title: A saponin correlated with variable resistance of Barbarea vulgaris to the diamondback moth Plutella xylostella.
abstract: Two types of Barbarea vulgaris var. arcuata, the G-type and the P-type, differed in resistance to larvae of the diamondback moth (DBM) Platella xylostella. Rosette plants of the G-type were fully resistant to the DBM when grown in a greenhouse or collected in the summer season, but leaves collected during the late fall were less resistant, as previously found for flea beetle resistance. The P-type was always susceptible. Extracts of resistant leaflets inhibited larval growth in a bioassay, and a growth-inhibiting fraction was isolated by activity-guided fractionation. A triterpenoid saponin (1) was isolated from this fraction and identified as 3-O-beta-cellobiosyloleanolic acid from spectroscopic data and analysis of hydrolysis products. The decrease in resistance of the G-type in the fall was correlated with a decrease in the level of 1, from 0.6-0.9 to < 0.2 micromol/g dry wt. Compound 1 was not detected in the susceptible P-type. We conclude that 1 is correlated with the variable resistance of B. vulgaris foliage to the DBM.
authors.affiliation: Chemistry Department, Royal Veterinary and Agricultural University Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark. nia@kvl.dk
authors.forename: Niels
authors.initials: N
authors.lastname: Agerbirk
authors.forename: Carl E
authors.initials: CE
authors.lastname: Olsen
authors.forename: Bo M
authors.initials: BM
authors.lastname: Bibby
authors.forename: Hanne O
authors.initials: HO
authors.lastname: Frandsen
authors.forename: Lea D
authors.initials: LD
authors.lastname: Brown
authors.forename: Jens K
authors.initials: JK
authors.lastname: Nielsen
authors.forename: J Alan A
authors.initials: JA
authors.lastname: Renwick
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D031216:Barbarea / Q000737:chemistry*; D001681:Biological Assay; D005247:Feeding Behavior; D007814:Larva / Q000254:growth & development; D009036:Moths / Q000254:growth & development*; D009828:Oleanolic Acid / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000494:pharmacology*; D010572:Pest Control, Biological; D018515:Plant Leaves / Q000737:chemistry; D012503:Saponins / Q000302:isolation & purification / Q000494:pharmacology*; D012621:Seasons
chemical_list: C479463:3-O-beta-cellobiosyloleanolic acid; D012503:Saponins; D009828:Oleanolic Acid