IDENTIFICATION OF DIFFERENTIALLY EXPRESSED SEQUENCES FROM TETRAPLOID ISATIS INDIGOTICA ROOTS TREATED BY FUSARIUM SOLANI

Abstract

Isatis indigotica Fort. is a widely used Chinese medicinal herb. Root rot disease, induced by Fusarium solani f.sp glyeine, causes severe yield losses of this crop in northern China. In order to gain an insight into the response mechanism of tetraploid I. indigotica to F. solani infection, a subtractive suppression hybridization (SSH) cDNA library was constructed. SSH was performed with cDNA from I. indigotica root inoculated by water as the “driver” and by F. solani as the “tester”. A total of 160 clones in the SSH library were sequenced and found to represent 25 unigenes. BLASTX results reveal that 19 cDNAs had significant sequence similarity with known sequences in the NCBI database. The identified cDNAs encode proteins involved in cellular processes such as primary metabolism, signal transduction, defense and responses to pathogen, stress and transcription. Eight genes among those identified by the screening were selected for semi-quantitative RT-PCR to confirm the SSH result. The diversity of the putative functions of these genes indicates that infection of F. solani results in a complex response in I. indigotica plants.