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

The initiation of stomata, microscopic valves in the epidermis of higher plants that control of gas exchange, requires a co-ordinated sequence of asymmetric and symmetric divisions, which is under tight environmental and developmental control. Arabidopsis leaves grown under elevated photosynthetic photon flux density have a higher density of stomata. STOMAGEN encodes an epidermal patterning factor produced in the mesophyll, and our observations indicated that elevated photosynthetic irradiation stimulates STOMAGEN expression. Our analysis of gain and loss of function of STOMAGEN further detailed its function as a positive regulator of stomatal formation on both sides of the leaf, not only in terms of stomatal density across the leaf surface but also in terms of their stomatal index. STOMAGEN function was rate limiting for the light response of the stomatal lineage in the adaxial epidermis. Mutants in pathways that regulate stomatal spacing in the epidermis and have elevated stomatal density, such as stomatal density and distribution (sdd1) and too many mouth alleles, displayed elevated STOMAGEN expression, suggesting that STOMAGEN is either under the direct control of these pathways or is indirectly affected by stomatal patterning, suggestive of a feedback mechanism. These observations support a model in which changes in levels of light irradiation are perceived in the mesophyll and control the production of stomata in the epidermis by mesophyll-produced STOMAGEN, and whereby, conversely, stomatal patterning, either directly or indirectly, influences STOMAGEN levels.

• Klíčová slova
• Arabidopsis thaliana, PPFD, SDD1, STOMAGEN, TMM., stomatal density,
• MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   účinky záření   MeSH
• fotosyntéza MeSH
• listy rostlin růst a vývoj   metabolismus   účinky záření   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• průduchy rostlin genetika   růst a vývoj   metabolismus   účinky záření   MeSH
• regulace genové exprese u rostlin účinky záření   MeSH
• signální transdukce MeSH
• světlo MeSH
• vývojová regulace genové exprese účinky záření   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteiny huseníčku MeSH
• Stomagen protein, Arabidopsis MeSH Prohlížeč