Cloning and functional analysis of scytalone dehytratase gene in Exserohilum turcicum

Genemonic DNA and cDNA homologous fragments of the scd(scytalone dehydratase) gene were obtained by polymerase chain reaction(PCR)amplification from degenerated primer sets designed on the basis of the conserved amino acid regions of scytalone dehydratase and polyketide synthase domains from others fungis. The completed cDNA sequence of scd in E. turcica was obtained by the method of SMART-RACE and 3′RACE. There is one open reading frame composed of 181 codons and two deduced introns of 50 and 78 nucleotides in the scd gene. The deduced amino acid sequence of the scd showed high similarity to the amino acid sequence of scytalone dehydratase from Bipolaris oryzae. Carpropamid,a specific inhibitor,could inhibit the conidial germination and appressorium production of E. turcica within 24h treatment but no evident inhibitory effect after 24h . The experimental results also suggested that E. turcica could not penetrate the surface of corn tissue or increase in the corn tissue. It was conclusion that scd gene might play an important role in melanin biosynthetic pathway and pathogenicity of E. turcica.