Cf. Hodges et Da. Campbell, Endogenous ethane and ethylene of Poa pratensis leaf blades and leaf chlorosis in response to biologically active products of Bipolaris sorokiniana, EUR J PL P, 105(8), 1999, pp. 825-829
Infection of Poa pratensis leaf blades and callus tissue by Bipolaris sorok
iniana increases the production of ethylene and ethane. The ethylene is res
ponsible for most of the chlorosis that occurs during pathogenesis. The non
selective toxin(s) produced by B. sorokiniana is known to disrupt membranes
and to damage chlorophyll, but it is not known whether it can induce an in
crease in ethylene or ethane. Research was initiated to determine the effec
t of a biologically-active extract of B. sorokiniana on the endogenous ethy
lene and ethane of intact P. pratensis leaf blades and on subsequent develo
pment of chlorosis. The extract did not increase endogenous ethylene of tre
ated leaves, but it was associated with an increase in endogenous ethane be
tween 24 and 96 h after treatment. Chlorophyll loss occurred 96 h after tre
atment and persisted for the duration of the study (168 h). The chlorophyll
content of treated leaf blades ranged from 72% to 80% of control leaf blad
es. The observations suggest that the extract of B. sorokiniana can induce
chlorophyll loss from treated leaf blades independent of an increase in end
ogenous ethylene by directly damaging chloroplasts with a concurrent releas
e of ethane. The ethane is believed to be a by-product of pathogenesis.