae species have a stomatal response to RL, BL and CO2.The absence of stomatal responses to RL and CO2in species with protective cells lining the substomatal cavity demonstrates the importance of mesophyll anatomy in stomatal control and suggests that the mesophyll signal that drives stomatal responses to RL and CO2requires close proximity of photosynthetic cells to the guard cells.
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Warming triggers stomatal opening by enhancement of photosynthesis and ensuing guard cell CO2 sensing, whereas higher temperatures induce a photosynthesis‐uncoupled response
Summary Plants integrate environmental stimuli to optimize photosynthesis vs water loss by controlling stomatal apertures. However, stomatal responses to temperature elevation and the underlying molecular genetic mechanisms remain less studied.We developed an approach for clamping leaf‐to‐air vapor pressure difference (VPDleaf) to fixed values, and recorded robust reversible warming‐induced stomatal opening in intact plants. We analyzed stomatal temperature responses of mutants impaired in guard cell signaling pathways for blue light, abscisic acid (ABA), CO2, and the temperature‐sensitive proteins, Phytochrome B (phyB) and EARLY‐FLOWERING‐3 (ELF3).We confirmed thatphot1‐5/phot2‐1leaves lacking blue‐light photoreceptors showed partially reduced warming‐induced stomatal opening. Furthermore, ABA‐biosynthesis, phyB, and ELF3 were not essential for the stomatal warming response. Strikingly,Arabidopsis(dicot) andBrachypodium distachyon(monocot) mutants lacking guard cell CO2sensors and signaling mechanisms, includinght1,mpk12/mpk4‐gc, andcbc1/cbc2abolished the stomatal warming response, suggesting a conserved mechanism across diverse plant lineages. Moreover, warming rapidly stimulated photosynthesis, resulting in a reduction in intercellular (CO2). Interestingly, further enhancing heat stress caused stomatal opening uncoupled from photosynthesis.We provide genetic and physiological evidence that the stomatal warming response is triggered by increased CO2assimilation and stomatal CO2sensing. Additionally, increasing heat stress functions via a distinct photosynthesis‐uncoupled stomatal opening pathway.
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- PAR ID:
- 10583777
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 244
- Issue:
- 5
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- 1847 to 1863
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/nph.20121
