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Influence of abscisic acid and the abscisic acid biosynthesis inhibitor, norflurazon, on interactions between Phytophthora sojae and soybean (Glycine max)

journal contribution
posted on 1999-10-01, 00:00 authored by K L McDonald, David CahillDavid Cahill
A comparison was made of the effects of abscisic acid (ABA) and the ABA biosynthesis inhibitor, norflurazon on the interaction between soybean leaves and Phytophthora sojae. Inoculation of leaves of cv. Harosoy resulted in a compatible interaction typified by the presence of spreading, water soaked lesions with ill-defined margins while inoculation of cv. Haro 1272 resulted in an incompatible interaction with lesions restricted to the inoculation site. Activity of phenylalanine ammonia lyase (PAL) slowly increased in the compatible interaction but in the incompatible interaction there was a rapid rise in activity within 8 h after inoculation. When Haro 1272 plants were treated with ABA the normally incompatible interaction with race 1 was changed to what resembled a compatible interaction and activity of PAL was reduced to control levels. There was no visible effect on the compatible combination. In contrast when plants of cv. Harosoy were treated with norflurazon the normally compatible interaction with race 1 was changed to that which resembled an incompatible interaction and PAL activity increased to high levels rapidly. There was no effect of norflurazon on the incompatible interaction of cv. Haro 1272 with race 1. Stomata on leaves of cv. Harosoy treated with norflurazon closed within 2 h of inoculation resembling the response of stomata in normal incompatible interactions but not compatible interactions where stomata remained open. On leaves of cv. Harosoy treated with norflurazon at sites 3 and 20 mm from the inoculation point stomata also closed. These results extend and confirm the idea that ABA is a molecule that may regulate the outcome of the interaction between soybeans and P. sojae.



European Journal of Plant Pathology






651 - 658


Springer Netherlands [Kluwer Academic Publishers]


Dordrecht, The Netherlands





Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

1999, Kluwer Academic Publishers