Stress responses in alfalfa (Medicago sativa L.) XIX. Transcriptional activation of oxidative pentose phosphate pathway genes at the onset of the isoflavonoid phytoalexin response
| Autor: | Richard A. Dixon, Basil S. Shorrosh, Theo Fahrendorf, Weiting Ni |
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| Rok vydání: | 1995 |
| Předmět: |
Transcriptional Activation
Pterocarpans Molecular Sequence Data Dehydrogenase Plant Science Glucosephosphate Dehydrogenase Pentose phosphate pathway Biology Pentose Phosphate Pathway chemistry.chemical_compound Isoflavonoid Gene Expression Regulation Plant Genetics Glucose-6-phosphate dehydrogenase Benzopyrans Amino Acid Sequence Gene Cells Cultured Phenylalanine Ammonia-Lyase chemistry.chemical_classification Base Sequence Phosphogluconate Dehydrogenase Phytoalexin Gene Expression Regulation Developmental food and beverages Hydrogen Peroxide General Medicine Elicitor Enzyme chemistry Biochemistry Oxidation-Reduction Agronomy and Crop Science NADP Medicago sativa Signal Transduction |
| Zdroj: | Plant Molecular Biology. 28:885-900 |
| ISSN: | 1573-5028 0167-4412 |
| DOI: | 10.1007/bf00042073 |
| Popis: | We have isolated cDNA clones encoding the pentose phosphate pathway enzymes 6-phosphogluconate dehydrogenase (6PGDH, EC 1.1.1.44) and glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) from alfalfa (Medicago sativa L.). These exhibit extensive nucleotide and amino acid sequence similarity to the corresponding genes from bacteria, Drosophila and mammals. Transcripts encoding both enzymes are expressed at high levels in roots and nodules. Exposure of alfalfa suspension cells to an elicitor from yeast cell walls results in co-ordinated increases in transcription rates for both genes, followed by increased steady state transcript levels but only slightly increased extractable enzyme activities, at the onset of accumulation of isoflavonoid phytoalexins. Levels of NADPH and NADP remain relatively constant in alfalfa cells following elicitation. The rapid transcriptional activation of 6PGDH and G6PDH does not therefore appear to be a response to altered pyridine nucleotide redox state. These genes appear to respond to early events in elicitor-mediated signalling rather than to subsequent elicitor-induced changes in secondary metabolism. Hydrogen peroxide, a potential signal for elicitation of anti-oxidative genes in biologically stressed plant cells, did not induce 6PGDH or G6PDH transcripts or enzymatic activity. |
| Databáze: | OpenAIRE |
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