Ia. Dubery et V. Slater, INDUCED DEFENSE RESPONSES IN COTTON LEAF-DISKS BY ELICITORS FROM VERTICILLIUM-DAHLIAE, Phytochemistry, 44(8), 1997, pp. 1429-1434
Cotton (Gossypium hirsutum) leaf tissue responded with symptoms of chl
orosis and necrosis to treatment with heat-released soluble cell-wall
fragments from Verticillium dahliae. The induction of defence response
s in leaf disks by the elicitor led to increased synthesis of anti-fun
gal lasinilene and cadalene stress metabolites, as well as the rapid d
eposition of phenolic polymers in the lignin fraction. The coordinated
induction and accumulation of chitinases and 1,3-beta-glucanases were
observed following elicitation; selective low pH extracts of pathogen
esis related-proteins revealed a bi-phasic defence hydrolase response
that reached a peak within 12 hr, followed by a gradual increase up to
120 hr. Electrophoretic analysis and enzyme staining revealed differe
nces in constitutive and inducible proteins. Three acidic isozymes of
chitinase with isoelectric points in the range 3.7-4.2, but only one b
eta-1,3-glucanase isozyme with an isoelectric point of 4.5 were found
in the intercellular fluid. The results obtained indicate that the eli
citation of cotton leaf disks by V. dahliae derived signal molecules e
xhibits some properties of a multicomponent dynamic system where diffe
rent protective mechanisms have complementary roles in the overall exp
ression of the defence response. Copyright (C) 1997 Elsevier Science L
td.