Hs. Mayton et al., CORRELATION OF FUNGICIDAL ACTIVITY OF BRASSICA SPECIES WITH ALLYL ISOTHIOCYANATE PRODUCTION IN MACERATED LEAF TISSUE, Phytopathology, 86(3), 1996, pp. 267-271
Brassica species were tested for production of volatile fungicidal com
pounds from macerated green leaf tissue. Tissue (10, 20, and 40 g) of
one cultivar each of six Brassica species was assayed for inhibition o
f Fusarium sambacinum. Only cultivars of B. nigra and B. juncea suppre
ssed radial growth (>50% inhibition of control). Plant introduction ac
cessions (PIs) of B. juncea, B. carinata, B. nigra, and B. napus were
screened for suppression of F. sambucinum. Only B, nigra, B. juncea, a
nd B. carinata PIs had suppressive activity, but activity varied among
PIs within these species. The concentration of allyl isothiocyanate (
AITC), a breakdown product of allyl glucosinolate, in leaf tissue was
measured using gas chromatography. AITC was detected in PIs of B. nigr
a, B. juncea, and B. carinata. Radial growth of F. sambucinum was nega
tively correlated (P < 0.05) with AITC concentrations emitted from Bra
ssica leaf tissue. All Brassica PIs with AITC concentrations greater t
han 0.10 mg/g of leaf tissue were suppressive to F. sambucinum in radi
al growth assays. Growth of five other plant pathogenic fungi was also
suppressed by a B. juncea cultivar that contained high concentrations
of AITC.