The biosynthesis of allelopathic di-C-glycosylflavones from the roots of Desmodium incanum (G. Mey.) DC

• Published in: Organic & biomolecular chemistry Vol. 13; no. 48; pp. 11663 - 11673
• Main Authors: Hao, Bing, Caulfield, John C., Hamilton, Mary L., Pickett, John A., Midega, Charles A. O., Khan, Zeyaur R., Wang, Junru R., Hooper, Antony M.
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 01.01.2015
• Subjects: Allelopathy; Chemistry; Chemistry, Organic; Fabaceae - chemistry; Flavones - biosynthesis; Flavones - chemistry; Glycosylation; Molecular Structure; Physical Sciences; Plant Roots - chemistry; Science & Technology; Spectrometry, Mass, Electrospray Ionization; STRIGA-HERMONTHICA; WESTERN KENYA; SPP; EXUDATE; PUSH-PULL TECHNOLOGY; INTERCROPS; FLAVONOIDS; UNCINATUM; ISOSCHAFTOSIDE; IDENTIFICATION
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c5ob01926e

The allelopathic root exudate of the drought-tolerant subsistence cereal intercrop D. incanum, protecting against the parasitic weed Striga hermonthica, comprises a number of di-C-glycosylflavones specifically containing C-glucosyl, C-galactosyl and C-arabinosyl moieties. Here we demonstrate that the biosynthesis of all compounds containing a C-glucose involves C-glucosylation of 2-hydroxynaringenin with subsequent C-galactosylation, C-glucosylation or C-arabinosylation. In addition, the crude soluble enzyme extract converts two fluorinated 2-hydroxyflavanone analogues to corresponding mono-and di-C-glycosylflavones demonstrating that some differences in C-ring substitution can be tolerated by the plant enzymes. Elucidating the biosynthesis of these C-glycosylflavones (CGFs) has the potential to open up opportunities for transferring the enzymic and genetic basis for the S. hermonthica inhibiting allelopathic trait to food crop plants.