Construction Of SSH Library Of Betula Platyphyla Female And Male Inflorescence Based On SMART Strategy

Betula platyphylla is a kind of tree species with higher economic worth. Now the study about Betula platyphylla has maken delightful progress, but the study about the genes that control flower development during flowering time just start. In order to learn the background of gene expression in flower phase of Birch and obtain the EST related to flower development, the forwards and reverse SSH libraries of Betula platyphylla male and female inflorescence were constructed based on SMART strategy. Expressed sequence tags (EST) analysis was carried out to study the gene expression of flower development.In the SSH libraries, the rate of recombination was 72%, the average length of inserted fragments was 400bp, which was testified by PCR. Randomly selected clones were sequenced and 150 sequences were obtain in forward library which redundancy was 6.7%, 170 sequences in reverse library which redundancy was 36.7%.The BLASTX result of the ESTs showed that in the 140 unique transcripts of forward library, 121 ESTs were homologous to the genes identified previously, while other 9 ESTs matched unknown protein coding regions and 10 ESTs were novel sequences, in the 106 unique transcripts of reverse library, 84 ESTs were homologous to the genes identified previously, while other 20 ESTs matched unknown protein coding regions and 2 ESTs were novel sequences. Among 89 clones in forward library and 65 clones in reverse library, the ESTs with significant homology (E-value-10) with sequences in the public databases were mainly classified into 11 groups relating to Metablism, Cell rescue,defence. Cell structure. Cell growth, division. Energy, Photosynthesis, Protein destination. Protein synthesis. Signal transduction. Transcription and Transport facilitation. Among which the ESTs homologous to genes which control metablism and transcription were more.The SSH libraries contain some ESTs which were homologous to genes which control the flower development including flowering time, flower meristem identity, and flower organ identity, eg. MADS-box genes; Pollen-stigma interactions, eg. S-locus F-box genes; and pollen tube development and seed maturation, etal.. These ESTs provide materials for analysing the genes expression during flower time and cloning genes correlated Betula platyphylla flower development.Four ESTs which coding region are full were cloned and their BLAST result show they putatively code Cytochrome b5 isoform Cb5-B; ubiquitin/ribosomal protein CEP52; Low temperature and salt responsive protein and suspensor-specific protein respectively.