Occurrence and localization of apocarotenoids in arbuscular mycorrhizal plant roots.
The core structure of the yellow pigment from arbuscular mycorrhizal (AM) maize roots contains the apocarotenoids mycorradicin (an acyclic C14 polyene) and blumenol C cellobioside (a C13 cyclohexenone diglucoside). The pigment seems to be a mixture of different esterification products of these apocarotenoids. It is insoluble in water and accumulates as hydrophobic droplets in the vacuoles of root cortical cells. Screening 58 species from 36 different plant families, we detected mycorradicin in mycorrhizal roots of all Liliopsida analyzed and of a considerable number of Rosopsida, but also species were found in which mycorradicin was undetectable in mycorrhizal roots. Kinetic experiments and microscopic analyses indicate that accumulation of the yellow pigment is correlated with the concomitant degradation of arbuscules and the extensive plastid network covering these haustorium-like fungal structures. The role of the apocarotenoids in mycorrhizal roots is still unknown. The potential C40 carotenoid precursors, however, are more likely to be of functional importance in the development and functioning of arbuscules.
Fester
Thomas
T
Institut für Pflanzenbiochemie, Abteilung Sekundärstoffwechsel, Weinberg 3, D-06120 Halle (Saale), Germany. tfester@ipb-halle.de
Hause
Bettina
B
Schmidt
Diana
D
Halfmann
Kristine
K
Schmidt
Jürgen
J
Wray
Victor
V
Hause
Gerd
G
Strack
Dieter
D
D002240:Carbohydrate Sequence; D002338:Carotenoids / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D002475:Cellobiose / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D003512:Cyclohexanones / Q000737:chemistry / Q000302:isolation & purification; D003998:Dicarboxylic Acids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D005658:Fungi / Q000254:growth & development*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D059828:Plant Cells; D018517:Plant Roots / Q000378:metabolism* / Q000382:microbiology / Q000648:ultrastructure; D010944:Plants / Q000378:metabolism* / Q000382:microbiology; D011090:Polyenes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013057:Spectrum Analysis; D013559:Symbiosis
D003512:Cyclohexanones; D003998:Dicarboxylic Acids; D011090:Polyenes; C458518:blumenol C cellobioside; C458517:mycorradicin; D002475:Cellobiose; D002338:Carotenoids