A saponin correlated with variable resistance of Barbarea vulgaris to the diamondback moth Plutella xylostella.
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.
Agerbirk
Niels
N
Chemistry Department, Royal Veterinary and Agricultural University Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark. nia@kvl.dk
Olsen
Carl E
CE
Bibby
Bo M
BM
Frandsen
Hanne O
HO
Brown
Lea D
LD
Nielsen
Jens K
JK
Renwick
J Alan A
JA
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
C479463:3-O-beta-cellobiosyloleanolic acid; D012503:Saponins; D009828:Oleanolic Acid