Using a Suppression Subtractive Library-Based Approach to Identify Non-Heading Chinese Cabbage Genes Up-Regulated in Early Response to Elicitor PB90

Monitoring expression at the transcriptional level is the first essential step for the functional analysis of plant genes. Genes-encoding proteins directly involved in early response to elicitor constitute only a small fraction of all the genes affected by elicitor. Transcriptional responses to various elicitors have been extensively studied in different plants including Nicotiana and Arahidopsis thaliana; however, corresponding data aren't available for non-heading Chinese cabbage. To address this problem, we describe a suppression subtractive library-based approach to isolate the plant's ESTs up-regulated in the early induction/execution of the HR induced by elicitor PB90 from Phytophthora boehmeriae. According to their putative identification in BLAST searches against the three genome databases, 70 up-regulated genes were classified into 9 parts: some aspect of primary ‘metabolism’ or ‘energy’ production; ‘protein synthesis’ or ‘protein fate’; cellular communication/signal transduction mechanism; cell fates including Beclin, SPT1, and SPT2; HLA-B and AGO1 which participate in transcription; cellular transport and hypothetical proteins or proteins for which a function has yet to be determined. Seven selected genes such as Beclin, thioredoxin, HLA-B, MAP3K, SPT1, SPT2, and AGO1 were up-regulated induced by PB90, suggesting that the genes may play an important role in PB90-triggered HR.