Development-specific genes and their expression at the RNA level.

A total of seven clones, which are specific for the development of carrot somatic embryo cells, were constructed and screened from the cDNA expression library of phage lambda gt11. The purification of plaques, isolation of DNA from the phages, digestion of the clone's DNA with EcoRI restriction enzyme, identification of the inserts on the agarose gel by electrophoresis and subcloning of cDNA inserts from phage lambda gt11 vector into plasmid pIBI or pUC18 were performed respectively. The data of cross hybridization by Southern blot analysis indicated that clones 16,22,50 and 60 are new cDNA genes. In addition, the new cDNA genes tissue-specific expression on variety organs in the carrot plant, such as flower, petiole, leaf and root, as well as time-course expression in callus and embryo cells of different culture periods were determined through Northern blot analysis. The results suggested that the corresponding gene for clone 22 is a specific gene which is regulated by development and closely associated with carrot somatic embryogenesis.