Journal Article

Genetic Evidence for the Role of Isopentenyl Diphosphate Isomerases in the Mevalonate Pathway and Plant Development in Arabidopsis

Kazunori Okada, Hiroyuki Kasahara, Shinjiro Yamaguchi, Hiroshi Kawaide, Yuji Kamiya, Hideaki Nojiri and Hisakazu Yamane

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 4, pages 604-616
Published in print April 2008 | ISSN: 0032-0781
Published online April 2008 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcn032
Genetic Evidence for the Role of Isopentenyl Diphosphate Isomerases in the Mevalonate Pathway and Plant Development in Arabidopsis

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Isopentenyl/dimethylallyl diphosphate isomerase (IPI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), which are the universal C5 units of isoprenoids. In plants, IPP and DMAPP are synthesized via the cytosolic mevalonate (MVA) and plastidic methylerythritol phosphate (MEP) pathways, respectively. However, the role of IPI in each pathway and in plant development is unknown due to a lack of genetic studies using IPI-defective mutants. Here, we show that the atipi1atipi2 double mutant, which is defective in two Arabidopsis IPI isozymes, exhibits dwarfism and male sterility under long-day conditions and decreased pigmentation under continuous light, whereas the atipi1 and atipi2 single mutants are phenotypically normal. We also show that the sterol and ubiquinone levels in the double mutant are <50% of those in wild-type plants, and that the male-sterile phenotype is chemically complemented by squalene, a sterol precursor. In vivo isotope labeling experiments using the atipi1atipi2 double mutant revealed a decrease in the incorporation of MVA (in its lactone form) into sterols, with no decrease in the incorporation of MEP pathway intermediates into tocopherol. These results demonstrate a critical role for IPI in isoprenoid biosynthesis via the MVA pathway, and they imply that IPI is essential for the maintenance of appropriate levels of IPP and DMAPP in different subcellular compartments in plants.

Keywords: Dimethylallyl diphosphate; IPP isomerase; Isopentenyl diphosphate; MEP pathway; MVA pathway

Journal Article.  7740 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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