Melanin biosynthesis and its biological function as heat persistence in plantpathogens and other fungi

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12660049
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 植物保護
• Research Institution: TOYO UNIVERSITY
• Principal Investigator: FUJIMURA Makoto TOYO UNIVERSITY, LIFE SCIENCE, PROFESSOR, 生命科学部, 教授 (50297735)
• Project Period (FY): 2000 – 2001
• Keywords: melanin / Pyricularia / polyketide synthase / Neurospora / sexual cycle

Research Abstract

Melanin biosynthesis inhibitors, such as carpropamid and diclocymet, affected conidial formation in Pyricularia oryzae. In addition, the conidia on the medium containing fungicides increased the sensitivity to heat treatment. Reduced heat persistence induced by fungicides was not observed in fungicide resistant isolates, suggesting correlation between melanization and heat persistence. In Neurospora crassa, black pigment develops in sexual organs such as perithecia and ascospore, and ascospore showed high resistance to heat treatment. On the other hand, ascospore of the per-1 mutant, melanin deficient strain, was sensitive to heat treatment. The wild-type strain treated by tricyclazole accumulated 2-HJ, a shunt product of DHN-melanm. The DHN-melanin synthesis genes, such as PKS, SDH, and HNR, were clones and characterized. The per-1 mutant strain transformed with the wild-type PKSgene recovered the ability of melanin biosynthesis and heat resistance. The mutation within the PKSgene of the per-1 mutant strain was identified as ^<210>arg to stop codon. The transcription of melanin biosynthesis genes was induced by fertilization not by nutrient starvation in sexual cycle of N.crassa.