The plant-specific receptor-like cytoplasmic kinases (RLCKs) form a large, poorly characterized family. Members of the RLCK VI_A class of dicots have a unique characteristic: their activity is regulated by Rho-of-plants (ROP) GTPases. The biological function of one of these kinases was investigated using a T-DNA insertion mutant and RNA interference. Loss of RLCK VI_A2 function resulted in restricted cell expansion and seedling growth. Although these phenotypes could be rescued by exogenous gibberellin, the mutant did not exhibit lower levels of active gibberellins nor decreased gibberellin sensitivity. Transcriptome analysis confirmed that gibberellin is not the direct target of the kinase; its absence rather affected the metabolism and signalling of other hormones such as auxin. It is hypothesized that gibberellins and the RLCK VI_A2 kinase act in parallel to regulate cell expansion and plant growth. Gene expression studies also indicated that the kinase might have an overlapping role with the transcription factor circuit (PIF4-BZR1-ARF6) controlling skotomorphogenesis-related hypocotyl/cotyledon elongation. Furthermore, the transcriptomic changes revealed that the loss of RLCK VI_A2 function alters cellular processes that are associated with cell membranes, take place at the cell periphery or in the apoplast, and are related to cellular transport and/or cell wall reorganisation.
- MeSH
- Arabidopsis účinky léků enzymologie genetika růst a vývoj MeSH
- DNA bakterií genetika metabolismus MeSH
- DNA vazebné proteiny genetika metabolismus MeSH
- geneticky modifikované rostliny MeSH
- gibereliny metabolismus farmakologie MeSH
- hypokotyl účinky léků enzymologie genetika růst a vývoj MeSH
- inzerční mutageneze MeSH
- kotyledon účinky léků enzymologie genetika růst a vývoj MeSH
- kyseliny indoloctové metabolismus farmakologie MeSH
- protein-serin-threoninkinasy genetika metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulace genové exprese u rostlin * MeSH
- regulátory růstu rostlin farmakologie MeSH
- semenáček účinky léků enzymologie genetika růst a vývoj MeSH
- stanovení celkové genové exprese MeSH
- transkripční faktory bHLH genetika metabolismus MeSH
- transkripční faktory genetika metabolismus MeSH
- transkriptom MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
Plant cell morphogenesis involves concerted rearrangements of microtubules and actin microfilaments. We previously reported that FH1, the main Arabidopsis thaliana housekeeping Class I membrane-anchored formin, contributes to actin dynamics and microtubule stability in rhizodermis cells. Here we examine the effects of mutations affecting FH1 (At3g25500) on cell morphogenesis and above-ground organ development in seedlings, as well as on cytoskeletal organization and dynamics, using a combination of confocal and variable angle epifluorescence microscopy with a pharmacological approach. Homozygous fh1 mutants exhibited cotyledon epinasty and had larger cotyledon pavement cells with more pronounced lobes than the wild type. The pavement cell shape alterations were enhanced by expression of the fluorescent microtubule marker GFP-microtubule-associated protein 4 (MAP4). Mutant cotyledon pavement cells exhibited reduced density and increased stability of microfilament bundles, as well as enhanced dynamics of microtubules. Analogous results were also obtained upon treatments with the formin inhibitor SMIFH2 (small molecule inhibitor of formin homology 2 domains). Pavement cell shape in wild-type (wt) and fh1 plants in some situations exhibited a differential response towards anti-cytoskeletal drugs, especially the microtubule disruptor oryzalin. Our observations indicate that FH1 participates in the control of microtubule dynamics, possibly via its effects on actin, subsequently influencing cell morphogenesis and macroscopic organ development.
- MeSH
- aktiny metabolismus MeSH
- Arabidopsis cytologie účinky léků metabolismus MeSH
- biologické markery metabolismus MeSH
- biologické modely MeSH
- cytoskelet účinky léků metabolismus MeSH
- fluorescence MeSH
- klathrin metabolismus MeSH
- kotyledon účinky léků metabolismus MeSH
- membránové proteiny metabolismus MeSH
- mikrofilamenta účinky léků metabolismus MeSH
- mikrotubuly účinky léků metabolismus MeSH
- mutace genetika MeSH
- proteiny huseníčku metabolismus MeSH
- semenáček účinky léků růst a vývoj metabolismus MeSH
- thioketony farmakologie MeSH
- tvar buňky * účinky léků MeSH
- uracil analogy a deriváty farmakologie MeSH
- zelené fluorescenční proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
To achieve host colonization, successful pathogens need to overcome plant basal defences. For this, (hemi)biotrophic pathogens secrete effectors that interfere with a range of physiological processes of the host plant. AvrLm4-7 is one of the cloned effectors from the hemibiotrophic fungus Leptosphaeria maculans 'brassicaceae' infecting mainly oilseed rape (Brassica napus). Although its mode of action is still unknown, AvrLm4-7 is strongly involved in L. maculans virulence. Here, we investigated the effect of AvrLm4-7 on plant defence responses in a susceptible cultivar of B. napus. Using two isogenic L. maculans isolates differing in the presence of a functional AvrLm4-7 allele [absence ('a4a7') and presence ('A4A7') of the allele], the plant hormone concentrations, defence-related gene transcription and reactive oxygen species (ROS) accumulation were analysed in infected B. napus cotyledons. Various components of the plant immune system were affected. Infection with the 'A4A7' isolate caused suppression of salicylic acid- and ethylene-dependent signalling, the pathways regulating an effective defence against L. maculans infection. Furthermore, ROS accumulation was decreased in cotyledons infected with the 'A4A7' isolate. Treatment with an antioxidant agent, ascorbic acid, increased the aggressiveness of the 'a4a7' L. maculans isolate, but not that of the 'A4A7' isolate. Together, our results suggest that the increased aggressiveness of the 'A4A7' L. maculans isolate could be caused by defects in ROS-dependent defence and/or linked to suppressed SA and ET signalling. This is the first study to provide insights into the manipulation of B. napus defence responses by an effector of L. maculans.
- MeSH
- alely MeSH
- antioxidancia farmakologie MeSH
- Ascomycota účinky léků izolace a purifikace metabolismus MeSH
- Brassica napus účinky léků růst a vývoj metabolismus mikrobiologie MeSH
- chromatografie kapalinová MeSH
- cyklopentany metabolismus MeSH
- ethyleny metabolismus MeSH
- fungální proteiny metabolismus MeSH
- hmotnostní spektrometrie MeSH
- interakce hostitele a patogenu účinky léků MeSH
- kotyledon účinky léků metabolismus mikrobiologie MeSH
- kyselina abscisová metabolismus MeSH
- kyselina askorbová farmakologie MeSH
- kyselina salicylová metabolismus MeSH
- oxylipiny metabolismus MeSH
- peroxid vodíku metabolismus MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- regulátory růstu rostlin metabolismus MeSH
- signální transdukce * účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND AND AIMS: Stomatal density (SD) generally decreases with rising atmospheric CO2 concentration, Ca. However, SD is also affected by light, air humidity and drought, all under systemic signalling from older leaves. This makes our understanding of how Ca controls SD incomplete. This study tested the hypotheses that SD is affected by the internal CO2 concentration of the leaf, Ci, rather than Ca, and that cotyledons, as the first plant assimilation organs, lack the systemic signal. METHODS: Sunflower (Helianthus annuus), beech (Fagus sylvatica), arabidopsis (Arabidopsis thaliana) and garden cress (Lepidium sativum) were grown under contrasting environmental conditions that affected Ci while Ca was kept constant. The SD, pavement cell density (PCD) and stomatal index (SI) responses to Ci in cotyledons and the first leaves of garden cress were compared. (13)C abundance (δ(13)C) in leaf dry matter was used to estimate the effective Ci during leaf development. The SD was estimated from leaf imprints. KEY RESULTS: SD correlated negatively with Ci in leaves of all four species and under three different treatments (irradiance, abscisic acid and osmotic stress). PCD in arabidopsis and garden cress responded similarly, so that SI was largely unaffected. However, SD and PCD of cotyledons were insensitive to Ci, indicating an essential role for systemic signalling. CONCLUSIONS: It is proposed that Ci or a Ci-linked factor plays an important role in modulating SD and PCD during epidermis development and leaf expansion. The absence of a Ci-SD relationship in the cotyledons of garden cress indicates the key role of lower-insertion CO2 assimilation organs in signal perception and its long-distance transport.
- MeSH
- Arabidopsis cytologie účinky léků MeSH
- buk (rod) cytologie účinky léků MeSH
- dehydratace MeSH
- Helianthus cytologie účinky léků MeSH
- kotyledon účinky léků fyziologie MeSH
- Lepidium cytologie účinky léků MeSH
- oxid uhličitý farmakologie MeSH
- počet buněk MeSH
- průduchy rostlin cytologie účinky léků MeSH
- životní prostředí MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The aim of the present study was to evaluate the adenosine triphospate (ATP), glucose-6-phosphate (glu-6P) and reduced form of nicotinamide adenine dinucleotide phosphate (NAD(P)H) cellular levels during the proliferation and maturation phases of Abies alba Mill. somatic embryos. For a better understanding of the dynamics of these parameters during the proliferation cycle, four embryonic cell lines were tested. During the maturation period, three independent experiments were conducted, focused on the effects of PEG-4000 (5 or 10% (w/v)) and abscisic acid (16, 32 or 64 μM) applied together (Experiments A and B) or with addition of gibberellic acid (Experiment C) on the dynamics of bio-energetic molecules and on the mean number of cotyledonary somatic embryos. Our results demonstrated that the cellular levels of bio-energetic molecules strongly depended on the composition of maturation media. Generally, the higher the number of cotyledonary embryos produced, the higher the level of ATP observed after a 2-week maturation period. The cellular level of ATP, glu-6P and NAD(P)H increased, particularly after the transition from the proliferation to the maturation phase when the differentiation and growth of somatic embryos occurred.
- MeSH
- adenosin metabolismus MeSH
- adenosintrifosfát metabolismus MeSH
- gibereliny farmakologie MeSH
- glukosa-6-fosfát metabolismus MeSH
- jedle účinky léků růst a vývoj metabolismus MeSH
- klíčení * účinky léků MeSH
- kotyledon účinky léků růst a vývoj metabolismus MeSH
- kultivační média MeSH
- kyselina abscisová farmakologie MeSH
- NAD metabolismus MeSH
- NADP metabolismus MeSH
- polyethylenglykoly farmakologie MeSH
- regulátory růstu rostlin farmakologie MeSH
- semena rostlinná účinky léků růst a vývoj metabolismus MeSH
- somatická embryogeneze rostlin MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- draslíkové kanály aktivované vápníkem antagonisté a inhibitory fyziologie MeSH
- draslíkové kanály řízené napětím antagonisté a inhibitory fyziologie MeSH
- finanční podpora výzkumu jako téma MeSH
- kotyledon fyziologie účinky léků MeSH
- lidé MeSH
- placentární oběh fyziologie účinky léků MeSH
- vazokonstrikce MeSH
- Check Tag
- lidé MeSH
