Analysis of the MYB28, MYB29 and MYB76 transcription factors involved in the biosynthesis of aliphatic glucosinolates in Arabidopsis thaliana

Glucosinolates (GSL) are nitrogen- and sulphur-rich natural plant products that serve as chemoprotective compounds in plant biotic defence reactions against herbivores and pathogens. GS also function as flavour compounds and exhibit strong anticancerogenic properties beneficial to human health. Although considerable progress has been made concerning the biosynthesis of glucosinolates, little is known how plants regulate the synthesis of these metabolites. The MYB28, MYB29 and MYB76 (referred to as HIGH ALIPHATIC GLUCOSINOLATE 1, 3 and 2) transcription factors were identified as novel regulators of glucosinolate biosynthesis. Molecular and biochemical characterization of Arabidopsis gain- and loss-of-function mutants revealed a significant correlation between the MYB28/HAG1, MYB29/HAG3 and MYB76/HAG2 transcript levels and the accumulation of aliphatic Met-derived glucosinolates. MYB28/HAG1, MYB29/HAG3 and MYB76/HAG2 over-expression caused a considerable increase in the level of aliphatic glucosinolates due to the specific activation of genes involved in aliphatic glucosinolate biosynthesis. Disruption of MYB28/HAG1 and MYB29/HAG3 gene functions caused a dramatic decrease in the content of aliphatic glucosinolates, whereas myb76/hag2 loss-of-function mutants showed no changes in glucosinolate profiles except for the slight decrease in the level of 4MSOB glucosinolate. Analysis of the ProHAG:GUS activity revealed similar expression patterns in generative organs and rosette leaves of Arabidopsis plants, covering the main sites of aliphatic glucosinolate accumulation and overlapping with the expression of glucosinolate biosynthetic genes. Mechanical stimuli transiently induced MYB/HAG expression demonstrating their role in early plant responses to biotic stresses. Expression of MYB28/HAG1 was clearly induced by glucose, indicating a novel signaling mechanism for the integration of carbohydrate availability in glucosinolates production, whereas MYB29/HAG3 was shown to be involved in MeJa-induced glucosinolate biosynthesis. Notably, MYB76/HAG2 expression was independent from plant elicitors and seems to play an accessory role in glucosinolate biosynthesis. Besides, MYB28/HAG1 over-expression reduced performance of the generalist lepidopteran herbivore Spodoptera exigua in weight-gain experiments. Finally, MYB28/HAG1, MYB76/HAG2 and MYB29/HAG3 reciprocally trans-activate each other and comprise a complex regulatory network in concert with other regulators (MYB51, MYB34, MYB122, WRKY25 and SLIM1) to control glucosinolate biosynthesis in response to different environmental stimuli

The efficacy of the drug "Doramectin KM 1%" for strongylatoses of the gastrointestinal tract in cattle

veterinary medicine, cattle, parasitic diseases, strongylatoses, gastrointestinal tract, veterinary drugs, doramectin km 1%, английский язык, крс, стронгилятоз, жкт, лечение, ветеринарные препараты, противопаразитарные препараты, дорамекти

Mother tongue as a vehicle of preserving and developing national

родной язык, культурология, национальный язы

Arabidopsis SWI/SNF chromatin remodeling complex binds both promoters and terminators to regulate gene expression

ATP-dependent chromatin remodeling complexes are important regulators of gene expression in Eukaryotes. In plants, SWI/SNF-type complexes have been shown critical for transcriptional control of key developmental processes, growth and stress responses. To gain insight into mechanisms underlying these roles, we performed whole genome mapping of the SWI/SNF catalytic subunit BRM in Arabidopsis thaliana, combined with transcript profiling experiments. Our data showthatBRM occupies thousands of sites in Arabidopsis genome, most of which located within or close to genes. Among identified direct BRM transcriptional targets almost equal numbers were up- and downregulated upon BRM depletion, suggesting that BRM can act as both activator and repressor of gene expression. Interestingly, in addition to genes showing canonical pattern of BRM enrichment near transcription start site, many other genes showed a transcription termination sitecentred BRM occupancy profile. We found that BRMbound 3� gene regions have promoter-like features, including presence of TATA boxes and high H3K4me3 levels, and possess high antisense transcriptional activity which is subjected to both activation and repression by SWI/SNF complex. Our data suggest that binding to gene terminators and controlling transcription of non-coding RNAs is another way through which SWI/SNF complex regulates expression of its targets

Root morphology and seed and leaf ionomic traits in a Brassica napus L. diversity panel show wide phenotypic variation and are characteristic of crop habit

Background: Mineral nutrient uptake and utilisation by plants are controlled by many traits relating to root morphology, ion transport, sequestration and translocation. The aims of this study were to determine the phenotypic diversity in root morphology and leaf and seed mineral composition of a polyploid crop species, Brassica napus L., and how these traits relate to crop habit. Traits were quantified in a diversity panel of up to 387 genotypes: 163 winter, 127 spring, and seven semiwinter oilseed rape (OSR) habits, 35 swede, 15 winter fodder, and 40 exotic/unspecified habits. Root traits of 14 d old seedlings were measured in a ‘pouch and wick’ system (n = ~24 replicates per genotype). The mineral composition of 3–6 rosette-stage leaves, and mature seeds, was determined on compost-grown plants from a designed experiment (n = 5) by inductively coupled plasma-mass spectrometry (ICP-MS). Results: Seed size explained a large proportion of the variation in root length. Winter OSR and fodder habits had longer primary and lateral roots than spring OSR habits, with generally lower mineral concentrations. A comparison of the ratios of elements in leaf and seed parts revealed differences in translocation processes between crop habits, including those likely to be associated with crop-selection for OSR seeds with lower sulphur-containing glucosinolates. Combining root, leaf and seed traits in a discriminant analysis provided the most accurate characterisation of crop habit, illustrating the interdependence of plant tissues. Conclusions: High-throughput morphological and composition phenotyping reveals complex interrelationships between mineral acquisition and accumulation linked to genetic control within and between crop types (habits) in B. napus. Despite its recent genetic ancestry (<10 ky), root morphology, and leaf and seed composition traits could potentially be used in crop improvement, if suitable markers can be identified and if these correspond with suitable agronomy and quality traits

The plastidic bile acid transporter 5 is required for the biosynthesis of methionine-derived glucosinolates in Arabidopsis thaliana

Aliphatic glucosinolate biosynthesis is highly compartmentalized, requiring import of 2-keto acids or amino acids into chloroplasts for side chain elongation and export of the resulting compounds into the cytosol for conversion into glucosinolate. Aliphatic glucosinolate biosynthesis in Arabidopsis thaliana is regulated by three R2R3-MYB transcription factors, the major player being High Aliphatic Glucosinolate 1 (HAG1/MYB28). Here, we show that BAT5, which belongs to the putative bile acid transporter family, is the only member of this family that is transactivated by HAG1/MYB28, HAG2/MYB76, and HAG3/MYB29. Furthermore, two isopropylmalate isomerases genes, IPMI1 and IPMI2, and the isopropylmalate dehydrogenase gene, IPMDH1, were identified as targets of HAG1/MYB28 and the corresponding proteins localized to plastids, suggesting a role in plastidic chain elongation reactions. The BAT proteins also localized to plastids; however, only mutants defective in BAT5 function contained strongly reduced levels of aliphatic glucosinolates. The bat5 mutant chemotype was rescued by induced overexpression of BAT5. Feeding experiments using 2-keto acids and amino acids of different chain length suggest that BAT5 is a plastidic transporter of (chain-elongated) 2-keto acids. Mechanical stimuli and methyl jasmonate transiently induced BAT5 expression in inflorescences and leaves. Thus, BAT5 was identified as the first transporter component of the aliphatic glucosinolate biosynthetic pathway

A simplified method for the analysis of transcription factor-promoter interactions that allows high-throughput data generation

Transient expression systems are intensively used to study the transactivation potential of transcription factors and to confirm target promoters. Here we present a novel system based on the high-efficiency transformation of cultured Arabidopsis thaliana cells by agrobacteria. To demonstrate the potential of this system, we compared it with a commonly used protoplast transfection assay, and studied the regulation of phenylpropanoid biosynthetic pathway genes by various transcription factors. Both systems led to comparable results on the regulation of the promoters tested. However, the agrobacterium-mediated co-transformation assay needs significantly less time, requires only mixing of cultured plant cells with agrobacteria, is less labour-intensive and allows handling of multiple assays in parallel, making it suitable for medium- to high-throughput analyses. In addition, the binary vectors used are the same for both cell-based assays and stable plant transformations.Bettina Berger, Ralf Stracke, Ruslan Yatusevich, Bernd Weisshaar, Ulf-Ingo Flügge and Tamara Gigolashvil

A simplified method for the analysis of transcription factor-promoter interactions that allows high-throughput data generation

Berger B, Stracke R, Yatusevich R, Weisshaar B, Fluegge U-I, Gigolashvili T. A simplified method for the analysis of transcription factor-promoter interactions that allows high-throughput data generation. The Plant Journal. 2007;50(5):911-916