Knock-down of the MEP pathway isogene1-deoxy-d-xylulose 5-phosphate synthase 2inhibits formation of arbuscular mycorrhiza-induced apocarotenoids, and abolishes normal expression of mycorrhiza-specific plant marker genes
| Autor: | Dieter Strack, Daniela S. Floß, Helge Küster, Michael H. Walter, Bettina Hause, Peter R. Lange |
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| Rok vydání: | 2008 |
| Předmět: |
mycorrhiza
Plant Science Genes Plant Plant Roots Transcriptome isoprenoid biosynthesis Transformation Genetic Transferases RNA interference Mycorrhizae Medicago truncatula Genetics Mycorrhiza Promoter Regions Genetic Symbiosis Secondary metabolism Oligonucleotide Array Sequence Analysis Plant Proteins Genomic Library biology ATP synthase Reverse Transcriptase Polymerase Chain Reaction Terpenes mycorradicin fungi methylerythritol phosphate pathway transcriptome profiling Cell Biology Plants Genetically Modified biology.organism_classification Carotenoids Isoenzymes Arbuscular mycorrhiza Erythritol Phenotype Biochemistry RNA Plant RNAi biology.protein Apocarotenoid arbuscular RNA Interference Sugar Phosphates |
| Zdroj: | The Plant Journal. 56:86-100 |
| ISSN: | 1365-313X 0960-7412 |
| DOI: | 10.1111/j.1365-313x.2008.03575.x |
| Popis: | The first step of the plastidial methylerythritol phosphate (MEP) pathway is catalyzed by two isoforms of 1-deoxy-D-xylulose 5-phosphate synthase (DXS1 and DXS2). In Medicago truncatula, MtDXS1 and MtDXS2 genes exhibit completely different expression patterns. Most prominently, colonization by arbuscular mycorrhizal (AM) fungi induces the accumulation of certain apocarotenoids (cyclohexenone and mycorradicin derivatives) correlated with the expression of MtDXS2 but not of MtDXS1. To prove a distinct function of DXS2, a selective RNAi approach on MtDXS2 expression was performed in transgenic hairy roots of M. truncatula. Repression of MtDXS2 consistently led to reduced transcript levels in mycorrhizal roots, and to a concomitant reduction of AM-induced apocarotenoid accumulation. The transcript levels of MtDXS1 remained unaltered in RNAi plants, and no phenotypical changes in non-AM plants were observed. Late stages of the AM symbiosis were adversely affected, but only upon strong repression with residual MtDXS2-1 transcript levels remaining below approximately 10%. This condition resulted in a strong decrease in the transcript levels of MtPT4, an AM-specific plant phosphate transporter gene, and in a multitude of other AM-induced plant marker genes, as shown by transcriptome analysis. This was accompanied by an increased proportion of degenerating and dead arbuscules at the expense of mature ones. The data reveal a requirement for DXS2-dependent MEP pathway-based isoprenoid products to sustain mycorrhizal functionality at later stages of the symbiosis. They further validate the concept of a distinct role for DXS2 in secondary metabolism, and offer a novel tool to selectively manipulate the levels of secondary isoprenoids by targeting their precursor supply. |
| Databáze: | OpenAIRE |
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