Abstract

The gene differential expression of Phytophthora sojae during early stage (0 to 7 h) of sporangium formation was studied by differential display reverse transcription polymerase chain reaction (DDRT-PCR) in the present study. Thirty out of 78 primer combinations were selected and 90 stable differential bands were obtained. Thirty-nine positive differential fragments were found in the experiments by using the reverse northern blot, in which 36 sequences of differential fragments were obtained after sequencing. Homology search and analysis were tested by BLASTX in the P. sojae genome database. The results showed that 23 fragments had significant similarities with proteins in P. sojaegenome database, 15 of which matched with the known functional proteins involved in metabolism, cellular processes, and signal transduction processes. Data mining and bioinformatics analysis on 4 fragments which redundancy was greater than 5 showed that sequence AR₁₅-258 had a very high expression level in Phytophthora mycelium, which may be related to mycelium infection or hunger; AR₁₀-263 and GR₁-304 were only found in Phytophthora, which might be unique expression in this genus. The analysis and research on important regulatory genes controlling sporangium formation of P. sojae was a foundation for studying of key genes controlling growth and development of P. sojae.

Key words: Phytophthora sojae, sporangium formation, mRNA differential display, differential fragments.