Identification And Analysis Of Phytophthora Sojae Genes Upregulated During Early Stages Of Oosporogenesis

Phytophthora sojae as a kind of soil spread plant pathogen have a great harm on soybean production.The present study show that the pathogenicity of the pathogens is variable, so new disease-resistant varieties will have failure of resistant infestation for the emergence of new pathogenic races of Phytophthora sojae. Therefore, control of Phytophthora sojae is always an important problem of soybean production. It is one of the most important premise that understanding the molecular mechanism of growth. Transcription factors play an important regulatory role in life of eukaryotes. The key to clarify the fungus growth and pathogenicity is to understand gene expression and regulation in the genome level. Research of transcription factor will help to understand the fungus gene regulatory networks and interactions in the cell.Differences in gene expression during the early specific sexual development of Phytophthora sojae were assessed using a suppression subtractive hybridization (SSH) approach to explore molecular mechanisms involved in oospore formation.Of the183sequences selected by the dot hybridization analysis,41putative unigenes were identified that exhibited high expression in the oospore formation stage.These sequences are predicted to encode proteins involved in energy synthesis, protein synthesis, cell signal transduction, cell-wall formation, transcriptional regulation and so on. Eleven clones were selected using RT-PCR examination based on the results of dot-blot screens. Eight of the selected genes were expressed only during oospore formation stage, whereas the other three genes, Myb DNA-binding domain gene, hypothetical protein gene and Tubulin-tyrosine ligase gene, were detected at the zero time point.A gene, PsMybl, encoding a putative transcription factor that transcription regulation with sexual development was cloned from PS26. Results showed that the gene contains2introns, which located in the downstream of initiation codon bases in469bp and358bp and their sizes were73bp and78bp respectively. The predicted amino acid sequence of PsMybl was composed by605amino acid. The gene has two introns located in around358bp and498bp downstream of start codon. They do not have high homology in the peptide sequences among plants by the cluster of PsMybl. One conservative region of PsMyb1is SHLQKYR(Ser-His-Leu-Gln-Lys-Tyr-Arg). PsMybl function was analysed by transcriptional gene silencing technology. The relative expression level of PsMyb1in silence mutants of PsMybl were down.Oospore productions of wild-type isolates were from260to270, and oospore production of silence mutants of PsMyb1were from10to30. The results suggeste that P.sojae maybe require PsMybl for its sexual development.