| Description: | Sulfur is a macronutrient required by plants. It is taken up from the soil solution as in the form of sulfate anion and assimilated into Cys, GSH, Met and various metabolites. Cys residues in proteins form disulfide bonds that may affect the tertiary structures and enzyme activities. This redox balance is mediated by the disulfide/thiol interchange of thioredoxin or glutaredoxin using NADPH as an electron donor. Thus, sulfate assimilation plays important roles not only in the sulfur nutrition but also in the ubiquitous process that may regulate the biochemical reactions of various metabolic pathways.This study is aimed to identify the genes responsive to sulfur limitation stress. Sulfur limitation initially causes expression of sulfate transporter genes involved in the uptake and distribution of sulfate in plants. We have recently isolated 7 cell type specific sulfate transporter genes from Arabidopsis. In sulfate-starved plants, expression of the high-affinity transporter, AtST1-1, is induced in root epidermis and cortex for acquisition of sulfur. The low affinity transporter, AtST2-1 (AST68), accumulates in the root vascular tissue by sulfate starvation for root-to-shoot transport of sulfate. These studies have shown that the whole-plant process of sulfate transport is coordinately regulated by the expression of these 2 sulfate transporter genes under sulfur limited conditions. Recent studies have proposed that feeding of O-acetylserine, GSH and selenate may regulate the expression of AtST1-1 and AtST2-1 (AST68) in roots either positively or negatively. However, regulatory proteins that may directly control the expression of these genes have not been identified yet.The mRNA for the arrays will be prepared from the roots of Arabidopsis thaliana ecotype Columbia plants grown on the control and sulfate-less media. The quality of the RNA preparation will be strictly controlled calibrating with the expression of the 2 inducible sulfate transporter genes, AtST1-1 and AtST2-1 (AST68). Genes identified on the array are expected to encode the proteins required for acclimation to sulfur limitation stress. Further, they may have regulatory functions for the expression of AtST1-1 and AtST2-1 (AST68). Related papers/ Takahashi, H. et al. (1997) Proc Natl Acad Sci USA, 94: 11102-11107/ Leustek, T. and Saito, K. (1999) Plant Physiol, 120: 637-643. |
NASCArrays Information at The BAR
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