文心兰类原球茎形态建成及电子传递蛋白和凯氏带蛋白基因的极性表达模式分析

Protocorm-like Body Morphogenesis and Bipolar Expression Patterns Analysis of Electron Transfer Vectors and Casparian Strip Related Proteins Genes in Oncidium hybridum

以文心兰‘柠檬绿’(Oncidium hybridum‘Honey Angel’)为材料进行类原球茎发育过程的形态和结构观察,对其离体形态建成进行分析,并对类原球茎(protocorm-like body,PLB)分化过程中的顶部和基部组织以及组培苗的根、茎、叶中的凯氏带蛋白基因CASP和电子传递蛋白基因Fd(ferredoxin)、FNR(ferredoxin-NADP+oxidoreductase)的表达模式进行分析。结果显示:类原球茎在分化过程中逐步建立了两极性。随着类原球茎的发育,自顶端向基部形成维管形成层,继而形成维管束;之后有叶原基产生并形成单子叶式茎尖结构和出现类原球茎胚轴的伸长,无胚根形成。类原球茎形成幼苗后植株基部有侧根的产生。实时荧光定量PCR结果表明:在根中高表达和在茎中高表达的CASP、FNR和Fd基因在类原球茎不同发育阶段和组织中存在极性的差异表达,参与了无胚根体细胞胚胎的生长发育过程。综上所述,文心兰体细胞胚在发育过程中从弱分化器官向茎叶器官转变,形成兰花特有的非同步体细胞胚胎发育现象——类原球茎。

The morphology and structure of the protocorm-like body(PLB)of Oncidium hybridum‘Honey Angel’during development were observed and the PLB in vitro morphogenesis was analyzed.The expression patterns of CASP(Casparian strip membrane domain protein)and electron transfer genes Fd(ferredoxin)and FNR(ferredoxin-NADP+oxidoreductase)in PLBs,roots,stems,and leaves of in vitro cultured seedlings and PLB apical and basal tissues during the PLB differentiation were further analyzed.The results showed that the PLBs gradually established polarity during the differentiation in which a vascular bundle was formed from the PLB sub-apical area to the basal part.Later,a leaf primordium was generated and the monocotyledon shoot apical structure was formed. Root formation was in a lateral patternand occurred after the PLB embryonic axis had significantly elongated. The basal tissue of the PLB did not develop any embryonicroot. Lateral roots occurred in the seedling stage. It is concluded that the PLB development of O. hybridum is a typeof asynchronous somatic embryogenesis, i,e, the embryonic root does not form during embryogenesis. Results of real-timequantitative PCR showed CASP, FNR and Fd genes showed differentially bipolar expressions in different developmentalstages and tissues of PLBs, playing roles in the rootless PLBs morphogenesis. In summary, the somatic embryos of O. hybridumtransform from weakly differentiated organs to shoot-like organs during development, forming an orchid-specific somaticembryogenic phenomenon, PLB.