7种桉树花粉微观形态及其亲缘关系分析

Analysis of Pollen Micro-morphology and Phylogenetic Relationship among Seven Species of Eucalyptus

摘要:

为了解我国常用桉树树种的亲缘关系，利用扫描电镜观察7种桉属（Eucalyptus）树种的花粉形态。结果表明，粗皮桉（E. pellita）、窿缘桉（E. exserta）的7个花粉性状大多处于前2位，其中粗皮桉花粉的赤道面长、宽和面积最大，分别为17.522、17.090 μm和300.830 μm²，而窿缘桉花粉的萌发沟长、宽和大小最大，分别为6.576、0.720 μm和4.718 μm²；赤桉（E. camaldulensis）花粉的赤道面最小，韦塔桉（E. wetarensis）花粉的萌发沟最小。聚类分析表明，在信息保留87.5%时，7树种可以分为3组，粗皮桉和窿缘桉聚在一组，韦塔桉和巨桉（E. grandis）聚在一组，其余聚在一组。粗皮桉、窿缘桉的花粉外壁纹饰较光滑，细叶桉（E. tereticornis）和赤桉属常规，尾叶桉（E. urophylla）、韦塔桉和巨桉较粗糙。从花粉形态分析，粗皮桉和窿缘桉的亲缘关系较近，韦塔桉、尾叶桉的亲缘关系较远，细叶桉、赤桉和巨桉的亲缘关系与传统分类结果一致。因此，7种桉树花粉形态反映了一些新的亲缘关系，对桉树的杂交育种有指导意义。

Abstract:

In order to understand the phylogenetic relationship of Eucalyptus species common in China, the pollen morphology of 7 species was observed under scanning electron microscopy. The result showed that the 7 pollen characters of E. pellita and E. exserta were mostly in the top 2. Among 7 species, the equatorial length (EL), width (EW) and area of E. pellita pollen were the largest with 17.522, 17.090 μm and 300.830 μm², respectively; the colpus length (CL), width (CW) and size of E. exserta pollen were the largest with 6.576, 0.720 μm and 4.718 μm², respectively; and the equatorial area of E. camaldulensis pollen was the smallest, colpus size of E. wetarensis pollen was the smallest. According to cluster analysis based on pollen characters, 7 Eucalyptus species could be divided into 3 groups under 87.5% of information remaining, including E. pellita and E. exserta, E. wetarensis and E. grandis, and the others. The pollen wall ornamentation of E. pellita and E. exserta were smooth, which E. tereticornis and E. camaldulensis was conventional, and that of E. urophylla, E. wetarensis and E. grandis was rough. From pollen morphology analysis, the phylogenetic relationship between E. pellita and E. exserta was closer, which between E. wetarensis and E. urophylla was farther, and that among E. tereticornis, E. camaldulensis and E. grandiswas consistent with traditional classification. Therefore, there were new interspecies relationships among Eucalyptus species from pollen morphology, which had guiding significance to the hybridization breeding of Eucalyptus.