13种溲疏属植物的花粉形态与分类研究

Pollen morphological and taxonomic study on 13 Deutzia plants

关键词:  溲疏属, 花粉形态, 扫描电镜, 聚类分析, 亲缘关系

Key words:  Deutzia, pollen morphology, scanning electron microscope, cluster analysis, phylogenetic relationship

摘要:

为深入研究溲疏属植物花粉形态的分类学意义,厘清溲疏属种间和品种间的亲缘关系,该研究利用扫描电镜观察6种1变种和6品种(以下简称13种)溲疏属植物的花粉形态特征(包括花粉大小形状、外壁纹饰及萌发沟),并对花粉定量特征进行主成分分析和聚类分析。结果表明:(1)溲疏属植物花粉保守性较高,所测13种溲疏属植物花粉均为单粒长球形或超长球形,中型和小型花粉分别占23.08%和76.92%,极面观为三沟圆形,赤道面观为长椭圆形或椭圆形,外壁纹饰为粗疏网状纹饰。种间和品种间花粉大小、极轴长、赤道轴长、萌发沟长、网眼特征差异显著,小花溲疏是唯一网眼呈不规则形、具棱形突起的溲疏种。6个品种花粉出现不同程度皱缩、畸形状态,推测与花粉发育不全或败育有关。(2)提取花粉大小、网脊宽度和萌发沟宽3个主成分因子,当欧氏平均距离阈值为15时,13种溲疏属植物被划分为4个类型,6种1变种中异色溲疏、宁波溲疏、小花溲疏和大花溲疏亲缘关系较近,旱生溲疏与其原变种大萼溲疏亲缘关系较近,粗齿溲疏与上述6种亲缘关系较远,6个品种中‘日光'‘陀飞轮宝石'和‘草莓田'亲缘关系较近,‘雪绒花'‘雪樱花'和‘钟花'亲缘关系较近,聚类分析结果支持中间溲疏组与溲疏组分开的观点。(3)推测溲疏属为绣球花科下较晚分化类群。该研究中除宁波溲疏和异色溲疏外,其余4种1变种和6品种花粉形态特征均为首次报道,该研究结果表明花粉形态特征为溲疏属分类及亲缘关系分析提供了重要佐证。

Abstract:

This study aimed to investigate taxonomic significance of pollen morphology and clarify phylogenetic relationship of Deutzia. The pollen morphological characteristics including pollen shape and size, exine ornamentation and colpus of six species, one variety and six cultivars in Deutzia(following abbreviated as 13 Deutzia plants)were observed by scanning electron microscope(SEM), and principal component analysis(PCA)and cluster analysis were conducted on the quantitive characteristric of pollen. The results were as follows:(1)The pollen of 13 Deutzia plants was highly conserved. The observed pollen of 13 Deutzia plants were prolate or perprolate, with medium-sized and small pollen accounting for 23.08% and 76.92%, respectively. The polar view of the pollen was tricoplate with a circular amb, and equatorial view was oblong or oval. The pollen exine ornamentation of 13 Deutzia plants was all rough reticulate type. The pollen size such as polar and equatorial axis length, colpus length and lumina characteristics varied significantly among species and cultivars. D. parviflora was the only species with irregularly lumina and protuberant mesh. A large number of wrinkles and irregular deformities were observed in 6 cultivars, which could be due to incomplete development of pollen.(2)Three principal component factors were selected by PCA, including pollen size, mesh ridge width and ditch width. When the Euclidean mean distance was 15, 13 Deutzia plants could be divided into four types. Among six species and one variety, D. discolor, D. ningpoensis, D. parviflora and D. grandiflora were closely related; D. calycosa var. calycosa and D. calycosa var. xerophyta were closely related. In contrast, D. crassidentata was distantly related to the first six species. Among six cultivars, D. gracilis ‘Nikko', Deutzia × magnifica ‘Toubillon' and Deutzia × hybrida ‘Strawberry Fields' were closely related. Deutzia × rosea ‘Yuki Snowflake', Deutzia × rosea ‘Yuki Cherry Blossom' and Deutzia × rosea ‘Campanulata' were closely related. Cluster analysis results support the view that sect. Mesodeutzia and sect. Deutzia should be separated.(3)Deutzia was presumed to be a relatively late-diverging group in Hydrangeaceae. This is the first report of pollen characteristics of four species, one variety and six cultivars except for D. ningpoensis and D. discolor, and the results of this study provide important evidence to the classification and phylogenetic relationship analysis of Deutzia.