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Hyper‐gravity effects on the Arabidopsis transcriptome
Author(s) -
Martzivanou Maria,
Hampp Rüdiger
Publication year - 2003
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2003.00092.x
Subject(s) - biochemistry , biology , gene expression , arabidopsis thaliana , arabidopsis , gene , microbiology and biotechnology , mutant
Callus cultures of Arabidopsis thaliana (cv. Columbia) in Petri dishes were exposed to altered g ‐forces by centrifugation (1–10 g ). Using semi‐quantitative RT–PCR transcripts of genes coding for metabolic key enzymes (ADP‐glucose pyrophosphorylase, ADPG‐PP; β‐amylase, fructose‐1,6‐bisphosphatase, FBPase; glyceraldehyde‐P dehydrogenase, GAPDH; hydroxymethylglutaryl‐CoA reductase, HMG; phenylalanine‐ammonium‐lyase, PAL; PEP carboxylase, PEPC) were used to monitor threshold conditions for g‐number (all) and time of exposure (β‐amylase) which led to altered amounts of the gene product. Exposure to approximately 5 g and higher for 1 h resulted in altered transcript levels: transcripts of β‐amylase, PAL, and PEPC were increased, those of ADPG‐PP decreased, while those of FBPase, GAPDH, and HMG were not affected. This probably indicates a shift from starch synthesis to starch degradation and increased rates of anaplerosis (PEPC: supply of ketoacids for amino acid synthesis). In order to get more information about g ‐related effects on gene expression, we used a 1‐h exposure to 7 g for a microarray analysis, using a commercial A. thaliana chip with 4105 unique annotated clusters/genes (IncyteGenomics). Transcripts of more than 200 genes were significantly increased in amount (ratio 7 g /1 g control; 2 1.6 and larger). They fall into several categories. Transcripts coding for enzymes of major pathways form the largest group (25%), followed by gene products involved in cellular organization and cell wall formation/rearrangement (17%), signalling, phosphorylation/dephosphorylation (12%), proteolysis and transport (10% each), hormone synthesis plus related events (8%), defense (4%), stress‐response (2%), and gravi‐sensing (2%). Many of the alterations are part of a general stress response, but some changes related to the synthesis/rearrangement of cell wall components could be more hyper‐ g ‐specific. We only found few gene products, which were decreased in relation to 1 g controls, and these were less significant (ratio < 2 1.6 ). We thus assume that g ‐forces above a threshold of about 5 g for 1 h are sensed by plant cells in general, causing distinct metabolic responses, which obviously in part, are regulated by gene expression.