Abstract：Flo8 is a key transcription factor at the downstream of cAMP signal pathway and plays an important role in fungal development. In this experiment, in order to clarify the function of transcription factor Flo8 and cAMP singal pathway in regulating the pathogenicity of Setosphaeria turcica, the genes encoding transcription factor Flo8 was cloned and the expression pattern of the gene was analyzed during the development of infective structures and the early stage of infecting the host. The homologous search was carried out in the database of S. turcica using the Candida albicans Flo8 amino acid sequence as a probe. The gene encoding the transcription factor Flo8 was identified by PCR. The structural characteristics of the gene and protein were analyzed through GSDS, ProtParam, SOMPA and SMART software, respectively. Subcellular localization of protein was analyzed by WoLF PSORT online software. Quantitative real-time PCR (qRT-PCR) was used to analyze the gene expression patterns. The results showed that there was a protein sequence containing the conserved domain of LisH which belonged to the typical FLO8 protein, and its coding gene was named StFlo8. The total length of the gene was 2 384 bp, and that of the cDNA was 2 037 bp, this gene contained 6 introns and 7 exons, encoding 678 amino acids. The results of expression pattern analysis showed that, compared with the mycelial period, the expression level of StFlo8 was significantly decreased in the conidia and germ tube period, and was significantly higher in appressorium and invade mycelial period, reaching more than 4 times of that in the mycelia. During the interaction of S. turcica with the susceptible host, the expression of StFlo8 was down-up-down regulated, and reached the highest level at 18 h after inoculation, which was as about twice as that of the beginning of inoculation. The results indicated that StFlo8 was involved in the regulation of appressorium development and infected mycelial formation. The results provide a theoretical basis for the further study of the function of StFlo8 gene and the infection mechanism of S. turcica.
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