14种酢浆草属植物花粉形态及其亲缘关系分析

mail)[e-mail]。Pollen morphology and phylogenetic relationship of 14 Oxalis species

关键词:  酢浆草属, 花粉形态, 异型花柱, 异常花粉, 亲缘关系

Key words:  Oxalis, pollen morphology, heterostyly, aberrant pollen, phylogenetic relationship

摘要:

利用扫描电镜对14种酢浆草属植物花粉形态及表面纹饰进行观测,对其花粉形态进行聚类分析,并基于孢粉学聚类结果,探讨其种间亲缘关系。结果表明:(1)所观测的14种植物花粉粒为近球形或扁球形,极面观均为三裂圆形,多数为3沟花粉粒,稀2沟(星星酢浆草)和4沟(黄花酢浆草); 其中,96.3%花粉粒为中等大小,3.7%为小花粉粒; 不同花柱类型都表现为长雄蕊花粉比短雄蕊花粉大; 外壁纹饰可分为复网状和网状两类。(2)首次发现3种存在异常花粉粒,分别为桃之辉酢浆草、一片心酢浆草及黄花酢浆草,花粉的异常表现为萌发沟数目和排列异常,其外壁纹饰结构与正常花粉粒未有明显不同。(3)根据外壁纹饰可将14种划分为2大类。一类为复网状花粉,仅构巢酢浆草和果香酢浆草为该类纹饰,二者亲缘关系较近。另一类为网状花粉,对12种具网状花粉酢浆草进行聚类分析可划分为4个类型,其中桃之辉酢浆草、双色冰淇淋酢浆草、藤双色冰淇淋酢浆草亲缘关系较近; 扁平酢浆草、黄花酢浆草、纳马夸纳酢浆草及兔耳酢浆草亲缘关系较近; 大花酢浆草、星星酢浆草、乳白蝴蝶叶酢浆草亲缘关系较近; 吉氏酢浆草和一片心酢浆草与其他酢浆草亲缘关系较远。该研究结果表明,花粉形态相近的物种在植株形态上有一定的相似性,花粉形态特征可作为种间亲缘关系研究和分类划分依据,进一步为酢浆草属植物杂交育种亲本选择提供理论基础。

Abstract:

Most Oxalis are highly ornamentally valuable, but their taxonomy is difficult, which greatly limits the landscape application of this genus. The pollen morphology and exine ornamentation of 14 species of the Oxalis were observed using scanning electron microscopy, and their pollen morphology was clustered and analyzed to explore their interspecific relationship based on the results of palynological clustering. The results were as follows:(1)The pollens of the 14 species observed were subspheroidal or oblatesphere, and in polar view they were all 3-colpate, of which 96.3% were medium-sized and 3.7% were small, with different style types showing the largest grains were produced in stamens with long filaments and the smallest ones in stamens with short filaments; most pollen grains were 3-colpate, sparsely 2-colpate and 4-colpate, O. stellata and O. pes-caprae, respectively; exine ornamentation could be divided into two categories: supra-areolate and reticulate.(2)For the first time, three species with aberrant pollen grains were observed, namely O. glabra, O. simplex and O. pes-caprae. The aberrant pollens exhibited as abnormal number and arrangement of the colpi, but normal exine structure. There were 2-zonocolpate grains in O. glabra, spiralaperturate grains in O. simplex, and 4-zonocolpate grains and spiralaperturate grains in O. pes-caprae. (3)The 14 species could be divided into two categories according to the exine ornamentation, one included O. massonorum and O. nidulans with supra-areolate pollen. The other category included 12 species with reticulate pollen. Species in the latter category could be further divided into four types: O. glabra, O. versicolor, and O. tenuifolia were more closely related; O. compressa, O. pes-caprae, O. namaquana, and O. fabaefolia were more closely related; O. bowiei, O. stellata, and O. perdicaria were more closely related; O. zeekoevleyensis and O. simplex were relatively distantly related to other Oxalis. The results of this study show that species with similar pollen morphology have certain similarity in plant morphology, and the pollen morphology characteristics can be used as the basis for the study of phylogenetic relationship and taxonomic classification, which can further provide a theoretical basis for the selection of parents in Oxalis cross-breeding.