Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Effect of Partially Purified Components of Zoospores and Mycelia of Phytophthora infestans on Uptake of 3H-Leucine by Potato Tuber Disks
Norio NISHIMURAKohei TOMIYAMANoriyuki DOKE
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1980 Volume 46 Issue 1 Pages 1-6

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Abstract

The zoosporial component of Phytophthora infestans, which was previously reported to cause reduction of 3H-leucine uptake by potato tuber disks, was partially purified. Precipitate (A-fraction) was obtained by homogenizing zoospores with acetate buffer at pH 4.5 and centrifuging at 20, 000×g, and the A-fraction was suspended in borate buffer at pH 8.8, boiled for 1 hr and then centrifuged at 20, 000×g, giving the precipitate (B-fraction) and supernatant (C-fraction). Ten ml of 10 mM tris-HCl buffer containing 1 mM CaCl2 at pH 7.4 was used to suspend A and B-fraction. The buffer was used as a control. A, B and C fractions obtained from 5-6×106 zoosprores reducted uptake of 3H-leucine by the tuber disks of potato cv. Rishiri, but the inhibition rates caused by these fractions differed markedly. However, very high correlation was found between inhibition rates of 3H-leucine uptake and sugar contents of these fractions. There was no difference in the inhibition rates between the zoosporial components of incompatible and compatible races, when the activities were expressed in terms of the sugar contents. The mycelial components of P. infestans extracted by the modified method of Lisker and Kuc which was used to extract phytoalexin elicitor from that of P. infestans, also had the same effect as the zoosporial components (A, B, and C-fraction) on 3H-leucine uptake by the disks. C-fraction containing 15μg of sugar per ml sufficed to inhibit 3H-leucine uptake at the maximum rate, and the maximum rate of inhibition was attained within 2 hr after the zoosporial component (C-fraction containing 30μg sugar/ml) was administered to the disks.

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© The Phytopathological Society of Japan
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