Pg. Zhang et al., GLIOCLADIUM ROSEUM REDUCES PHYSIOLOGICAL-CHANGES ASSOCIATED WITH INFECTION OF BLACK SPRUCE SEEDLINGS BY BOTRYTIS-CINEREA, Canadian journal of plant pathology, 18(1), 1996, pp. 7-13
Black spruce (Picea mariana) seedlings were treated with Gliocladium r
oseum (5 x 10(7) conidia/mL) or with water, kept in high relative humi
dity (RH) for 24 h, challenge-inoculated with Botrytis cinerea (5 x 10
(5) conidia/mL) or with water, and returned to high RH for 24 h, entir
ely at 20-21 degrees C. The seedlings were subsequently kept in a grow
th chamber and were evaluated at 2-4 day intervals for sporulation pot
ential of B. cinerea, electrolyte leakage, chlorophyll content, and ph
otosynthetic rate. After 6-15 days, B. cinerea sporulated in 56-63% of
needles and produced 29.3-40.5 x 10(3) conidia/needle in plants treat
ed with water and challenged with the pathogen, whereas in plants trea
ted with G. roseum prior to inoculation with B. cinerea sporulation in
cidence was only 1-8% and spore production was 0.5-6.6 x 10(3) conidia
/needle. The pathogen did not sporulate in the water checks or in seed
lings treated with G. roseum and water. Electrolyte leakage, chlorophy
ll content, and photosynthetic rate did not differ significantly among
seedlings treated with water only, with G. roseum and water, or with
G. roseum and B. cinerea, and ranged respectively from 5.6 to 13.3% (r
elative to leakage after the tissues were heat killed), 9.3 to 10.6 mg
chlorophyll/g dried shoot, and 8.6 to 15.8 mu mol CO2 . m(-2). s(-1).
In seedlings treated with water and B. cinerea, electrolyte leakage i
ncreased to 47-51% after 9 days, chlorophyll declined from 9.5 to 5.1
mg/g dried shoot during 2 to 15 days, and photosynthetic rate fell fro
m 9.0 to 0.4 mu mol . m(-2). s(-1) at 2 to 15 days after inoculation.
We conclude that G. roseum effectively suppressed B. cinerea in seedli
ngs and prevented significant changes in electrolyte leakage, chloroph
yll level, and photosynthetic rate associated with gray mold, but it d
id not affect these Variables when the pathogen was not present.