Abstract:
The outermost layer epidermis of a plant stem plays an important role in protection and environment-sensing. The mechanisms of sensing and response to the environment through the stem epidermis remain unclear. Here we report enriched expression of genes involved in stress resistance and signal transduction functions in the stem epidermis of both D. purpureus and A. thaliana by cDNA cloning and QPCR in D. purpureus and by analysis using dataset from a genome-wide comparison with cDNAs differentially expressed between the epidermis and inner parts of top and base stem in A. thaliana. Among 188 cDNAs from the stem epidermis of D. purpureus, 13% and 17% were related to signal transduction and defense respectively. Most of them were up-regulated more in the stem epidermis than the inner stem, as well as in A. thaliana. Also, the distribution of the numbers and specificities of up-regulated genes related to signal transduction and regulatory networks in the epidermis and inner stem revealed the possibility of positional differences in regulation. The results revealed the importance of the epidermis in signal transduction and plant defence.
