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
BACKGROUND: Nanoparticles (NPs) serve various industrial and household purposes, and their increasing use creates an environmental hazard because of their uncontrolled release into ecosystems. An important aspect of the risk assessment of NPs is to understand their interactions with plants. The aim of this study was to examine the effect of Au (10 and 20 ppm), Ag, and Pt (20 and 40 ppm) NPs on oakleaf lettuce, with particular emphasis on plant antioxidative mechanisms. Nanoparticles were applied once on the leaves of 2-week-old lettuce seedlings, after next week laboratory analyses were performed. RESULTS: The antioxidant potential of oakleaf lettuce seedlings sprayed with metal NPs at different concentrations was investigated. Chlorophylls, fresh and dry weight were also determined. Foliar exposure of the seedlings to metal NPs did not affect ascorbate peroxidase activity, total peroxidase activity increased after Au-NPs treatment, but decreased after applying Ag-NPs and Pt-NPs. Both concentrations of Au-NPs and Pt-NPs tested caused an increase in glutathione (GSH) content, while no NPs affected L-ascorbic acid content in the plants. Ag-NPs and Pt-NPs applied as 40 ppm solution increased total phenolics content by 17 and 15%, respectively, compared to the control. Carotenoids content increased when Ag-NPs and Au-NPs (20 and 40 ppm) and Pt-NPs (20 ppm) were applied. Plants treated with 40 ppm of Ag-NPs and Pt-NPs showed significantly higher total antioxidant capacity and higher concentration of chlorophyll a (only for Ag-NPs) than control. Pt-NPs applied as 40 ppm increased fresh weight and total dry weight of lettuce shoot. CONCLUSIONS: Results showed that the concentrations of NPs applied and various types of metal NPs had varying impact on the antioxidant status of oakleaf lettuce. Alteration of POX activity and in biosynthesis of glutathione, total phenolics, and carotenoids due to metal NPs showed that tested nanoparticles can act as stress stimuli. However, judging by the slight changes in chlorophyll concentrations and in the fresh and dry weight of the plants, and even based on the some increases in these traits after M-NPs treatment, the stress intensity was relatively low, and the plants were able to cope with its negative effects.
Being a chilling-sensitive staple crop, rice (Oryza sativa L.) is vulnerable to climate change. The competence of rice to withstand chilling stress should, therefore, be enhanced through technological tools. The present study employed chemical intervention like application of sodium nitroprusside (SNP) as nitric oxide (NO) donor and elucidated the underlying morpho-physiological and biochemical mechanisms of NO-mediated chilling tolerance in rice plants. At germination stage, germination indicators were interrupted by chilling stress (5.0 ± 1.0 °C for 8 h day-1), while pretreatment with 100 μM SNP markedly improved all the indicators. At seedling stage (14-day-old), chilling stress caused stunted growth with visible toxicity along with alteration of biochemical markers, for example, increase in oxidative stress markers (superoxide, hydrogen peroxide, and malondialdehyde) and osmolytes (total soluble sugar; proline and soluble protein content, SPC), and decrease in chlorophyll (Chl), relative water content (RWC), and antioxidants. However, NO application attenuated toxicity symptoms with improving growth attributes which might be related to enhance activities of antioxidants, mineral contents, Chl, RWC and SPC. Furthermore, principal component analysis indicated that water imbalance and increased oxidative damage were the main contributors to chilling injury, whereas NO-mediated mineral homeostasis and antioxidant defense were the critical determinants for chilling tolerance in rice. Collectively, our findings revealed that NO protects against chilling stress through valorizing cellular defense mechanisms, suggesting that exogenous application of NO could be a potential tool to evolve cold tolerance as well as climate resilience in rice.
- MeSH
- donory oxidu dusnatého farmakologie MeSH
- homeostáza účinky léků MeSH
- klíčení účinky léků MeSH
- malondialdehyd metabolismus MeSH
- nitroprusid farmakologie MeSH
- nízká teplota MeSH
- ochrana úrody metody MeSH
- oxid dusnatý metabolismus MeSH
- peroxid vodíku metabolismus MeSH
- peroxidace lipidů účinky léků MeSH
- peroxidasy metabolismus MeSH
- reakce na chladový šok fyziologie MeSH
- rýže (rod) účinky léků MeSH
- semenáček účinky léků MeSH
- superoxidy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We have recently discovered that brassinosteroids (BRs) can inhibit the growth of etiolated pea seedlings dose-dependently in a similar manner to the 'triple response' induced by ethylene. We demonstrate here that the growth inhibition of etiolated pea shoots strongly correlates with increases in ethylene production, which also responds dose-dependently to applied BRs. We assessed the biological activities of two natural BRs on pea seedlings, which are excellent material as they grow rapidly, and respond both linearly and uni-phasically to applied BRs. We then compared the BRs' inhibitory effects on growth, and induction of ethylene and ACC (1-aminocyclopropane-1-carboxylic acid) production, to those of representatives of other phytohormone classes (cytokinins, auxins, and gibberellins). Auxin induced ca. 50-fold weaker responses in etiolated pea seedlings than brassinolide, and the other phytohormones induced much weaker (or opposite) responses. Following the optimization of conditions for determining ethylene production after BR treatment, we found a positive correlation between BR bioactivity and ethylene production. Finally, we optimized conditions for pea growth responses and developed a new, highly sensitive, and convenient bioassay for BR activity.
- MeSH
- aminokyseliny cyklické metabolismus MeSH
- biotest metody MeSH
- brassinosteroidy farmakologie MeSH
- ethyleny metabolismus MeSH
- hrách setý účinky léků růst a vývoj metabolismus MeSH
- inhibitory růstu farmakologie MeSH
- kyseliny indoloctové farmakologie MeSH
- regulátory růstu rostlin farmakokinetika farmakologie MeSH
- semenáček účinky léků růst a vývoj metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A high degree of developmental plasticity enables plants to adapt to continuous, often unfavorable and unpredictable changes in their environment. At the molecular level, adaptive advantages for plants are primarily provided by epigenetic machinery including DNA methylation, histone modifications, and the activity of noncoding RNA molecules. Using a mass spectrometry-based proteomic approach, we examined the levels of acetylated histone peptide forms in Arabidopsis plants with a loss of function of histone deacetylase 6 (HDA6), and in plants germinated in the presence of HDA inhibitors trichostatin A (TSA) and sodium butyrate (NaB). Our analyses revealed particular lysine sites at histone sequences targeted by the HDA6 enzyme, and by TSA- and NaB-sensitive HDAs. Compared with plants exposed to drugs, more dramatic changes in the overall profiles of histone post-translational modifications were identified in hda6 mutants. However, loss of HDA6 was not sufficient by itself to induce hyperacetylation to the maximum degree, implying complementary activities of other HDAs. In contrast to hda6 mutants that did not exhibit any obvious phenotypic defects, the phenotypes of seedlings exposed to HDA inhibitors were markedly affected, showing that the effect of these drugs on early plant development is not limited to the modulation of histone acetylation levels.
- MeSH
- Arabidopsis genetika růst a vývoj MeSH
- histondeacetylasy genetika MeSH
- histonový kód účinky léků genetika MeSH
- inhibitory histondeacetylas farmakologie MeSH
- klíčení genetika MeSH
- kyselina máselná farmakologie MeSH
- kyseliny hydroxamové farmakologie MeSH
- metylace DNA účinky léků MeSH
- proteiny huseníčku antagonisté a inhibitory genetika MeSH
- proteomika * MeSH
- regulace genové exprese u rostlin MeSH
- semenáček účinky léků genetika MeSH
- umlčování genů MeSH
- vývoj rostlin účinky léků genetika MeSH
- Publikační typ
- časopisecké články MeSH
Although plants are often exposed to atmospheric nanoparticles (NPs), the mechanism of NP deposition and their effects on physiology and metabolism, and particularly in combination with other stressors, are not yet understood. Exploring interactions between stressors is particularly important for understanding plant responses in urban environments where elevated temperatures can be associated with air pollution. Accordingly, 3-year-old spruce seedlings were exposed for 2 weeks to aerial cadmium oxide (CdO) NPs of environmentally relevant size (8-62 nm) and concentration (2 × 105 cm-3). While half the seedlings were initially acclimated to high temperature (35 °C) and vapour pressure deficit (VPD; 2.81 kPa), the second half of the plants were left under non-stressed conditions (20 °C, 0.58 kPa). Atomic absorption spectrometry was used to determine Cd content in needles, while gas and liquid chromatography was used to determine changes in primary and secondary metabolites. Photosynthesis-related processes were explored with gas-exchange and chlorophyll fluorescence systems. Our work supports the hypothesis that atmospheric CdO NPs penetrate into leaves but high temperature and VPD reduce such penetration due to stomatal closure. The hypothesis that atmospheric CdO NPs influences physiological and metabolic processes in plants was also confirmed. This impact strengthens with increasing time of exposure. Finally, we found evidence that plants acclimated to stress conditions have different sensitivity to CdO NPs compared to plants not so acclimated. These findings have important consequences for understanding impacts of global warming on plants and indicates that although the effects of elevated temperatures can be deleterious, this may limit other forms of plant stress associated with air pollution.
- MeSH
- aklimatizace fyziologie MeSH
- borovice MeSH
- fotosyntéza fyziologie MeSH
- globální oteplování MeSH
- jedle MeSH
- látky znečišťující vzduch toxicita MeSH
- látky znečišťující životní prostředí metabolismus MeSH
- listy rostlin účinky léků MeSH
- nanočástice toxicita MeSH
- oxidy toxicita MeSH
- semenáček účinky léků MeSH
- sloučeniny kadmia toxicita MeSH
- smrk účinky léků fyziologie MeSH
- teplota * MeSH
- vysoká teplota MeSH
- Publikační typ
- časopisecké články MeSH
N-acetylcysteine (N-Acetyl L-cysteine, NAC) is a thiol compound derived from the addition of the acetyl group to cysteine amino acid. NAC has been used as an antioxidant, free radical scavenger, and chelating agent for reducing the deleterious effects on plants of biotic and abiotic environmental stresses. It can also relieve heavy metal (HM) toxicity, although its alleviating mechanism remains unknown. In this study, we compared HM-stressed (Cu, Hg, Cd and Pb, 100 μM each) wheat seedlings without NAC treatment and in combination with NAC (1 mM). In comparison to HMs alone, NAC treatment in combination with HMs (Cu, Cd, Hg and Pb, respectively) stimulated root growth (1.1-, 1.5-, 10.5- and 1.9-fold), and significantly increased fresh (1.3-, 1.5-, 4.3- and 1.4-fold) and dry (1.2-, 1.5-, 2.5- and 1.2-fold) mass. Combination treatment also led to significant reductions in HM concentrations (1.3-, 1.4-, 4- and 1.1-fold, respectively). GSH (1.1 - 1.8-fold), TBARS (1.4 - 2.7-fold) and H2O2 (1.6 - 1.8-fold) contents in treatment with HMs alone were significantly mitigated by the NAC combination. Some of the antioxidant enzyme activities increased or reduced by some HM treatments alone were stimulated by a combination of NAC with HMs, or remained unchanged or changed only insignificantly, supported by the phenolic pool of the plant. Ferulic, p-comaric and syringic acids were the major phenolic acids (PAs) in the roots in free, ester, glycoside and ester-bound forms, and their concentrations were increased by HM treatments alone, in comparison to the control seedlings, while PAs concentrations were relatively reduced by NAC in combination with HMs. These results indicate that NAC can alleviate HM toxicity and improve the growth of HM-stressed wheat seedlings by coordinated induction of the phenolic pool and the antioxidant defence system.
- MeSH
- acetylcystein farmakologie MeSH
- antioxidancia farmakologie MeSH
- hydroxybenzoáty metabolismus MeSH
- látky reagující s kyselinou thiobarbiturovou metabolismus MeSH
- látky znečišťující půdu toxicita MeSH
- oxidační stres účinky léků MeSH
- peroxid vodíku metabolismus MeSH
- pšenice účinky léků enzymologie růst a vývoj MeSH
- semenáček účinky léků enzymologie růst a vývoj MeSH
- těžké kovy toxicita MeSH
- Publikační typ
- časopisecké články MeSH
Uptake of water and nutrients by roots affects the ontogenesis of the whole plant. Nanoparticles, e.g. gold nanoparticles, have a broad range of applications in many fields which leads to the transfer of these materials into the environment. Thus, the understanding of their impact on the growth and development of the root system is an emerging issue. During our studies on the effect of positively charged gold nanoparticles on the barley roots, a hairless phenotype was found. We investigated whether this phenotype correlates with changes in symplasmic communication, which is an important factor that regulates, among others, differentiation of the rhizodermis into hair and non-hair cells. The results showed no restriction in symplasmic communication in the treated roots, in contrast to the control roots, in which the trichoblasts and atrichoblasts were symplasmically isolated during their differentiation. Moreover, differences concerning the root morphology, histology, ultrastructure and the cell wall composition were detected between the control and the treated roots. These findings suggest that the harmful effect of nanoparticles on plant growth may, among others, consist in disrupting the symplasmic communication/isolation, which leads to the development of a hairless root phenotype, thus limiting the functioning of the roots.
- MeSH
- buněčná diferenciace účinky léků MeSH
- buněčná membrána metabolismus MeSH
- epidermis rostlin cytologie účinky léků metabolismus MeSH
- ječmen (rod) účinky léků genetika růst a vývoj metabolismus MeSH
- kořeny rostlin cytologie účinky léků růst a vývoj metabolismus MeSH
- kovové nanočástice toxicita MeSH
- látky znečišťující půdu toxicita MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- semenáček účinky léků růst a vývoj MeSH
- voda metabolismus MeSH
- živiny metabolismus MeSH
- zlato toxicita MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This paper analyzes the effect of caesium (Cs) concentration on seed germination, seedling growth, root uptake, and leaf uptake of Lactuca sativa to understand the potential transfer of the metal from contaminated soil to humans through the food chain. The results of germination experiments show that seed germination and seedling growth strongly depend on increasing Cs concentration, with a decrease in the number of germinated seeds compared to the control up to 13.6% and a reduction in seedling growth up to 10.3% at the highest Cs tested concentration (15 mM). Uptake experiments indicate a low transfer of Cs from soil to leaves and roots of the plants, ranging between 0.06% and 2.2%. The transfer is found to be a not-monotone function of soil potassium (K) content, with highest values corresponding to 1-2 mM K2SO4. Increasing concentrations of K lead to lower translocation of Cs from roots to leaves. Values above the average amount applied (20 and 40 mM K2SO4) almost stop the translocation, suggesting the use of a high amount of K2SO4 protects the food chain from Cs contamination.
Systemin (SYS), an octadecapeptide hormone processed from a 200-amino-acid precursor (prosystemin, PS), plays a central role in the systemic activation of defense genes in tomato in response to herbivore and pathogen attacks. However, whether PS mRNA is transferable and its role in systemic defense responses remain unknown. We created the transgenic tomato PS gene tagged with the green fluorescent protein (PS-GFP) using a shoot- or root-specific promoter, and the constitutive 35S promoter in Arabidopsis. Subcellular localization of PS-/SYS-GFP was observed using confocal laser scanning microscopy and gene transcripts were determined using quantitative real-time PCR. In Arabidopsis, PS protein can be processed and SYS is secreted. Shoot-/root-specific expression of PS-GFP in Arabidopsis, and grafting experiments, revealed that the PS mRNA moves in a bi-directional manner. We also found that ectopic expression of PS improves Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea, consistent with substantial upregulation of the transcript levels of specific pathogen-responsive genes. Our results provide novel insights into the multifaceted mechanism of SYS signaling transport and its potential application in genetic engineering for increasing pathogen resistance across diverse plant families.
- MeSH
- Arabidopsis účinky léků genetika mikrobiologie MeSH
- Botrytis účinky léků fyziologie MeSH
- fluorescence MeSH
- geneticky modifikované rostliny MeSH
- kořeny rostlin účinky léků genetika MeSH
- messenger RNA genetika metabolismus MeSH
- nemoci rostlin genetika mikrobiologie MeSH
- odolnost vůči nemocem účinky léků genetika MeSH
- peptidy farmakologie MeSH
- proteolýza účinky léků MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- rostlinné proteiny genetika metabolismus MeSH
- semenáček účinky léků růst a vývoj fyziologie MeSH
- Solanum lycopersicum mikrobiologie MeSH
- subcelulární frakce metabolismus MeSH
- transport RNA účinky léků genetika MeSH
- výhonky rostlin účinky léků genetika MeSH
- zelené fluorescenční proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
