Phosphatidylcholine is a type of phospholipids which is known to serve as structural
element of membranes and involves in several physiological activities of organisms, including
plants , In addition, phosphatidylcholine has been recently suspected to play a role in the
interaction between fungi and phytoalexins in the plant It is therefore interesting to utilize this
type of phospholipids in assessing phytoalexin toxicities. In the previous study it was also found
that addition of phosphatidylcholine to media reduced the inhibitory effects of pisatin against
several fungi .The aim of this study was to determine the effect of phosphatidylcholine on the
sensitivity of fungi to a phytoalexin of loquat (Eryobotria japonica), aucuparin, and two
fungicides, some of the results presented here had been briefly reported elsewhere .
Eight fungi (Ascochyta pisi, Monilinia fructicola, Pestalopsis funereal, Rhizoctonia oryzae,
Rhizoctonia solani AG-1, Rhizoctonia solani AG-2, Sclerotium hydrophilum and Sclerotium
oryzae-sativae) used in this experiment were isolated from their host plants and cultured on
potato sucrose agar (PSA) at 25 C in the dark and transferred periodically to fresh medium. The
synthetic aucuparin was kindly provided by Dr. Watanabe, Sumitomo Chemical Co., Ltd.
Phosphatidylcholine (Type IV-S, from soybean) was purchased from Sigma Chemical Company,
St. Louis, M.O. Validamycin (Validamycin) and pencycuron (Monoceren) were kindly
provided by Takeda Chemical Ind., Ltd. And Bayer AG., GB., respectively.
The influence of phosphatidylcholine on the antifungak activity of aucuparin was tested
by using a spore germination inhibition test as described by Kiraly et al. with pathogenic and
non-pathogenic fungi of E. japonica. Ethanolic solutions of pure aucuparin and
phosphatidylcholine was added to water so that the concentration of ethanol was 2 % and the
concentrations of aucuparin and phosphatidylcholine were 100 µg/ml, respectively. The agar
block containing spores wasincubated at 20-25 C in moist chamber and the spore germination
was counted under light microscope when germination rate of control rate (2% thanol solution)
was over than 80%. The data in table indicated that aucuparin showed higher toxicity toward non
pathogenic fungi (A. pisi and M. fructicola) than toward the pathogenic fungus (P. funereal) of the
loquat. It was also found that the antifungal activity of aucuparin was weaker
element of membranes and involves in several physiological activities of organisms, including
plants , In addition, phosphatidylcholine has been recently suspected to play a role in the
interaction between fungi and phytoalexins in the plant It is therefore interesting to utilize this
type of phospholipids in assessing phytoalexin toxicities. In the previous study it was also found
that addition of phosphatidylcholine to media reduced the inhibitory effects of pisatin against
several fungi .The aim of this study was to determine the effect of phosphatidylcholine on the
sensitivity of fungi to a phytoalexin of loquat (Eryobotria japonica), aucuparin, and two
fungicides, some of the results presented here had been briefly reported elsewhere .
Eight fungi (Ascochyta pisi, Monilinia fructicola, Pestalopsis funereal, Rhizoctonia oryzae,
Rhizoctonia solani AG-1, Rhizoctonia solani AG-2, Sclerotium hydrophilum and Sclerotium
oryzae-sativae) used in this experiment were isolated from their host plants and cultured on
potato sucrose agar (PSA) at 25 C in the dark and transferred periodically to fresh medium. The
synthetic aucuparin was kindly provided by Dr. Watanabe, Sumitomo Chemical Co., Ltd.
Phosphatidylcholine (Type IV-S, from soybean) was purchased from Sigma Chemical Company,
St. Louis, M.O. Validamycin (Validamycin) and pencycuron (Monoceren) were kindly
provided by Takeda Chemical Ind., Ltd. And Bayer AG., GB., respectively.
The influence of phosphatidylcholine on the antifungak activity of aucuparin was tested
by using a spore germination inhibition test as described by Kiraly et al. with pathogenic and
non-pathogenic fungi of E. japonica. Ethanolic solutions of pure aucuparin and
phosphatidylcholine was added to water so that the concentration of ethanol was 2 % and the
concentrations of aucuparin and phosphatidylcholine were 100 µg/ml, respectively. The agar
block containing spores wasincubated at 20-25 C in moist chamber and the spore germination
was counted under light microscope when germination rate of control rate (2% thanol solution)
was over than 80%. The data in table indicated that aucuparin showed higher toxicity toward non
pathogenic fungi (A. pisi and M. fructicola) than toward the pathogenic fungus (P. funereal) of the
loquat. It was also found that the antifungal activity of aucuparin was weaker
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