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.%白桦是雌雄同株的单性花树种,已发现的天然的雄花序突变体,其结构和生殖发育均不同于正常雄花序,显示出明显的雄性不育特征.为揭示该雄花突变体的发育机制,采用cDNA-AFLP分子标记技术,分析白桦雄花突变体发育早期的差异基因表达谱,共获得81个ESTs,51个ESTs与GenBank中的基因相似性较低,视为新基因,30个ESTs与已知蛋白具有较高同源性.GO和KEGG对其功能的注释表明,这些蛋白参与催化活性、结合活性、生物调节信号转导、生物合成以及基因编码转录因子和花发育等过程.选择5个与白桦花发育有关的ESTs,分别为MAP激酶、泛素结合酶、纤维素合成酶、热激蛋白和细胞色素P450,应用Real-time RT-PCR检测它们在白桦雄花突变植株的不同组织和雄花发育过程的转录表达,结果表明,这些基因在白桦突变植株中表达水平发生不同程度的上调或下调表达,推测它们参与白桦营养生长和生殖发育,并与雄花的迟缓发育、花药和花粉发育异常等雄性不育特征有关.
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