RESUMO
Magnesium (Mg) and calcium (Ca) are essential mineral nutrients poorly supplied in many human food systems. In grazing livestock, Mg and Ca deficiencies are costly welfare issues. Here, we report a Brassica rapa loss-of-function schengen3 (sgn3) mutant, braA.sgn3.a-1, which accumulates twice as much Mg and a third more Ca in its leaves. We mapped braA.sgn3.a to a single recessive locus using a forward ionomic screen of chemically mutagenized lines with subsequent backcrossing and linked-read sequencing of second back-crossed, second filial generation (BC2F2) segregants. Confocal imaging revealed a disrupted root endodermal diffusion barrier, consistent with SGN3 encoding a receptor-like kinase required for normal formation of Casparian strips, as reported in thale cress (Arabidopsis thaliana). Analysis of the spatial distribution of elements showed elevated extracellular Mg concentrations in leaves of braA.sgn3.a-1, hypothesized to result from preferential export of excessive Mg from cells to ensure suitable cellular concentrations. This work confirms a conserved role of SGN3 in controlling nutrient homeostasis in B. rapa, and reveals mechanisms by which plants are able to deal with perturbed shoot element concentrations resulting from a "leaky" root endodermal barrier. Characterization of variation in leaf Mg and Ca accumulation across a mutagenized population of B. rapa shows promise for using such populations in breeding programs to increase edible concentrations of essential human and animal nutrients.
Assuntos
Brassica rapa/genética , Brassica rapa/metabolismo , Cálcio/análise , Cálcio/metabolismo , Genes Recessivos , Magnésio/análise , Magnésio/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Mutação , Folhas de Planta/genética , Folhas de Planta/metabolismoRESUMO
BACKGROUND: Associative transcriptomics has been used extensively in Brassica napus to enable the rapid identification of markers correlated with traits of interest. However, within the important vegetable crop species, Brassica oleracea, the use of associative transcriptomics has been limited due to a lack of fixed genetic resources and the difficulties in generating material due to self-incompatibility. Within Brassica vegetables, the harvestable product can be vegetative or floral tissues and therefore synchronisation of the floral transition is an important goal for growers and breeders. Vernalisation is known to be a key determinant of the floral transition, yet how different vernalisation treatments influence flowering in B. oleracea is not well understood. RESULTS: Here, we present results from phenotyping a diverse set of 69 B. oleracea accessions for heading and flowering traits under different environmental conditions. We developed a new associative transcriptomics pipeline, and inferred and validated a population structure, for the phenotyped accessions. A genome-wide association study identified miR172D as a candidate for the vernalisation response. Gene expression marker association identified variation in expression of BoFLC.C2 as a further candidate for vernalisation response. CONCLUSIONS: This study describes a new pipeline for performing associative transcriptomics studies in B. oleracea. Using flowering time as an example trait, it provides insights into the genetic basis of vernalisation response in B. oleracea through associative transcriptomics and confirms its characterisation as a complex G x E trait. Candidate leads were identified in miR172D and BoFLC.C2. These results could facilitate marker-based breeding efforts to produce B. oleracea lines with more synchronous heading dates, potentially leading to improved yields.
Assuntos
Brassica napus , Brassica , Brassica/genética , Brassica napus/genética , Estudo de Associação Genômica Ampla , Melhoramento Vegetal , TranscriptomaRESUMO
Flowering time is a key adaptive and agronomic trait. In Arabidopsis, natural variation in expression levels of the floral repressor FLOWERING LOCUS C (FLC) leads to differences in vernalization. In Brassica napus there are nine copies of FLC. Here, we study how these multiple FLC paralogues determine vernalization requirement as a system. We collected transcriptome time series for Brassica napus spring, winter, semi-winter, and Siberian kale crop types. Modelling was used to link FLC expression dynamics to floral response following vernalization. We show that relaxed selection pressure has allowed expression of FLC paralogues to diverge, resulting in variation of FLC expression during cold treatment between paralogues and accessions. We find that total FLC expression dynamics best explains differences in cold requirement between cultivars, rather than expression of specific FLC paralogues. The combination of multiple FLC paralogues with different expression dynamics leads to rich behaviour in response to cold and a wide range of vernalization requirements in B. napus. We find evidence for different strategies to determine the response to cold in existing winter rapeseed accessions.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Brassica napus , Brassica rapa , Brassica , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Brassica/metabolismo , Brassica napus/genética , Brassica napus/metabolismo , Flores/genética , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/genética , Proteínas de Domínio MADS/metabolismoRESUMO
BACKGROUND: Transcriptome time series can be used to track the expression of genes during development, allowing the timing, intensity, and dynamics of genetic programmes to be determined. Furthermore, time series analysis can reveal causal relationships between genes, leading to an understanding of how the regulatory networks are rewired during development. Due to its impact on yield, a developmental transition of agricultural interest in crops is the switch from vegetative to floral growth. We previously reported the collection of genome-wide gene expression data during the floral transition in the allopolyploid crop Brassica napus (oilseed rape, OSR). To provide the OSR research community with easy access to this dataset, we have developed the Oilseed Rape Developmental Expression Resource (ORDER; http://order.jic.ac.uk ). RESULTS: ORDER enables users to search for genes of interest and plot expression patterns during the floral transition in both a winter and a spring variety of OSR. We illustrate the utility of ORDER using two case studies: the first investigating the interaction between transcription factors, the second comparing genes that mediate the vernalisation response between OSR and radish (Raphanus sativus L.). All the data is downloadable and the generic website platform underlying ORDER, called AionPlot, is made freely and openly available to facilitate the dissemination of other time series datasets. CONCLUSIONS: ORDER provides the OSR research community with access to a dataset focused on a period of OSR development important for yield. AionPlot, the platform on which ORDER is built, will allow researchers from all fields to share similar time series datasets.
Assuntos
Brassica napus/genética , Bases de Dados Genéticas , Flores/genética , Proteínas de Plantas/genética , Produtos Agrícolas/genética , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Internet , Raphanus/genética , Sementes/genéticaRESUMO
Winter, spring and biennial varieties of Brassica napus that vary in vernalization requirement are grown for vegetable and oil production. Here, we show that the obligate or facultative nature of the vernalization requirement in European winter oilseed rape is determined by allelic variation at a 10 Mbp region on chromosome A02. This region includes orthologues of the key floral regulators FLOWERING LOCUS C (BnaFLC.A02) and FLOWERING LOCUS T (BnaFT.A02). Polymorphism at BnaFLC.A02 and BnaFT.A02, mostly in cis-regulatory regions, results in distinct gene expression dynamics in response to vernalization treatment. Our data suggest allelic variation at BnaFT.A02 is associated with flowering time in the absence of vernalization, while variation at BnaFLC.A02 is associated with flowering time under vernalizing conditions. We hypothesize selection for BnaFLC.A02 and BnaFT.A02 gene expression variation has facilitated the generation of European winter oilseed rape varieties that are adapted to different winter climates. This knowledge will allow for the selection of alleles of flowering time regulators that alter the vernalization requirement of oilseed rape, informing the generation of new varieties with adapted flowering times and improved yields.
Assuntos
Brassica napus , Alelos , Brassica napus/genética , Flores , Estações do AnoRESUMO
Polyploidy is a recurrent feature of eukaryotic evolution and has been linked to increases in complexity, adaptive radiation and speciation. Within angiosperms such events have occurred repeatedly in many plant lineages. Here we investigate the retention and spatio-temporal expression dynamics of duplicated genes predicted to regulate the floral transition in Brassica napus (oilseed rape, OSR). We show that flowering time genes are preferentially retained relative to other genes in the OSR genome. Using a transcriptome time series in two tissues (leaf and shoot apex) across development we show that 67% of these retained flowering time genes are expressed. Furthermore, between 64% (leaf) and 74% (shoot apex) of the retained gene homologues show diverged expression patterns relative to each other across development, suggesting neo- or subfunctionalization. A case study of homologues of the shoot meristem identity gene TFL1 reveals differences in cis-regulatory elements that could explain this divergence. Such differences in the expression dynamics of duplicated genes highlight the challenges involved in translating gene regulatory networks from diploid model systems to more complex polyploid crop species.
Assuntos
Brassica napus/genética , Flores/genética , Genes de Plantas/genética , Poliploidia , Brassica napus/crescimento & desenvolvimento , Duplicação Gênica/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas/fisiologiaRESUMO
Variation in flowering time and response to overwintering has been exploited to breed brassica vegetables that can be harvested year-round. Our knowledge of flowering time control now enables the investigation of the molecular basis of this important variation. Here, we show that a major determinant of heading date variation in Brassica oleracea is from variation in vernalization response through allelic variation at FLOWERING LOCUS C.C2 (BoFLC4). We characterize two alleles of BoFLC.C2 that are both functional and confer a requirement for vernalization, but they show distinct expression dynamics in response to cold. Complementation experiments in Arabidopsis thaliana revealed that the allelic variation results from cis polymorphism at BoFLC.C2, which quantitatively influences the degree of cold-induced epigenetic silencing. This results in one allelic variant conferring consistently later heading under both glasshouse and field conditions through reduced environmental sensitivity. Our results suggest that breeding of brassica varieties for commercially valuable variation in heading date has been achieved through the selection of cis polymorphism at FLC, similar to that underpinning natural variation in A. thaliana. This understanding will allow for the selection of alleles with distinct sensitivities to cold and robust heading dates under variable climatic conditions, and will facilitate the breeding of varieties more resistant to climate change.
Assuntos
Brassica/genética , Flores/fisiologia , Polimorfismo Genético , Arabidopsis , Proteínas de Arabidopsis/genética , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Locos de Características QuantitativasRESUMO
BACKGROUND: Plants adopt different reproductive strategies as an adaptation to growth in a range of climates. In Arabidopsis thaliana FRIGIDA (FRI) confers a vernalization requirement and thus winter annual habit by increasing the expression of the MADS box transcriptional repressor FLOWERING LOCUS C (FLC). Variation at FRI plays a major role in A. thaliana life history strategy, as independent loss-of-function alleles that result in a rapid-cycling habit in different accessions, appear to have evolved many times. The aim of this study was to identify and characterize orthologues of FRI in Brassica oleracea. RESULTS: We describe the characterization of FRI from Brassica oleracea and identify the two B. oleracea FRI orthologues (BolC.FRI.a and BolC.FRI.b). These show extensive amino acid conservation in the central and C-terminal regions to FRI from other Brassicaceae, including A. thaliana, but have a diverged N-terminus. The genes map to two of the three regions of B. oleracea chromosomes syntenic to part of A. thaliana chromosome 5 suggesting that one of the FRI copies has been lost since the ancient triplication event that formed the B. oleracea genome. This genomic position is not syntenic with FRI in A. thaliana and comparative analysis revealed a recombination event within the A. thaliana FRI promoter. This relocated A. thaliana FRI to chromosome 4, very close to the nucleolar organizer region, leaving a fragment of FRI in the syntenic location on A. thaliana chromosome 5. Our data show this rearrangement occurred after the divergence from A. lyrata. We explored the allelic variation at BolC.FRI.a within cultivated B. oleracea germplasm and identified two major alleles, which appear equally functional both to each other and A. thaliana FRI, when expressed as fusions in A. thaliana. CONCLUSIONS: We identify the two Brassica oleracea FRI genes, one of which we show through A. thaliana complementation experiments is functional, and show their genomic location is not syntenic with A. thaliana FRI due to an ancient recombination event. This has complicated previous association analyses of FRI with variation in life history strategy in the Brassica genus.
Assuntos
Alelos , Brassica/genética , Flores/crescimento & desenvolvimento , Proteínas de Plantas/genética , Sequência de Aminoácidos , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis , Brassica/crescimento & desenvolvimento , Mapeamento Cromossômico , Clonagem Molecular , DNA de Plantas/genética , Flores/genética , Genoma de Planta , Genótipo , Dados de Sequência Molecular , Polimorfismo Genético , Regiões Promotoras Genéticas , Recombinação Genética , Análise de Sequência de DNA , SinteniaRESUMO
Comparative transcriptomics can be used to translate an understanding of gene regulatory networks from model systems to less studied species. Here, we use RNA-Seq to determine and compare gene expression dynamics through the floral transition in the model species Arabidopsis thaliana and the closely related crop Brassica rapa. We find that different curve registration functions are required for different genes, indicating that there is no single common 'developmental time' between Arabidopsis and B. rapa. A detailed comparison between Arabidopsis and B. rapa and between two B. rapa accessions reveals different modes of regulation of the key floral integrator SOC1, and that the floral transition in the B. rapa accessions is triggered by different pathways. Our study adds to the mechanistic understanding of the regulatory network of flowering time in rapid cycling B. rapa and highlights the importance of registration methods for the comparison of developmental gene expression data.
RESUMO
Discoveries in model plants grown under optimal conditions can provide important directions for crop improvement. However, it is important to verify whether results can be translated to crop plants grown in the field. In this study, we sought to study the role of MYB28 in the regulation of aliphatic glucosinolate (A-GSL) biosynthesis and associated sulfur metabolism in field-grown Brassica oleracea with the use of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 gene-editing technology. We describe the first myb28 knockout mutant in B. oleracea, and the first CRISPR field trial in the United Kingdom approved and regulated by the UK Department for Environment, Food & Rural Affairs after the reclassification of gene-edited crops as genetically modified organisms by the European Court of Justice on July 25, 2018. We report that knocking out myb28 results in downregulation of A-GSL biosynthesis genes and reduction in accumulation of the methionine-derived glucosinolate, glucoraphanin, in leaves and florets of field-grown myb28 mutant broccoli plants, whereas accumulation of sulfate, S-methyl cysteine sulfoxide, and indole glucosinolate in leaf and floret tissues remained unchanged. These results demonstrate the potential of gene-editing approaches to translate discoveries in fundamental biological processes for improved crop performance.
Assuntos
Brassica/genética , Brassica/metabolismo , Sistemas CRISPR-Cas , Edição de Genes/métodos , Glucosinolatos/biossíntese , Glucosinolatos/genética , Histona Acetiltransferases/genética , Histona Acetiltransferases/metabolismo , Proteínas de Arabidopsis , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Expressão Gênica , Oximas , Plantas Geneticamente Modificadas , Sulfóxidos/metabolismo , Reino UnidoRESUMO
In Arabidopsis thaliana, winter is registered during vernalization through the temperature-dependent repression and epigenetic silencing of floral repressor FLOWERING LOCUS C (FLC). Natural Arabidopsis accessions show considerable variation in vernalization. However, which aspect of the FLC repression mechanism is most important for adaptation to different environments is unclear. By analysing FLC dynamics in natural variants and mutants throughout winter in three field sites, we find that autumnal FLC expression, rather than epigenetic silencing, is the major variable conferred by the distinct Arabidopsis FLChaplotypes. This variation influences flowering responses of Arabidopsis accessions resulting in an interplay between promotion and delay of flowering in different climates to balance survival and, through a post-vernalization effect, reproductive output. These data reveal how expression variation through non-coding cis variation at FLC has enabled Arabidopsis accessions to adapt to different climatic conditions and year-on-year fluctuations.
Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Haplótipos/genética , Proteínas de Domínio MADS , Estações do Ano , Arabidopsis/fisiologia , Proteínas de Arabidopsis/análise , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação para Baixo , Flores/genética , Flores/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Proteínas de Domínio MADS/análise , Proteínas de Domínio MADS/genética , Proteínas de Domínio MADS/metabolismo , Mutação/genética , Suécia , Reino UnidoRESUMO
Plants integrate widely fluctuating temperatures to monitor seasonal progression. Here, we investigate the temperature signals in field conditions that result in vernalisation, the mechanism by which flowering is aligned with spring. We find that multiple, distinct aspects of the temperature profile contribute to vernalisation. In autumn, transient cold temperatures promote transcriptional shutdown of Arabidopsis FLOWERING LOCUS C (FLC), independently of factors conferring epigenetic memory. As winter continues, expression of VERNALIZATION INSENSITIVE3 (VIN3), a factor needed for epigenetic silencing, is upregulated by at least two independent thermosensory processes. One integrates long-term cold temperatures, while the other requires the absence of daily temperatures above 15 °C. The lack of spikes of high temperature, not just prolonged cold, is thus the major driver for vernalisation. Monitoring of peak daily temperature is an effective mechanism to judge seasonal progression, but is likely to have deleterious consequences for vernalisation as the climate becomes more variable.
Assuntos
Arabidopsis/genética , Epigênese Genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Temperatura Baixa , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Ecossistema , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/genética , Proteínas de Domínio MADS/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The Brassica Information Portal (BIP) is a centralised repository for brassica phenotypic data. The site hosts trait data associated with brassica research and breeding experiments conducted on brassica crops, that are used as oilseeds, vegetables, livestock forage and fodder and for biofuels. A key feature is the explicit management of meta-data describing the provenance and relationships between experimental plant materials, as well as trial design and trait descriptors. BIP is an open access and open source project, built on the schema of CropStoreDB, and as such can provide trait data management strategies for any crop data. A new user interface and programmatic submission/retrieval system helps to simplify data access for researchers, breeders and other end-users. BIP opens up the opportunity to apply integrative, cross-project analyses to data generated by the Brassica Research Community. Here, we present a short description of the current status of the repository.
RESUMO
A better understanding of the genetic basis underlying the genotype dependence of Brassica oleracea transformation is enabling researchers to distinguish between recalcitrant and successful candidate genotypes for routine transformation. In this chapter we outline an A. tumefaciens-mediated transformation method for B. oleracea using 4-d-old cotyledonary explants and a model B. oleracea doubled haploid genotype, AG DH1012. After only 3 wk on kanamycin selection, the first transgenic shoots can be isolated. Transformation efficiencies in the region of 10 to 25% (based on 50-125 PCR-positive independent shoots from 500 infected explants) are typically achieved. For researchers wishing to use their own plant genotype, we highlight the tissue culture phenotypes that are conducive to efficient transformation.
Assuntos
Agrobacterium tumefaciens/genética , Brassica/genética , Cotilédone/genética , Técnicas de Transferência de Genes , Plantas Geneticamente Modificadas/genética , Transformação Genética , Brassica/microbiologia , Cotilédone/microbiologia , Resistência a Medicamentos/genética , Marcadores Genéticos , Genótipo , Haploidia , Plantas Geneticamente Modificadas/microbiologiaRESUMO
There is considerable debate about the functionality of long non-coding RNAs (lncRNAs). Lack of sequence conservation has been used to argue against functional relevance. We investigated antisense lncRNAs, called COOLAIR, at the A. thaliana FLC locus and experimentally determined their secondary structure. The major COOLAIR variants are highly structured, organized by exon. The distally polyadenylated transcript has a complex multi-domain structure, altered by a single non-coding SNP defining a functionally distinct A. thaliana FLC haplotype. The A. thaliana COOLAIR secondary structure was used to predict COOLAIR exons in evolutionarily divergent Brassicaceae species. These predictions were validated through chemical probing and cloning. Despite the relatively low nucleotide sequence identity, the structures, including multi-helix junctions, show remarkable evolutionary conservation. In a number of places, the structure is conserved through covariation of a non-contiguous DNA sequence. This structural conservation supports a functional role for COOLAIR transcripts rather than, or in addition to, antisense transcription.
Assuntos
Evolução Molecular , Estrutura Secundária de Proteína , RNA Antissenso/química , RNA Longo não Codificante/química , Arabidopsis , Proteínas de Arabidopsis/química , BrassicaceaeRESUMO
With the accelerating advances in genetics and genomics research in Arabidopsis and Brassica, transformation technologies are now routinely being exploited to elucidate gene function as well as contributing to the development of novel enhanced crops. When a researcher's desired goal is simply to modify or introduce candidate genes into a Brassica, the availability of easy-to-follow protocols and knowledge of readily transformable genotypes becomes a valuable resource. In this chapter we outline a basic A. tumefaciens-mediated transformation method, using 4-day-old cotyledonary explants, that has been successfully applied to a range of different B. oleracea and B. napus genotypes. For demonstration purposes, we focus primarily on the diploid species B. oleracea using a model doubled haploid genotype, AG DH1012. After only 3-4 weeks on kanamycin selection the first transgenic shoots can be isolated. Transformation efficiencies are typically in the region of 15-25 % (based on 15-25 PCR-positive independent shoots from 100 inoculated explants). Most explants will produce multiple shoots (1-3+ per explant) and so the total number of transgenic shoots produced will exceed 15-25 per 100 explant experiment. The protocol is also applicable to B. napus and modifications specific to this species are highlighted accordingly. For researchers wishing to use their own plant genotype, tissue culture phenotypes that are conducive to efficient transformation are also highlighted within this chapter.
Assuntos
Brassica/genética , Técnicas Genéticas , Plantas Geneticamente Modificadas , Agricultura/métodos , Agrobacterium tumefaciens/genética , Brassica/crescimento & desenvolvimento , Brassica napus/genética , Brassica napus/crescimento & desenvolvimento , Técnicas de Cocultura , Cotilédone/genética , Germinação , Haploidia , Brotos de Planta/genética , Sementes/genética , Seleção Genética , Esterilização , Transformação BacterianaRESUMO
The requirement for vernalization, a need for prolonged cold to trigger flowering, aligns reproductive development with favorable spring conditions. In Arabidopsis thaliana vernalization depends on the cold-induced epigenetic silencing of the floral repressor locus FLC. Extensive natural variation in vernalization response is associated with A. thaliana accessions collected from different geographical regions. Here, we analyse natural variation for vernalization temperature requirement in accessions, including those from the northern limit of the A. thaliana range. Vernalization required temperatures above 0°C and was still relatively effective at 14°C in all the accessions. The different accessions had characteristic vernalization temperature profiles. One Northern Swedish accession showed maximum vernalization at 8°C, both at the level of flowering time and FLC chromatin silencing. Historical temperature records predicted all accessions would vernalize in autumn in N. Sweden, a prediction we validated in field transplantation experiments. The vernalization response of the different accessions was monitored over three intervals in the field and found to match that when the average field temperature was given as a constant condition. The vernalization temperature range of 0-14°C meant all accessions fully vernalized before snowfall in N. Sweden. These findings have important implications for understanding the molecular basis of adaptation and for predicting the consequences of climate change on flowering time.
Assuntos
Adaptação Biológica , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Temperatura Baixa , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Arabidopsis/genética , SuéciaRESUMO
Plants have to cope with constantly changing conditions and need to respond to environmental stresses and seasonal changes in temperature and photoperiod. Alignment of their development with particular seasons requires memory mechanisms and an ability to integrate noisy temperature signals over long time scales. An increasingly well understood example of how seasonal changes influence development is vernalization, the acceleration of flowering by prolonged cold. Vernalization has been dissected in Arabidopsis thaliana and shown to involve a Polycomb-based epigenetic memory system. This minireview summarizes our current understanding of this mechanism and its modulation through adaptation. A key concept that has emerged is that cell-autonomous switching between epigenetic states can provide the basis for quantitative accumulation of environmental memory.
Assuntos
Adaptação Fisiológica , Arabidopsis/fisiologia , Estações do Ano , Arabidopsis/genética , Epigênese GenéticaRESUMO
We have explored the genetic basis of variation in vernalization requirement and response in Arabidopsis accessions, selected on the basis of their phenotypic distinctiveness. Phenotyping of F2 populations in different environments, plus fine mapping, indicated possible causative genes. Our data support the identification of FRI and FLC as candidates for the major-effect QTL underlying variation in vernalization response, and identify a weak FLC allele, caused by a Mutator-like transposon, contributing to flowering time variation in two N. American accessions. They also reveal a number of additional QTL that contribute to flowering time variation after saturating vernalization. One of these was the result of expression variation at the FT locus. Overall, our data suggest that distinct phenotypic variation in the vernalization and flowering response of Arabidopsis accessions is accounted for by variation that has arisen independently at relatively few major-effect loci.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Temperatura Baixa , Flores/fisiologia , Variação Genética , Proteínas de Domínio MADS/genética , Locos de Características Quantitativas , Alelos , Arabidopsis/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Fenótipo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Significant advances over the last few years have seen plant-made pharmaceuticals (PMPs) move from the exploratory research phase towards clinical trials, with the first commercial products for human use expected to reach the market by 2009. Europe has yet to witness the commercial application of PMP technology, although at least one product has begun phase II clinical trials with others following close behind. These emerging products are set to challenge the complex and overlapping regulations that currently govern GM plants and 'conventional' pharmaceutical production. The areas of responsibility are being mapped out between the different EU regulatory agencies, with specific guidelines currently being drawn up for the regulation of PMPs. This article discusses issues surrounding the development of robust risk-assessment and risk-management practices based on health and environmental impact, while working with EU regulatory authorities to ensure appropriate regulatory oversight.