Identification of up-regulated transcripts during Pleurotus ostreatus primordium stage and characterization of PoALDH1.

In order to isolate the differentially expressed genes in the primordium stage of Pleurotus ostreatus, the SSH cDNA library was constructed using the cDNA from dikaryotic mycelium stage as a driver and the cDNA from primordium stage as a tester. There were 423 significantly differently expressed clones among 2055 positive clones after three times of reverse Northern blot differential screening. After the repeated sequences being removed, 46 genes were identified which were putatively involved in cell rescue and defense, energy metabolism, transcription and protein regulation, membrane proteins, and signal transduction; 18 genes encoding hypothetical proteins with unknown function; 5 genes without any homology. PoALDH1 and its full-length cDNA sequence were cloned using the Aldehyde dehydrogenase EST isolated from the library. The amino acid sequence of PoALDH1 contains conservative glutamic acid and cysteine residues active sites of aldehyde dehydrogenase family. When exposed to different concentrations of sodium chloride, the mycelium growth was inhibited and the expression level of PoALDH1 was significantly higher than that of the control one, which indicated that PoALDH1 may have the ability to relieve salt stress. The results of this study will provide useful information for isolating growth and development related genes of P. ostreatus.