Intermediates accumulation and inhibition sites of carpropamid in the melanin biosynthesis pathway of Pyricularia oryzae
Kurahashi, Y.; Araki, Y.; Kinbara, T.; Pontzen, R.; Yamaguchi, I.
Journal of Pesticide Science 23(1): 22-28
ISSN/ISBN: 1348-589X DOI: 10.1584/jpestics.23.22
Carpropamid ((1RS,3SR)-2,2-dichloro-N-(1-(4-chlorophenyl)ethyl)-l-ethyl-3-methylcyclopropanecarboxamide) strongly inhibited pigmentation in shaking culture as well as in agar plate culture of Pyricularia oryzae and Verticillium dahliae. White crystals were isolated from the extract of the cultures of wild type strains of P. oryzae and V. dahliae treated with carpropamid. Analytical data of the crystals obtained from a spot at Rf 0.36 on the TLC plates coincided with those of scytalone. A large amount of scytalone and a small amount of vermelone accumulated in the culture treated with 10 mug/ml of carpropamid, while 2-hydroxyjuglone was not detected in these analyses. When scytalone was added to the shaking culture of albino mutants of P. oryzae (P2-alb), it promptly disappeared from the culture and the culture was pigmented to light brown. But scytalone remained in the culture if treated with carpropamid. Scytalone and vermelone administered beside the colony of P2-alb on the agar plates were converted to black pigments but the pigmentation was inhibited by carpropamid. These results suggest that carpropamid inhibits dehydration of scytalone and vermelone in the fungal melanin biosynthesis.