The root is the below-ground organ of a plant, and it has evolved multiple signaling pathways that allow adaptation of architecture, growth rate, and direction to an ever-changing environment. Roots grow along the gravitropic vector towards beneficial areas in the soil to provide the plant with proper nutrients to ensure its survival and productivity. In addition, roots have developed escape mechanisms to avoid adverse environments, which include direct illumination. Standard laboratory growth conditions for basic research of plant development and stress adaptation include growing seedlings in Petri dishes on medium with roots exposed to light. Several studies have shown that direct illumination of roots alters their morphology, cellular and biochemical responses, which results in reduced nutrient uptake and adaptability upon additive stress stimuli. In this review, we summarize recent methods that allow the study of shaded roots under controlled laboratory conditions and discuss the observed changes in the results depending on the root illumination status.

• MeSH
• fyziologická adaptace * MeSH
• kořeny rostlin metabolismus   účinky záření   MeSH
• regulace genové exprese u rostlin účinky záření   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• rostliny metabolismus   účinky záření   MeSH
• semenáček metabolismus   účinky záření   MeSH
• světlo * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Studying stress pathways on the level of secondary metabolites that are found in very small concentration in the cells is complicated. In the algae, the role of individual metabolites (such as carotenoids, phenolic compounds, organic acids, and vitamins) and miRNAs that participate in plant's defence are very poorly understood during stressful conditions. Therefore, in the present experiment, the model organism Chlamydomonas reinhardtii was exposed to stress conditions (Lyc and UV-C irradiation) to detect these substances, even at very low concentrations. The purpose was to monitored changes at each response level with a future view to identifying their specific roles under different stress factors. In stress-treated cultures, numerous transcriptomic and metabolomic pathways were triggered in C. reinhardtii. Although Lyc significantly decreased the concentration of AA, suggesting that Lyc has a similar function in C. reinhardtii as in plants. The negative effect of UV-C radiation was based on the production of ROS and enhancement of antioxidant responses, resulting in increased levels of polyphenols and simple phenolic compounds. Both treatments did lead to extensive changes in transcript levels and miRNA expression patterns.

• MeSH
• alkaloidy amarylkovitých farmakologie   MeSH
• Chlamydomonas reinhardtii účinky léků   genetika   metabolismus   účinky záření   MeSH
• fenantridiny farmakologie   MeSH
• mikro RNA * MeSH
• polyfenoly metabolismus   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• RNA rostlin * MeSH
• ultrafialové záření * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Singlet oxygen produced from triplet excited chlorophylls in photosynthesis is a signal molecule that can induce programmed cell death (PCD) through the action of the OXIDATIVE STRESS INDUCIBLE 1 (OXI1) kinase. Here, we identify two negative regulators of light-induced PCD that modulate OXI1 expression: DAD1 and DAD2, homologs of the human antiapoptotic protein DEFENDER AGAINST CELL DEATH. Overexpressing OXI1 in Arabidopsis (Arabidopsis thaliana) increased plant sensitivity to high light and induced early senescence of mature leaves. Both phenomena rely on a marked accumulation of jasmonate and salicylate. DAD1 or DAD2 overexpression decreased OXI1 expression, jasmonate levels, and sensitivity to photooxidative stress. Knock-out mutants of DAD1 or DAD2 exhibited the opposite responses. Exogenous applications of jasmonate upregulated salicylate biosynthesis genes and caused leaf damage in wild-type plants but not in the salicylate biosynthesis mutant Salicylic acid induction-deficient2, indicating that salicylate plays a crucial role in PCD downstream of jasmonate. Treating plants with salicylate upregulated the DAD genes and downregulated OXI1 We conclude that OXI1 and DAD are antagonistic regulators of cell death through modulating jasmonate and salicylate levels. High light-induced PCD thus results from a tight control of the relative activities of these regulating proteins, with DAD exerting a negative feedback control on OXI1 expression.

• MeSH
• apoptóza genetika   účinky záření   MeSH
• Arabidopsis cytologie   genetika   metabolismus   MeSH
• biosyntetické dráhy účinky léků   genetika   účinky záření   MeSH
• cyklopentany metabolismus   farmakologie   MeSH
• fosfolipasy A1 genetika   metabolismus   MeSH
• kyselina salicylová metabolismus   farmakologie   MeSH
• listy rostlin cytologie   genetika   metabolismus   MeSH
• mutace MeSH
• oxylipiny metabolismus   farmakologie   MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• singletový kyslík metabolismus   MeSH
• stanovení celkové genové exprese metody   MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

In plants, the multistep phosphorelay (MSP) pathway mediates a range of regulatory processes, including those activated by cytokinins. The cross talk between cytokinin response and light has been known for a long time. However, the molecular mechanism underlying the interaction between light and cytokinin signaling remains elusive. In the screen for upstream regulators we identified a LONG PALE HYPOCOTYL (LPH) gene whose activity is indispensable for spatiotemporally correct expression of CYTOKININ INDEPENDENT1 (CKI1), encoding the constitutively active sensor His kinase that activates MSP signaling. lph is a new allele of HEME OXYGENASE1 (HY1) that encodes the key protein in the biosynthesis of phytochromobilin, a cofactor of photoconvertible phytochromes. Our analysis confirmed the light-dependent regulation of the CKI1 expression pattern. We show that CKI1 expression is under the control of phytochrome A (phyA), functioning as a dual (both positive and negative) regulator of CKI1 expression, presumably via the phyA-regulated transcription factors (TF) PHYTOCHROME INTERACTING FACTOR3 and CIRCADIAN CLOCK ASSOCIATED1. Changes in CKI1 expression observed in lph/hy1-7 and phy mutants correlate with misregulation of MSP signaling, changed cytokinin sensitivity, and developmental aberrations that were previously shown to be associated with cytokinin and/or CKI1 action. Besides that, we demonstrate a novel role of phyA-dependent CKI1 expression in the hypocotyl elongation and hook development during skotomorphogenesis. Based on these results, we propose that the light-dependent regulation of CKI1 provides a plausible mechanistic link underlying the well-known interaction between light- and cytokinin-controlled plant development.

• MeSH
• Arabidopsis genetika   metabolismus   účinky záření   MeSH
• cytokininy metabolismus   MeSH
• fytochrom A genetika   metabolismus   MeSH
• geneticky modifikované rostliny MeSH
• hemová oxygenasa (decyklizující) genetika   metabolismus   MeSH
• hypokotyl genetika   metabolismus   účinky záření   MeSH
• modely genetické MeSH
• mutace MeSH
• proteinkinasy genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin genetika   účinky záření   MeSH
• signální transdukce genetika   účinky záření   MeSH
• světlo * MeSH
• Publikační typ
• časopisecké články MeSH

Bud outgrowth is controlled by environmental and endogenous factors. Through the use of the photosynthesis inhibitor norflurazon and of masking experiments, evidence is given here that light acts mainly as a morphogenic signal in the triggering of bud outgrowth and that initial steps in the light signaling pathway involve cytokinins (CKs). Indeed, in rose (Rosa hybrida), inhibition of bud outgrowth by darkness is suppressed solely by the application of CKs. In contrast, application of sugars has a limited effect. Exposure of plants to white light (WL) induces a rapid (after 3-6 h of WL exposure) up-regulation of CK synthesis (RhIPT3 and RhIPT5), of CK activation (RhLOG8), and of CK putative transporter RhPUP5 genes and to the repression of the CK degradation RhCKX1 gene in the node. This leads to the accumulation of CKs in the node within 6 h and in the bud at 24 h and to the triggering of bud outgrowth. Molecular analysis of genes involved in major mechanisms of bud outgrowth (strigolactone signaling [RwMAX2], metabolism and transport of auxin [RhPIN1, RhYUC1, and RhTAR1], regulation of sugar sink strength [RhVI, RhSUSY, RhSUC2, and RhSWEET10], and cell division and expansion [RhEXP and RhPCNA]) reveal that, when supplied in darkness, CKs up-regulate their expression as rapidly and as intensely as WL Additionally, up-regulation of CKs by WL promotes xylem flux toward the bud, as evidenced by Methylene Blue accumulation in the bud after CK treatment in the dark. Altogether, these results suggest that CKs are initial components of the light signaling pathway that controls the initiation of bud outgrowth.

• MeSH
• biologické modely MeSH
• časové faktory MeSH
• cytokininy metabolismus   farmakologie   MeSH
• meristém genetika   růst a vývoj   metabolismus   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• Rosa genetika   růst a vývoj   metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• signální transdukce účinky léků   genetika   účinky záření   MeSH
• světlo * MeSH
• tma MeSH
• výhonky rostlin genetika   růst a vývoj   metabolismus   MeSH
• vývojová regulace genové exprese účinky léků   účinky záření   MeSH
• xylém genetika   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

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.

• 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

Cytokinins (CKs) regulate plant development and growth via a two-component signaling pathway. By forward genetic screening, we isolated an Arabidopsis mutant named grow fast on cytokinins 1 (gfc1), whose seedlings grew larger aerial parts on MS medium with CK. gfc1 is allelic to a previously reported cutin mutant defective in cuticular ridges (dcr). GFC1/DCR encodes a soluble BAHD acyltransferase (a name based on the first four enzymes characterized in this family: Benzylalcohol O-acetyltransferase, Anthocyanin O-hydroxycinnamoyltransferase, anthranilate N-hydroxycinnamoyl/benzoyltransferase and Deacetylvindoline 4-O-acetyltransferase) with diacylglycerol acyltransferase (DGAT) activity in vitro and is necessary for normal cuticle formation on epidermis in vivo. Here we show that gfc1 was a CK-insensitive mutant, as revealed by its low regeneration frequency in vitro and resistance to CK in adventitious root formation and dark-grown hypocotyl inhibition assays. In addition, gfc1 had de-etiolated phenotypes in darkness and was therefore defective in skotomorphogenesis. The background expression levels of most type-A Arabidopsis Response Regulator (ARR) genes were higher in the gfc1 mutant. The gfc1-associated phenotypes were also observed in the cutin-deficient glycerol-3-phosphate acyltransferase 4/8 (gpat4/8) double mutant [defective in glycerol-3-phosphate (G3P) acyltransferase enzymes GPAT4 and GPAT8, which redundantly catalyze the acylation of G3P by hydroxyl fatty acid (OH-FA)], but not in the cutin-deficient mutant cytochrome p450, family 86, subfamily A, polypeptide 2/aberrant induction of type three 1 (cyp86A2/att1), which affects the biosynthesis of some OH-FAs. Our results indicate that some acyltransferases associated with cutin formation are involved in CK responses and skotomorphogenesis in Arabidopsis.

• MeSH
• acyltransferasy genetika   metabolismus   MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   účinky záření   MeSH
• cytokininy metabolismus   farmakologie   MeSH
• fenotyp MeSH
• membránové lipidy biosyntéza   MeSH
• meristém účinky léků   genetika   růst a vývoj   účinky záření   MeSH
• morfogeneze * účinky léků   účinky záření   MeSH
• mutace MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• semenáček účinky léků   genetika   růst a vývoj   účinky záření   MeSH
• tma MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND AND AIMS: Nitric oxide (NO) is involved in the signalling and regulation of plant growth and development and responses to biotic and abiotic stresses. The photoperiod-sensitive mutant 7B-1 in tomato (Solanum lycopersicum) showing abscisic acid (ABA) overproduction and blue light (BL)-specific tolerance to osmotic stress represents a valuable model to study the interaction between light, hormones and stress signalling. The role of NO as a regulator of seed germination and ABA-dependent responses to osmotic stress was explored in wild-type and 7B-1 tomato under white light (WL) and BL. METHODS: Germination data were obtained from the incubation of seeds on germinating media of different composition. Histochemical analysis of NO production in germinating seeds was performed by fluorescence microscopy using a cell-permeable NO probe, and endogenous ABA was analysed by mass spectrometry. KEY RESULTS: The NO donor S-nitrosoglutathione stimulated seed germination, whereas the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) had an inhibitory effect. Under WL in both genotypes, PTIO strongly suppressed germination stimulated by fluridone, an ABA inhibitor. The stimulatory effect of the NO donor was also observed under osmotic stress for 7B-1 seeds under WL and BL. Seed germination inhibited by osmotic stress was restored by fluridone under WL, but less so under BL, in both genotypes. This effect of fluridone was further modulated by the NO donor and NO scavenger, but only to a minor extent. Fluorescence microscopy using the cell-permeable NO probe DAF-FM DA (4-amino-5-methylamino-2',7'-difluorofluorescein diacetate) revealed a higher level of NO in stressed 7B-1 compared with wild-type seeds. CONCLUSIONS: As well as defective BL signalling, the differential NO-dependent responses of the 7B-1 mutant are probably associated with its high endogenous ABA concentration and related impact on hormonal cross-talk in germinating seeds. These data confirm that light-controlled seed germination and stress responses include NO-dependent signalling.

• MeSH
• biologické modely MeSH
• cyklické N-oxidy farmakologie   MeSH
• donory oxidu dusnatého farmakologie   MeSH
• fluoresceiny analýza   MeSH
• fyziologický stres * účinky léků   účinky záření   MeSH
• imidazoly farmakologie   MeSH
• kinetika MeSH
• klíčení * účinky léků   účinky záření   MeSH
• kyselina abscisová metabolismus   MeSH
• mutace MeSH
• osmóza účinky léků   účinky záření   MeSH
• oxid dusnatý farmakologie   MeSH
• pyridony farmakologie   MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• S-nitrosoglutathion farmakologie   MeSH
• scavengery volných radikálů farmakologie   MeSH
• semena rostlinná účinky léků   genetika   fyziologie   účinky záření   MeSH
• signální transdukce účinky léků   účinky záření   MeSH
• Solanum lycopersicum účinky léků   genetika   fyziologie   účinky záření   MeSH
• světlo * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH