Stimulation of carotenoid metabolism in arbuscular mycorrhizal roots.
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.
Fester
Thomas
T
Leibniz-Institut für Pflanzenbiochemie, Abteilung Sekundärstoffwechsel, Weinberg 3, 06120 Halle, Saale, Germany. tfester@ipb-halle.de
Schmidt
Diana
D
Lohse
Swanhild
S
Walter
Michael H
MH
Giuliano
Giovanni
G
Bramley
Peter M
PM
Fraser
Paul D
PD
Hause
Bettina
B
Strack
Dieter
D
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
D003998:Dicarboxylic Acids; D011090:Polyenes; D011724:Pyridazines; C458517:mycorradicin; D002338:Carotenoids; C100185:(all-E) phytoene; D010088:Oxidoreductases; C022398:phytoene dehydrogenase; D005966:Glucuronidase; C008677:norflurazone