苹果地方品种花粉形态分类及聚类研究

Study on the Pollen Morphology,Taxonomy and Clustering of the Local varieties of Apples

利用扫描电镜观察了苹果属植物25个地方品种、10个野生种类型、3个栽培品种、2个杂交种共40个不同类型的花粉形态特征,根据花粉形状、极轴和赤道轴长度等11个指标,采用类平均法(UPGMA)对欧式距离进行聚类分析。结果发现:所观察花粉类型均为N_3P_4C_5类型,呈两侧对称的长球形或超长球形,花粉表面有条状饰纹和穿孔,各类型间花粉粒大小及外壁纹饰差异明显,地方品种早白海棠外壁饰纹无条纹束,区别于其他资源。聚类分析表明:在遗传距离1.30水平上,40份资源聚为9大类,地方品种与野生资源、栽培品种相互交错,部分地方品种单独聚为一类。地方品种花粉形态多样性极为丰富,除一些特异类型,花粉形态不能单独作为地方品种分类的依据,需结合其他分类方法;部分地方品种起源于新疆野苹果或者新疆野苹果与其他野生资源或者栽培种的自然杂交,部分地方品种经过相互杂交和人工选择形成其类型的多样性,具有重要的科研价值。

Pollen morphology of 25 local varieties,10 wild species,3 cultivars and 2 hybrids of Malus were observed through scanning electron microscope,cluster analysis with UPGMA based on the shape,the length of equatorial axis,the length of polar axis and the other 8 indexes. The results indicated that Malus pollen belonged to the N3P4C5 type,prolate sphericity or ultra prolate sphericity with striate pattern and some small pores on the exine surface,the size and exine sculpture of pollen from different varieties were significantly distinct,the local variety‘Zaobaihaitang＇which didn＇t have stripe was different from others. From the UPGMA cluster analysis at the 1. 30 level of genetic distance,40 taxa could be classified into 9 groups,some local varieties distributed over the wild species,cultivates and hybrids,the others clustered into a category respectively. Pollen morphology of local varieties were rich in diversity,it need to be combined with other classification methods to taxonomy the local varieties except for some specific local varieties; and some local varieties originated from M. sieversii（ Ledeb.） Roem or originated from the natural hybridization between M. sieversii（ Ledeb.） Roem and others wild species or cultivars,other local varieties and the diversity emerged after natural hybrid and artificial selection,and the local varieties have important value in scientific research.