Abstract:

Betula platyphylla is a monoecious tree species with unisexual flowers. We have previously found a natural mutant of male inflorescence showing obvious features of male sterility,which has abnormal structure and reproductive development compared to wild type male inflorescence. To reveal the developmental mechanism of the male inflorescence mutant, a cDNA-AFLP molecular technique was used to investigate differentially expression profiles of candidate genes at early developmental stage of the male inflorescence. Totally 81 ESTs were obtained, among which 51 ESTs did not show homology to that in the GeneBank, and were considered as new genes. The other 30 ESTs showed high homology with known proteins. GO and KEGG functional annotation demonstrated that these putative proteins were involved in processes of catalytic activity, binding activity, signal transduction of biological regulation, biosynthesis and genes encoding transcription factors as well as flower development. Furthermore, 5 ESTs (MAP kinase, ubiquitin-conjugating enzyme, cellulose synthase, heat shock protein and cytochrome P450), related to the development of male inflorescence, were selected to detect the transcript expression profiles by using the quantitative Real-time RT-PCR technique in different tissues and developmental stages of the mutant male inflorescense. Results showed that the expression levels of these genes were differentially up- or down-regulated in the mutant male inflorescence, suggesting that most of these genes participated in the vegetative growth and reproductive development, and had closely relation to male flower growth retardation, anther and pollen abnormal development, which were the features of male sterility in B. platyphylla.

Key words: Betula platyphylla, mutant, cDNA-AFLP, male sterility, transcription expression