@phdthesis{Bielecka2007,
  author    = {Bielecka, Monika},
  title     = {Analysis of transcription factors under sulphur deficiency stress},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14812},
  school      = {Universit{\"a}t Potsdam},
  year      = {2007},
  abstract  = {Sulphur, a macronutrient essential for plant growth, is among the most versatile elements in living organisms. Unfortunately, little is known about regulation of sulphate uptake and assimilation by plants. Identification of sulphate signalling processes will allow to control sulphate acquisition and assimilation and may prove useful in the future to improve sulphur-use efficiency in agriculture. Many of genes involved in sulphate metabolism are regulated on transcriptional level by products of other genes called transcription factors (TF). Several published experiments revealed TF genes that respond to sulphate deprivation, but none of these have been so far been characterized functionally. Thus, we aimed at identifying and characterising transcription factors that control sulphate metabolism in the model plant Arabidopsis thaliana. To achieve that goal we postulated that factors regulating Arabidopsis responses to inorganic sulphate deficiency change their transcriptional levels under sulphur-limited conditions. By comparing TF transcript profiles from plants grown on different sulphate regimes, we identified TF genes that may specifically induce or repress changes in expression of genes that allow plants to adapt to changes in sulphate availability. Candidate genes obtained from this screening were tested by reverse genetics approaches. Transgenic plants constitutively overproducing selected TF genes and mutant plants, lacking functional selected TF genes (knock out), were used. By comparing metabolite and transcript profiles from transgenic and wild type plants we aimed at confirming the role of selected AP2 TF candidate genes in plant adaptation to sulphur unavailability. After preliminary characterisation of WRKY24 and MYB93 TF genes, we postulate that these factors are involved in a complex multifactorial regulatory network, in which WRKY24 and MYB93 would act as superior factors regulating other transcription factors directly involved in the regulation of S-metabolism genes. Results obtained for plants overproducing TOE1 and TOE2 TF genes suggests that these factors may be involved in a mechanism, which is promoting synthesis of an essential amino acid, methionine, over synthesis of another amino acid, cysteine. Thus, TOE1 and TOE2 genes might be a part of transcriptional regulation of methionine synthesis. Approaches creating genetically manipulated plants may produce plant phenotypes of immediate biotechnological interest, such as plants with increased sulphate or sulphate-containing amino acid content, or better adapted to the sulphate unavailability.},
  language  = {en}
}