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STOMATAL BEHAVIOR OF AVENA SATIVA TREATED WITH TWO PHYTOTOXINS, VICTORIN AND FUSICOCCIN

1972; Wiley; Volume: 59; Issue: 2 Linguagem: Inglês

10.1002/j.1537-2197.1972.tb10071.x

1537-2197

Neil C. Turner,

Plant pathogens and resistance mechanisms

The transpiration and stomatal behavior of blight‐susceptible and blight‐resistant oats (Avena sativa L.) were followed after treatment with victorin, the host‐specific toxin of Helminthosporium victoriae , and fusicoccin, the toxin produced by Fusicoccum amygdali . Victorin, at 0.012 units/ml and greater, significantly decreased the transpiration of the blight‐susceptible variety in 3 hr, but had no effect on the transpiration of the blight‐resistant variety. The stomatal resistance, measured with a ventilated diffusion porometer, showed that the decrease in transpiration was caused by stomatal closure; the greater the concentration of victorin the earlier the stomata closed. At high concentrations of victorin the stomata reopened in the blight‐susceptible variety, and partial stomatal closure was observed in the resistant variety. Inactivated toxin had no effect on the stomata of either oat variety. When fusicoccin and victorin were compared under the same environmental conditions, victorin closed the stomata of the blight‐susceptible leaves, whereas fusicoccin opened the stomata in both the blight‐susceptible and resistant leaves. It is concluded that the two toxins differ in their effects on the guard cells; their possible modes of action are discussed.