Boller, Thomas* Dotaz Zobrazit nápovědu
Vitamin B(6) (pyridoxal 5'-phosphate) is an essential cofactor of many metabolic enzymes. Plants biosynthesize the vitamin de novo employing two enzymes, pyridoxine synthase1 (PDX1) and PDX2. In Arabidopsis (Arabidopsis thaliana), there are two catalytically active paralogs of PDX1 (PDX1.1 and PDX1.3) producing the vitamin at comparable rates. Since single mutants are viable but the pdx1.1 pdx1.3 double mutant is lethal, the corresponding enzymes seem redundant. However, the single mutants exhibit substantial phenotypic differences, particularly at the level of root development, with pdx1.3 being more impaired than pdx1.1. Here, we investigate the differential regulation of PDX1.1 and PDX1.3 by identifying factors involved in their disparate phenotypes. Swapped-promoter experiments clarify the presence of distinct regulatory elements in the upstream regions of both genes. Exogenous sucrose (Suc) triggers impaired ethylene production in both mutants but is more severe in pdx1.3 than in pdx1.1. Interestingly, Suc specifically represses PDX1.1 expression, accounting for the stronger vitamin B6 deficit in pdx1.3 compared with pdx1.1. Surprisingly, Suc enhances auxin levels in pdx1.1, whereas the levels are diminished in pdx1.3. In the case of pdx1.3, the previously reported reduced meristem activity combined with the impaired ethylene and auxin levels manifest the specific root developmental defects. Moreover, it is the deficit in ethylene production and/or signaling that triggers this outcome. On the other hand, we hypothesize that it is the increased auxin content of pdx1.1 that is responsible for the root developmental defects observed therein. We conclude that PDX1.1 and PDX1.3 play partially nonredundant roles and are differentially regulated as manifested in disparate root growth impairment morphologies.
- MeSH
- Arabidopsis růst a vývoj metabolismus fyziologie MeSH
- fenotyp MeSH
- homeostáza fyziologie MeSH
- kořeny rostlin růst a vývoj MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku metabolismus fyziologie MeSH
- regulátory růstu rostlin metabolismus fyziologie MeSH
- transferasy dusíkatých skupin metabolismus fyziologie MeSH
- vitamin B6 biosyntéza fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We characterized the molecular function of the Pseudomonas syringae pv. tomato DC3000 (Pto) effector HopQ1. In silico studies suggest that HopQ1 might possess nucleoside hydrolase activity based on the presence of a characteristic aspartate motif. Transgenic Arabidopsis lines expressing HopQ1 or HopQ1 aspartate mutant variants were characterized with respect to flagellin triggered immunity, phenotype and changes in phytohormone content by high-performance liquid chromatography-MS (HPLC-MS). We found that HopQ1, but not its aspartate mutants, suppressed all tested immunity marker assays. Suppression of immunity was the result of a lack of the flagellin receptor FLS2, whose gene expression was abolished by HopQ1 in a promoter-dependent manner. Furthermore, HopQ1 induced cytokinin signaling in Arabidopsis and the elevation in cytokinin signaling appears to be responsible for the attenuation of FLS2 expression. We conclude that HopQ1 can activate cytokinin signaling and that moderate activation of cytokinin signaling leads to suppression of FLS2 accumulation and thus defense signaling.
- MeSH
- Arabidopsis účinky léků imunologie fyziologie MeSH
- bakteriální proteiny genetika fyziologie MeSH
- cytokininy metabolismus farmakologie MeSH
- geneticky modifikované rostliny metabolismus MeSH
- odolnost vůči nemocem * MeSH
- proteinkinasy metabolismus MeSH
- proteiny huseníčku metabolismus MeSH
- Pseudomonas syringae genetika fyziologie MeSH
- regulátory růstu rostlin metabolismus MeSH
- signální transdukce MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The study of moral judgements often centres on moral dilemmas in which options consistent with deontological perspectives (that is, emphasizing rules, individual rights and duties) are in conflict with options consistent with utilitarian judgements (that is, following the greater good based on consequences). Greene et al. (2009) showed that psychological and situational factors (for example, the intent of the agent or the presence of physical contact between the agent and the victim) can play an important role in moral dilemma judgements (for example, the trolley problem). Our knowledge is limited concerning both the universality of these effects outside the United States and the impact of culture on the situational and psychological factors affecting moral judgements. Thus, we empirically tested the universality of the effects of intent and personal force on moral dilemma judgements by replicating the experiments of Greene et al. in 45 countries from all inhabited continents. We found that personal force and its interaction with intention exert influence on moral judgements in the US and Western cultural clusters, replicating and expanding the original findings. Moreover, the personal force effect was present in all cultural clusters, suggesting it is culturally universal. The evidence for the cultural universality of the interaction effect was inconclusive in the Eastern and Southern cultural clusters (depending on exclusion criteria). We found no strong association between collectivism/individualism and moral dilemma judgements.
