title: Stimulation of carotenoid metabolism in arbuscular mycorrhizal roots.
abstract: Development of arbuscular mycorrhizal roots is correlated with accumulation of various isoprenoids, i.e. acyclic C(14) polyene 'mycorradicin' and C(13) cyclohexenone derivatives. We present data indicating a strong stimulation of carotenoid metabolism in such roots. Carotenoid profiling revealed mycorrhiza-specific accumulation of zeta-carotene in Zea mays and Medicago truncatula. Precursor accumulation after inhibition of phytoene desaturase (Pds) activity by norflurazon indicated an increased phytoene biosynthetic capacity in mycorrhizal roots of all species analyzed. Nicotiana tabacum plants transformed with a PDS promoter- GUS construct showed a cell-specific induction of PDS promoter activity in root cells containing arbuscules. Mycorradicin biosynthesis and, partially, mycorrhization were impaired in maize mutants deficient in carotenoid biosynthesis. These data indicate that (1) mycorradicin is probably synthesized via a C(40) precursor carotenoid, (2) carotenoid biosynthesis is induced in mycorrhizal roots, (3) induction occurs, at least partially, at the transcriptional level, and (4) that this may play a functional role during mycorrhization.
authors.affiliation: Leibniz-Institut für Pflanzenbiochemie, Abteilung Sekundärstoffwechsel, Weinberg 3, 06120 Halle, Saale, Germany. tfester@ipb-halle.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Fester
authors.forename: Diana
authors.initials: D
authors.lastname: Schmidt
authors.forename: Swanhild
authors.initials: S
authors.lastname: Lohse
authors.forename: Michael H
authors.initials: MH
authors.lastname: Walter
authors.forename: Giovanni
authors.initials: G
authors.lastname: Giuliano
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bramley
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
authors.forename: Bettina
authors.initials: B
authors.lastname: Hause
authors.forename: Dieter
authors.initials: D
authors.lastname: Strack
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D003998:Dicarboxylic Acids / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D029902:Medicago / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D009154:Mutation; D038821:Mycorrhizae / Q000254:growth & development*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D011090:Polyenes / Q000378:metabolism; D011724:Pyridazines / Q000494:pharmacology; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D003313:Zea mays / Q000235:genetics / Q000378:metabolism / Q000382:microbiology
chemical_list: D003998:Dicarboxylic Acids; D011090:Polyenes; D011724:Pyridazines; C458517:mycorradicin; D002338:Carotenoids; C100185:(all-E) phytoene; D010088:Oxidoreductases; C022398:phytoene dehydrogenase; D005966:Glucuronidase; C008677:norflurazone