色季拉山10种报春花属植物花粉形态及其分类学意义

Pollen morphology and its taxonomic significance of 10 Primula species from the Shergyla Mountains

关键词:  报春花属, 西藏, 花粉形态, 聚类分析, 孢粉学

Key words:  Primula, Tibet, pollen morphology, clustering analysis, palynology

摘要:

采用扫描电镜法,观察和比较了西藏色季拉山 10 种报春花的花粉形态特征,同时进行聚类分析,以期为该属植物分类提供孢粉学证据,并进一步为西藏报春花属植物杂交育种及种质资源的利用提供参考。结果表明:(1)供试 10 种报春花属植物的花粉形状为扁球形、近球形,其中,工布报春(Primula kongboensis)的花粉粒最小,暗紫脆蒴报春(P. calderiana)的花粉粒最大,西藏报春(P. tibetica)为多沟型花粉,其余报春花的花粉一般具 3 孔沟,大部分孔沟在极区汇合形成复合沟。(2)花粉外壁纹饰大多为穴状或网状,其中,中甸灯台报春(P. chungensis)和西藏报春为网状纹饰中的粗网状类型。(3)虽然基于花粉形态的聚类分析与植物学分类表现出一定的一致性,但粉报春组的西藏报春和工布报春则由于在孢粉学特征上具有明显差异,因此保持了相对较远的亲缘关系。该研究初步认为,色季拉山 10 种报春花粉形态存在种间差异,研究结果可为植物分类提供一定的参考依据。然而,在进行分类时,仍然需要结合形态学特征、分子生物学等方面综合考虑。

Abstract:

Primula is an important genus of Primulaceae, which has high ornamental value because of diverse flower colors and long flowering period. In order to provide palynology basis for the taxonomy of this genus, we observed and compared the pollen morphological characteristics of 10 Primula species from the Shergyla Mountains in Tibet by scanning electron microscopy(SEM). Moreover, clustering analysis was carried out on the basis of these characteristics of pollen morphology. The results were as follows:(1)Pollen shapes of 10 Primula species varied from oblate to nearly spherical. Among these species, the pollen of P. calderiana was the biggest, and the smallest was that of P. kongboensis. The germinal aperture of P. tibetica was stephanocolpate type. The other pollens usually were tricolporate type, most of the colpus converged to form parasynocolpus in the polar region.(2)The pollen exine ornamentation were mostly foveolate or reticulate, which of P. chungensis and P. tibetica were coarsely reticulate.(3)In traditional classification, 10 species belong to 7 sections respectively. Clustering analysis based on pollen characteristics showed a certain level of consistency with the traditional classification. However, P. tibetica and P. kongboensis, both belonging to Sect. Aleuritia, maintained a relatively distant relationship due to their obvious differences in pollen traits. The preliminary results show that there are interspecific differences in the pollen morphology of 10 Primula species, which can provide a certain degree of reference for classification of plants. But it should be reminded that in addition to pollen characteristics, morphology and molecular biology still need to be comprehensively considered in classification.