Abstract: To investigate the differentially expressed genes during the development of Betula platyphylla female inflorescence, a suppression subtractive hybridization (SSH) library was constructed by using the cDNAs from the female and male inflorescences, respectively, as the tester and the driver. The recombination of the SSH library was 72%, with about 400 bp of average insert length. The clones from SSH library were selected randomly for sequencing. Totally, 150 ESTs were obtained, with the GenBank accession number EE284580-EE284681, EE595316-EE595363. The ESTs were functional annotated by BlastX. Among them, 111 ESTs significantly matched with Nr database, and were further classified into functional groups including metablism, cell rescue, defence, transcription, energy and signal transduction, etc.. The genes related in flower development were found in our EST collection, which account for 21% of known function ESTs. These genes including MADS-box, S-locus F-box, etc., and their function involved in inflorescence forming and differentiation regulation, pollen-stigma interactions control and pollen tube development, etc. The obtaining of these EST will provide a reference for analysis of gene expression in the inflorescence of B.platyphylla, and also will make a base for cloning genes related with developments of follower and gene functional analysis in follower development.

Key words: Betula platyphylla Suk, development, expressed sequence tag, female flower, suppression subtractive hybridization library