The regulation of reactive oxygen species (ROS) levels in plants is ensured by mechanisms preventing their over accumulation, and by diverse antioxidants, including enzymes and nonenzymatic compounds. These are affected by redox conditions, posttranslational modifications, transcriptional and posttranscriptional modifications, Ca2+, nitric oxide (NO) and mitogen-activated protein kinase signaling pathways. Recent knowledge about protein-protein interactions (PPIs) of antioxidant enzymes advanced during last decade. The best-known examples are interactions mediated by redox buffering proteins such as thioredoxins and glutaredoxins. This review summarizes interactions of major antioxidant enzymes with regulatory and signaling proteins and their diverse functions. Such interactions are important for stability, degradation and activation of interacting partners. Moreover, PPIs of antioxidant enzymes may connect diverse metabolic processes with ROS scavenging. Proteins like receptor for activated C kinase 1 may ensure coordination of antioxidant enzymes to ensure efficient ROS regulation. Nevertheless, PPIs in antioxidant defense are understudied, and intensive research is required to define their role in complex regulation of ROS scavenging.

• Klíčová slova
• antioxidant enzymes, plants, protein-protein interactions, reactive oxygen species, receptor for activated C kinase 1, stress response,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

De novo shoot organogenesis (DNSO) is a procedure commonly used for the in vitro regeneration of shoots from a variety of plant tissues. Shoot regeneration occurs on nutrient media supplemented with the plant hormones cytokinin (CK) and auxin, which play essential roles in this process, and genes involved in their signaling cascades act as master regulators of the different phases of shoot regeneration. In the last 20 years, the genetic regulation of DNSO has been characterized in detail. However, as of today, the CK and auxin signaling events associated with shoot regeneration are often interpreted as a consequence of these hormones simply being present in the regeneration media, whereas the roles for their prior uptake and transport into the cultivated plant tissues are generally overlooked. Additionally, sucrose, commonly added to the regeneration media as a carbon source, plays a signaling role and has been recently shown to interact with CK and auxin and to affect the efficiency of shoot regeneration. In this review, we provide an integrative interpretation of the roles for CK and auxin in the process of DNSO, adding emphasis on their uptake from the regeneration media and their interaction with sucrose present in the media to their complex signaling outputs that mediate shoot regeneration.

• Klíčová slova
• DNSO, auxin, cytokinin, de novo shoot organogenesis, gene regulatory network, hormone uptake, shoot regeneration, sucrose, transport,
• MeSH
• cytokininy metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• organogeneze rostlin * MeSH
• regulátory růstu rostlin metabolismus   MeSH
• výhonky rostlin cytologie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• cytokininy MeSH
• kyseliny indoloctové MeSH
• regulátory růstu rostlin MeSH

Temperature passively affects biological processes involved in plant growth. Therefore, it is challenging to study the dedicated temperature signalling pathways that orchestrate thermomorphogenesis, a suite of elongation growth-based adaptations that enhance leaf-cooling capacity. We screened a chemical library for compounds that restored hypocotyl elongation in the pif4-2-deficient mutant background at warm temperature conditions in Arabidopsis thaliana to identify modulators of thermomorphogenesis. The small aromatic compound 'Heatin', containing 1-iminomethyl-2-naphthol as a pharmacophore, was selected as an enhancer of elongation growth. We show that ARABIDOPSIS ALDEHYDE OXIDASES redundantly contribute to Heatin-mediated hypocotyl elongation. Following a chemical proteomics approach, the members of the NITRILASE1-subfamily of auxin biosynthesis enzymes were identified among the molecular targets of Heatin. Our data reveal that nitrilases are involved in promotion of hypocotyl elongation in response to high temperature and Heatin-mediated hypocotyl elongation requires the NITRILASE1-subfamily members, NIT1 and NIT2. Heatin inhibits NIT1-subfamily enzymatic activity in vitro and the application of Heatin accordingly results in the accumulation of NIT1-subfamily substrate indole-3-acetonitrile in vivo. However, levels of the NIT1-subfamily product, bioactive auxin (indole-3-acetic acid), were also significantly increased. It is likely that the stimulation of hypocotyl elongation by Heatin might be independent of its observed interaction with NITRILASE1-subfamily members. However, nitrilases may contribute to the Heatin response by stimulating indole-3-acetic acid biosynthesis in an indirect way. Heatin and its functional analogues present novel chemical entities for studying auxin biology.

• Klíčová slova
• 1-iminomethyl-2-naphthol, Arabidopsis, Heatin, IAN, NIT1-subfamily, PIF4, aldehyde oxidase, chemical genetics, indole-3-acetonitrile, nitrilases, thermomorphogenesis,
• MeSH
• aldehydoxidasa genetika   metabolismus   MeSH
• aminohydrolasy genetika   metabolismus   MeSH
• apomorfin analogy a deriváty   farmakologie   MeSH
• Arabidopsis účinky léků   růst a vývoj   MeSH
• herbicidy farmakologie   MeSH
• hypokotyl účinky léků   růst a vývoj   MeSH
• inhibitory enzymů aplikace a dávkování   chemie   farmakologie   MeSH
• kyseliny indoloctové MeSH
• molekulární struktura MeSH
• pikloram farmakologie   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin účinky léků   MeSH
• transkriptom účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 10,11-dihydroxy-N-n-propylnorapomorphine MeSH Prohlížeč
• AAO1 protein, Arabidopsis MeSH Prohlížeč
• aldehydoxidasa MeSH
• aminohydrolasy MeSH
• apomorfin MeSH
• herbicidy MeSH
• inhibitory enzymů MeSH
• kyseliny indoloctové MeSH
• nitrilase MeSH Prohlížeč
• pikloram MeSH
• proteiny huseníčku MeSH

Damaged or unwanted cellular proteins are degraded by either autophagy or the ubiquitin/proteasome pathway. In Arabidopsis thaliana, sensing of D-glucose is achieved by the heterotrimeric G protein complex and regulator of G-protein signaling 1 (AtRGS1). Here, we showed that starvation increases proteasome-independent AtRGS1 degradation, and it is correlated with increased autophagic flux. RGS1 promoted the production of autophagosomes and autophagic flux; RGS1-yellow fluorescent protein (YFP) was surrounded by vacuolar dye FM4-64 (red fluorescence). RGS1 and autophagosomes co-localized in the root cells of Arabidopsis and BY-2 cells. We demonstrated that the autophagosome marker ATG8a interacts with AtRGS1 and its shorter form with truncation of the seven transmembrane and RGS1 domains in planta. Altogether, our data indicated the correlation of autophagosome formation with degradation and endocytosis of AtRGS1 through ATG8a.

• Klíčová slova
• Arabidopsis, BY-2, autophagy, glucose, nutrient starvation, regulator of G signaling protein 1,
• MeSH
• Arabidopsis MeSH
• autofagie MeSH
• autofagozomy metabolismus   MeSH
• endocytóza MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny RGS genetika   metabolismus   MeSH
• proteolýza MeSH
• rodina proteinů Atg8 genetika   metabolismus   MeSH
• signální transdukce MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ATG8 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• proteiny RGS MeSH
• RGS1 protein, Arabidopsis MeSH Prohlížeč
• rodina proteinů Atg8 MeSH

Plant cells use sugars mainly as a source or store of energy and carbon skeletons for anabolic reactions and for osmotic regulation. The perception of sugars and their responses are rather complex including the heterotrimeric G protein pathway and a seven-transmembrane RGS molecule. Previously, we found that endocytosis of the 7TM-RGS leads to sustained activation of the G protein pathway in the genetic model Arabidopsis. Here we show that other plants possess similar endocytosis systems of the 7TM-RGS proteins. A phosphorylation site essential for the endocytosis is well conserved in land plant 7TM-RGS proteins. In addition, conifer and tobacco 7TM-RGS proteins are internalized in response to sugar. These results indicate a universal mechanism to activate G signaling by endocytosis in plant cells that have 7TM-RGS proteins.

• Klíčová slova
• 7TM-RGS, Arabidopsis thaliana, Pinus taeda, endocytosis, sugar signaling, tobacco,
• MeSH
• Arabidopsis účinky léků   genetika   metabolismus   MeSH
• cévnaté rostliny účinky léků   genetika   metabolismus   MeSH
• endocytóza účinky léků   genetika   MeSH
• fosforylace účinky léků   genetika   MeSH
• glukosa farmakologie   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny RGS metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• tabák účinky léků   genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• glukosa MeSH
• proteiny huseníčku MeSH
• proteiny RGS MeSH
• rostlinné proteiny MeSH