OBJECTIVETo explore the molecular mechanism of continuous monoculture problem by constructing the cDNA libraries of continuous monoculture Rehmannia glutinosa.

METHODTo use the suppression subtractive hybridization (SSH) technique to construct the forward and reverse subtractive cDNA libraries of continuous monoculture R. glutinosa to adopt blue-white colony screening and PCR to detect the positive clones which would be sequenced and analyzed by bioinformatics.

RESULTThe subtracted cDNA libraries of continuous monoculture R. glutinosa. were successfully constructed, and the result showed that the forward and reverse subtracted libraries obtained 300 positive clones, respectively. The forward and reverse libraries got different ESTs, and produced 232 (forward library) and 214 (reverse library) unique ESTs by sequencing. Based on homology search of BLASTX and BLASTN in NCBI, 200 and 195 of unique ESTs were homologous to known genes in the forward and reverse libraries, respectively. Categories of orthologous group (COG) showed that the forward and reverse libraries got 60 and 61 ESTs with the corresponding gene annotation, involving 21 metabolic pathways.

CONCLUSIONThe information of differential expression genes in continuous monoculture R. glutinosa, and their functional annotation of differentially expressed genes indicate that continuous monoculture has a profound effect on expression of the genes in R. glutinosa. Furthermore, the research analyzed several key genes in response to replant problem, which provided a foundation for revealing the molecular mechanism of continuous monoculture R. glutinosa.