Stomatal ontogenesis, patterning, and function are hallmarks of environmental plant adaptation, especially to conditions limiting plant growth, such as elevated temperatures and reduced water availability. The specification and distribution of a stomatal cell lineage and its terminal differentiation into guard cells require a master regulatory protein phosphorylation cascade involving the YODA mitogen-activated protein kinase kinase kinase. YODA signaling results in the activation of MITOGEN-ACTIVATED PROTEIN KINASEs (MPK3 and MPK6), which regulate transcription factors, including SPEECHLESS (SPCH). Here, we report that acute heat stress affects the phosphorylation and deactivation of SPCH and modulates stomatal density. By using complementary molecular, genetic, biochemical, and cell biology approaches, we provide solid evidence that HEAT SHOCK PROTEINS 90 (HSP90s) play a crucial role in transducing heat-stress response through the YODA cascade. Genetic studies revealed that YODA and HSP90.1 are epistatic, and they likely function linearly in the same developmental pathway regulating stomata formation. HSP90s interact with YODA, affect its cellular polarization, and modulate the phosphorylation of downstream targets, such as MPK6 and SPCH, under both normal and heat-stress conditions. Thus, HSP90-mediated specification and differentiation of the stomatal cell lineage couples stomatal development to environmental cues, providing an adaptive heat stress response mechanism in plants.

• Klíčová slova
• Arabidopsis, HSP90, MAPK, heat stress, stomata,
• MeSH
• Arabidopsis fyziologie   MeSH
• buněčná diferenciace MeSH
• buněčné dělení MeSH
• buněčný rodokmen MeSH
• epigeneze genetická MeSH
• fosforylace MeSH
• kotyledon cytologie   MeSH
• MAP kinasy kinas (kinas) genetika   metabolismus   MeSH
• mitogenem aktivované proteinkinasy kinas metabolismus   MeSH
• mitogenem aktivované proteinkinasy metabolismus   MeSH
• mutace MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny tepelného šoku HSP90 genetika   metabolismus   MeSH
• průduchy rostlin cytologie   růst a vývoj   metabolismus   MeSH
• reakce na tepelný šok * MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce MeSH
• transkripční faktory bHLH metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AtMPK3 protein, Arabidopsis MeSH Prohlížeč
• MAP kinasy kinas (kinas) MeSH
• mitogenem aktivované proteinkinasy kinas MeSH
• mitogenem aktivované proteinkinasy MeSH
• MPK6 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• proteiny tepelného šoku HSP90 MeSH
• SPEECHLESS protein, Arabidopsis MeSH Prohlížeč
• transkripční faktory bHLH MeSH
• YODA protein, Arabidopsis MeSH Prohlížeč

Stomatal development is tightly connected with the overall plant growth, while changes in environmental conditions, like elevated temperature, affect negatively stomatal formation. Stomatal ontogenesis follows a well-defined series of cell developmental transitions in the cotyledon and leaf epidermis that finally lead to the production of mature stomata. YODA signaling cascade regulates stomatal development mainly through the phosphorylation and inactivation of SPEECHLESS (SPCH) transcription factor, while HSP90 chaperones have a central role in the regulation of YODA cascade. Here, we report that acute heat stress affects negatively stomatal differentiation, leads to high phosphorylation levels of MPK3 and MPK6, and alters the expression of SPCH and MUTE transcription factors. Genetic depletion of HSP90 leads to decreased stomatal differentiation rates. Thus, HSP90 chaperones safeguard the completion of distinct stomatal differentiation steps depending on these two transcription factors under normal and heat stress conditions.

• Klíčová slova
• Stomata, differentiation, heat shock proteins 90, mitogen-activated protein kinases,
• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny tepelného šoku HSP90 metabolismus   MeSH
• průduchy rostlin metabolismus   MeSH
• reakce na tepelný šok fyziologie   MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce genetika   fyziologie   MeSH
• transkripční faktory bHLH genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• MUTE protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• proteiny tepelného šoku HSP90 MeSH
• SPEECHLESS protein, Arabidopsis MeSH Prohlížeč
• transkripční faktory bHLH MeSH