Abstract
Leaf cells are reprogrammed to protonemal apical stem cells within 24 hours after leaf excision in Physcomitrella patens. To characterize the molecular events during this process, we undertook Digital Gene Expression analysis by SOLiD system. Time course expression data for 35,937 annotated genes were obtained from the samples collected during 0 to 24 hours after leaf excision.
After statistical filtering, 3,530 genes were found as the differentially expressed genes. By using self organization map algorithm, they fell into four clusters, increased during the process, decreased during the process, transiently induced within 3 hour, and transiently repressed at 3 hour.
We identified the statistically significant enrichments of specific Gene Ontology terms in them. Gene expression-related genes were enriched in the induced clusters. Stress responsive genes were enriched in the induced, while photosynthesis genes were enriched in the repressed clusters. Some protein kinases, transcription factors, and chromatin-related factors were also regulated distinctively. Furthermore, promoter-reporter analysis for several up-regulated genes revealed their unique spatial expression patterns.
