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Identification of mutants in metabolically regulated gene expression
Author(s) -
Martin Thomas,
Hellmann Hanjo,
Schmidt Renate,
Willmitzer Lothar,
Frommer Wolf B.
Publication year - 1997
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1997.11010053.x
Subject(s) - mutant , arabidopsis , gene , biology , gene expression , transgene , regulation of gene expression , sucrose , transduction (biophysics) , mutation , signal transduction , mutagenesis , biochemistry , promoter , genetics , microbiology and biotechnology
Sucrose is the main transported form of assimilates, but, significantly, it also regulates a variety of processes such as photosynthesis and carbon or nitrogen storage. The effects of high sucrose levels are mediated directly by modulation of gene expression. The regulation of storage protein accumulation, here patatin from potato tubers, was used as a model system to study sucrose mediated signal transduction. The transcriptional regulation of patatin genes is conserved in transgenic Arabidopsis , as shown by the analysis of expression of two classes of patatin promoters fused to uid A. Two distinctly different patterns of gene expression were observed. In roots, class I promoter expression is strongly dependent on the exogenous supply of sugars. 3‐ O ‐methylglucose induction indicates that the sensor is located upstream of hexokinase. In contrast, the class II promoter is constitutively active in root tips and hydatodes. The progeny of a homozygous class I line was mutagenized with ethyl methane sulphonate and screened for signal transduction mutants using a non‐destructive screening system for GUS activity. Four mutants showing reduced sucrose responses ( rsr ) and two mutants with modified expression patterns ( mep ) regarding the root tip were identified. In backcross analyses, it was shown that rsr1‐1 carries a recessive trans mutation whereas rsr4‐1 seems to be a semi‐dominant trans mutation in sugar‐mediated gene regulation.