Abstract：G protein coupled receptors (GPCRs) constitute the biggest transmembrane receptor superfamily which mediates the signal transduction and generally exists in animals, plants and microbes. The genes encoding GPCRs and their genomic locations were obtained and identified by searching the genome database of Setosphaeria turcica with the HMMER 3.0 software based on hidden markov model. The MEGA 5.0 software was employed to analyze the systemic evolution. Genetic structure conservative sites of GPCRs were analyzed online through generalized sample data system (GSDS), InterPro and SMART. It was finally confirmed that there were 9 GPCR genes in the genome of S. turcica. Three of them belonged to putative nitrogen sensors, while there were 2 pheromone receptors and 2 carbon sensors respectively. And the remaining 2 were classified as cyclic adenosine monophosphate (cAMP) receptor-like protein and Fungal opsin. GPCR superfamily genes distributed in the genome randomly, and its structure was complicated. All members consisted of N-terminal, seven transmembrane domains, three intracellular loops, three extracellular loops and C-terminal. Each transmembrane domain comprised 20 to 25 amino acids. Finally, relative expression quantities of GPCR genes in the invasive structure formation process were detected by using the qRT-PCR technology. Transcriptional pattern analysis showed that in appressorium mature period 12 hours post inoculation (hpi), all genes were significantly downregulated (P＜0.05). Except StRtc1 and Stfdd123, trends of other genes all showed a downregulated/flat (3 hpi)-upregulated (6 hpi)- downregulated (12 hpi)-upregulated (24 hpi). Especially, they were significantly upregulated (P＜0.05) during the invasive mycelium formation (24 hpi). In appressorial formation period (6 hpi), only StSte2p and StRtc2 significantly upregulated. The expression levels of StRtc1 and Stfdd123 in each stage were not significant or significantly downregulated. This study provides a theoretical basis for in-depth analysis about the function of GPCR superfamily in plant pathogenic fungi.
