BIOTIC AND ABIOTIC ELICITATION OF PHYTOALEXINS IN LEAVES OF GROUNDNUT(ARACHIS-HYPOGAEA L)

Groundnut leaves (cultivar TMV2) infected with the fungal pathogens, C ercospora arachidicola, Phaeoisariopsis personata and Puccinia arachid is accumulated 1830, 664 and 162 nmol phytoalexins g(-1) fresh wt., re spectively, 4 weeks after inoculation, whereas leaves infested with Fr ankliniella sp. for the same period contained 1.25 nmol phytoalexins g fresh wt. Spraying abraded leaves with salicylic acid (0.01 M) result ed in the accumulation of 1270 nmol phytoalexins g(-1) fresh wt. 120 h after treatment and irradiation of abaxial leaf surfaces with u.v. li ght (254 nm) for 48 h and incubation in the dark for a further 96 h ca used the accumulation of 393 nmol phytoalexins g(-1) fresh wt. Compoun ds with u.v. spectra corresponding to isoflavanones were almost exclus ively synthesized in response to abiotic elicitors but in leaves infec ted with fungal pathogens formononetin, daidzein, and medicarpin were also present, though as minor components. (C) 1996 Academic Press Limi ted.