Parasitoids acting as biocontrol agents provide farmers with valuable ecosystem services, but are sensitive to insecticides applied against pests. Besides lethal effects of insecticides, sublethal effects observed among survivors may further influence parasitoids' performance. However, information on sublethal effects is scattered across case studies, without a quantitative synthesis and evaluation of generality of respective data. We conducted an analysis of 85 primary empirical datasets to quantify sublethal effects of insecticide application on two key parameters of parasitoid fitness, offspring production and proportion of females among offspring (i.e. sex ratio). To create a direct link to existing agricultural practices, we primarily focused on studies in which parasitoids were exposed to field-recommended concentrations of insecticides. Insecticide-exposed females produced substantially fewer and more male-biased offspring, accounting for an average of about 28% cumulative loss in parasitoid reproductive capacity per generation. The magnitude of sublethal effects was significantly affected by insecticide mode of action, with broad-spectrum insecticides being particularly harmful to parasitoid reproductive performance. Transgenic crops and toxins derived from such plants were generally associated with weaker sublethal effects than majority of synthetic insecticides. Nevertheless, species responses, even to the same insecticides and transgenic crops, showed high variability, cautioning against extrapolating results from individual studies to a wider range of species. Overall, our results indicate that sublethal side-effects on parasitoid reproductive performance represent a significant and widespread cost of insecticides that should explicitly be taken into account when evaluating their harmfulness. Linking laboratory results to field situations remains a key challenge for future research.

• MeSH
• geneticky modifikované rostliny účinky léků   růst a vývoj   parazitologie   MeSH
• Hymenoptera účinky léků   růst a vývoj   MeSH
• insekticidy toxicita   MeSH
• interakce hostitele a parazita účinky léků   MeSH
• LD50 MeSH
• rozmnožování * MeSH
• sexuální faktory MeSH
• zemědělské plodiny účinky léků   růst a vývoj   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Understanding indirect, trophic-level effects of genetically engineered plants, expressing insecticidal proteins derived from the bacterium, Bacillus thuringiensis (Bt), is essential to the ecological risk assessment process. In this study, we examine potential indirect, trophic-level effects of Bt-sensitive prey using the predator, Harmonia axyridis (Pallas), feeding upon Spodoptera frugiperda (J.E. Smith) larvae, which had delayed development (lower body mass) following ingestion of Cry1Ab maize leaves. We found no adverse effects on development and survival when H. axyridis larvae were fed S. frugiperda larvae that had fed on Cry1Ab maize tissue. Presence of Cry1Ab in H. axyridis decreased considerably after switching to another diet within 48 h. In a no-choice assay, H. axyridis larvae consumed more Bt-fed S. frugiperda than non-Bt-fed larvae. Preference for S. frugiperda feeding on Bt maize was confirmed in subsequent choice assays with H. axyridis predation on Bt-fed, 1-5-d-old S. frugiperda larvae. We suggest that H. axyridis preferred prey, not based on whether it had fed on Bt or non-Bt maize, but rather on larval mass, and they compensated for the nutritional deficiency of lighter larvae through increased consumption. Pest larvae with variable levels of resistance developing on Bt diet are often stunted versus sensitive larvae developing on non-Bt diet. It is possible that such larvae may be preferentially removed from local field populations. These results may have implications for insect resistance management and may be played out under field conditions where seed blends of Bt and non-Bt hybrids are planted.

• MeSH
• Bacillus thuringiensis klasifikace   MeSH
• bakteriální proteiny metabolismus   MeSH
• biologická kontrola škůdců * MeSH
• brouci růst a vývoj   fyziologie   MeSH
• endotoxiny metabolismus   MeSH
• geneticky modifikované rostliny genetika   růst a vývoj   fyziologie   MeSH
• hemolyziny metabolismus   MeSH
• kukuřice setá genetika   růst a vývoj   fyziologie   MeSH
• larva růst a vývoj   mikrobiologie   fyziologie   MeSH
• potravní řetězec * MeSH
• predátorské chování * MeSH
• Spodoptera růst a vývoj   mikrobiologie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The osmotin protein is involved in both monocot and dicot plant responses to biotic and abiotic stress. To determine the biological activity of osmotin, the gene was amplified from tobacco genomic DNA, fused with the hexahistidine tag motif and successfully expressed in Escherichia coli, after which the recombinant osmotin was purified and renatured. Various activities were then tested, including hemolytic activity, toxicity against human embryonic kidney cells, and the antifungal activity of the recombinant osmotin. We found that osmotin had no adverse effects on human kidney cells up to a concentration of 500 μg.ml(-)(1). However, the purified osmotin also had significant antimicrobial activity, specifically against fungal pathogens causing candidiasis and otitis, and against the common food pathogens. Using the osmotin-Agrobacterium construct, the osmotin gene was inserted into tobacco plants in order to facilitate the isolation of recombinant protein. Using qPCR, the presence and copy number of the transgene was detected in the tobacco plant DNA. The transgene was also quantified using mRNA, and results indicated a strong expression profile, however the native protein has been never isolated. Once the transgene presence was confirmed, the transgenic tobacco plants were grown in high saline concentrations and monitored for seed germination and chlorophyll content as indicators of overall plant health. Results indicated that the transgenic tobacco plants had a higher tolerance for osmotic stress. These results indicate that the osmotin gene has the potential to increase crop tolerance to stresses such as fungal attack and unfavorable osmotic conditions.

• MeSH
• geneticky modifikované rostliny * genetika   růst a vývoj   metabolismus   MeSH
• halotolerantní rostliny * genetika   růst a vývoj   metabolismus   MeSH
• lidé MeSH
• rostlinné proteiny * biosyntéza   genetika   MeSH
• tabák * genetika   růst a vývoj   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Cytokinins, a class of phytohormones, are adenine derivatives common to many different organisms. In plants, these play a crucial role as regulators of plant development and the reaction to abiotic and biotic stress. Key enzymes in the cytokinin synthesis and degradation in modern land plants are the isopentyl transferases and the cytokinin dehydrogenases, respectively. Their encoding genes have been probably introduced into the plant lineage during the primary endosymbiosis. To shed light on the evolution of these proteins, the genes homologous to plant adenylate isopentenyl transferase and cytokinin dehydrogenase were amplified from the genomic DNA of cyanobacterium Nostoc sp. PCC 7120 and expressed in Escherichia coli. The putative isopentenyl transferase was shown to be functional in a biochemical assay. In contrast, no enzymatic activity was detected for the putative cytokinin dehydrogenase, even though the principal domains necessary for its function are present. Several mutant variants, in which conserved amino acids in land plant cytokinin dehydrogenases had been restored, were inactive. A combination of experimental data with phylogenetic analysis indicates that adenylate-type isopentenyl transferases might have evolved several times independently. While the Nostoc genome contains a gene coding for protein with characteristics of cytokinin dehydrogenase, the organism is not able to break down cytokinins in the way shown for land plants.

• MeSH
• biologická evoluce MeSH
• cytokininy metabolismus   MeSH
• Escherichia coli enzymologie   růst a vývoj   MeSH
• fylogeneze MeSH
• geneticky modifikované rostliny genetika   růst a vývoj   metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• mutace genetika   MeSH
• mutageneze cílená MeSH
• Nostoc enzymologie   genetika   MeSH
• oxidoreduktasy genetika   metabolismus   MeSH
• prenyltransferáza genetika   metabolismus   MeSH
• regulace genové exprese enzymů MeSH
• rekombinantní proteiny metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• tabák enzymologie   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Plant growth depends on stem cell niches in meristems. In the root apical meristem, the quiescent center (QC) cells form a niche together with the surrounding stem cells. Stem cells produce daughter cells that are displaced into a transit-amplifying (TA) domain of the root meristem. TA cells divide several times to provide cells for growth. SHORTROOT (SHR) and SCARECROW (SCR) are key regulators of the stem cell niche. Cytokinin controls TA cell activities in a dose-dependent manner. Although the regulatory programs in each compartment of the root meristem have been identified, it is still unclear how they coordinate one another. Here, we investigate how PHABULOSA (PHB), under the posttranscriptional control of SHR and SCR, regulates TA cell activities. The root meristem and growth defects in shr or scr mutants were significantly recovered in the shr phb or scr phb double mutant, respectively. This rescue in root growth occurs in the absence of a QC. Conversely, when the modified PHB, which is highly resistant to microRNA, was expressed throughout the stele of the wild-type root meristem, root growth became very similar to that observed in the shr; however, the identity of the QC was unaffected. Interestingly, a moderate increase in PHB resulted in a root meristem phenotype similar to that observed following the application of high levels of cytokinin. Our protoplast assay and transgenic approach using ARR10 suggest that the depletion of TA cells by high PHB in the stele occurs via the repression of B-ARR activities. This regulatory mechanism seems to help to maintain the cytokinin homeostasis in the meristem. Taken together, our study suggests that PHB can dynamically regulate TA cell activities in a QC-independent manner, and that the SHR-PHB pathway enables a robust root growth system by coordinating the stem cell niche and TA domain.

• MeSH
• Arabidopsis genetika   růst a vývoj   MeSH
• buněčné dělení genetika   MeSH
• cytokininy genetika   metabolismus   MeSH
• DNA vazebné proteiny genetika   MeSH
• fenotyp MeSH
• geneticky modifikované rostliny růst a vývoj   MeSH
• homeodoménové proteiny biosyntéza   genetika   MeSH
• homeostáza MeSH
• kořeny rostlin genetika   růst a vývoj   MeSH
• meristém genetika   růst a vývoj   MeSH
• nika kmenových buněk genetika   MeSH
• proteiny huseníčku biosyntéza   genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• transkripční faktory genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

• Klíčová slova
• semena rostlin, glyfosát,
• MeSH
• geneticky modifikované potraviny MeSH
• geneticky modifikované rostliny * růst a vývoj   toxicita   MeSH
• herbicidy MeSH
• insekticidy toxicita   MeSH
• lidé MeSH
• Check Tag
• lidé MeSH

Dual-specificity mitogen-activated protein kinases kinases (MAPKKs) are the immediate upstream activators of MAPKs. They simultaneously phosphorylate the TXY motif within the activation loop of MAPKs, allowing them to interact with and regulate multiple substrates. Often, the activation of MAPKs triggers their nuclear translocation. However, the spatiotemporal dynamics and the physiological consequences of the activation of MAPKs, particularly in plants, are still poorly understood. Here, we studied the activation and localization of the Medicago sativa stress-induced MAPKK (SIMKK)-SIMK module after salt stress. In the inactive state, SIMKK and SIMK co-localized in the cytoplasm and in the nucleus. Upon salt stress, however, a substantial part of the nuclear pool of both SIMKK and SIMK relocated to cytoplasmic compartments. The course of nucleocytoplasmic shuttling of SIMK correlated temporally with the dual phosphorylation of the pTEpY motif. SIMKK function was further studied in Arabidopsis plants overexpressing SIMKK-yellow fluorescent protein (YFP) fusions. SIMKK-YFP plants showed enhanced activation of Arabidopsis MPK3 and MPK6 kinases upon salt treatment and exhibited high sensitivity against salt stress at the seedling stage, although they were salt insensitive during seed germination. Proteomic analysis of SIMKK-YFP overexpressors indicated the differential regulation of proteins directly or indirectly involved in salt stress responses. These proteins included catalase, peroxiredoxin, glutathione S-transferase, nucleoside diphosphate kinase 1, endoplasmic reticulum luminal-binding protein 2, and finally plasma membrane aquaporins. In conclusion, Arabidopsis seedlings overexpressing SIMKK-YFP exhibited higher salt sensitivity consistent with their proteome composition and with the presumptive MPK3/MPK6 hijacking of the salt response pathway.

• MeSH
• aktivace enzymů MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   MeSH
• exprese genu MeSH
• geneticky modifikované rostliny genetika   růst a vývoj   metabolismus   MeSH
• Medicago sativa enzymologie   genetika   MeSH
• mitogenem aktivované proteinkinasy kinas genetika   metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• semenáček genetika   růst a vývoj   metabolismus   MeSH
• soli metabolismus   MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH