花粉形态数量化分析在中国梨属植物起源、演化和分类中的应用

根据植物花粉性状的稳定性和遗传保守性,在对中国梨属植物13个种的花粉形态观察研究的基础上,采用数量化的分析方法,对花粉形态7个性状进行了聚类分析。结果表明:不同种间的相似距离系数存在一定差异,种间相似距离系数在0.2215～5.0675之间变化,最大值与最小值相差23倍。褐梨与河北梨、麻梨与川梨、白梨与沙梨这3对种间的相似距离均小于与其它种间的相似距离。根据聚类结果,把相似距离系数等于0.3作为划分类群的标准,供试的13个种可划分为4个种群。在相似距离系数≤0.3的种群中有豆梨、杜梨、麻梨、川梨、褐梨和河北梨;相似距离系数>0.3≤0.6的有秋子梨、新疆梨和西洋梨;相似距离系数>0.6≤0.9的有木梨、沙梨和白梨;相似距离系数>0.9的只有杏叶梨。从花粉形态遗传相似距离聚类分析中还发现,豆梨与河北梨、褐梨、川梨、杜梨、麻梨、秋子梨、西洋梨、木梨、新疆梨、沙梨、杏叶梨、白梨的遗传距离依次为0.2832、0.4587、0.5842、0.6694、0.7645、1.1027、1.1648、1.3238、1.3280、2.2536、2.5400、2.8350。若把豆梨看作是最原始的种,那么,从豆梨到白梨它们的遗传相似距离越来越大,显示出它们的亲缘关系越来越远,白梨是最进化的种类。

Application of Numerical Taxonomy of Pollen Morphology on Origina tion, Evolution and Classification of Pyrus L. In China

Pyrus spp.existed in China and7morphological characters of their pollen were used as material and clustered by the way of numerical taxonomy.Results showed there were certain differences in the distance coefficients of them,which varied from0.2215to5.0675,and the maximum was twenty three times more than the minimum.The similarity distance of three pairs of species,namely between P.phaeocarpa Rehd.and P.hopeihensis Yü,P.serrulata Rehd.and P.pashia Buch.-Ham.,P.breschneideri Rehd.and P.pyrifolia Nakai,was smaller than the distance of any other pairs.Based on the clustering analysis the13species could be classified into4groups.If the distance coefficient of similarity(DCS)of0.3is used as the classification standard,the DCS of P.calleryana Dcne.,P.betulaefolia Bge.,P.serrulata Rehd.,P.pashia Buch-Ham.,P.phaeocarpa Rehd.and P.hopeihensis Yüare or below0.3;the DCS of P.ussriensis Maxim.,P.sinkiangensis Yüand P.communis L.are more than0.3but lower than0.6;the DCS of P.xerophilas Yü,P.pyrifolia Nakai and P.ussuriensis Maxim.are more than0.6but lower than0.9.Only the DCS of P.armeniacafolia Yüis more than0.9.The conservation of pollen characters reflects the relationship among the species to certain extent.The genetic distance between P.callgana Dcne.,P.hopeihensis Yü,P.phaeocarpa Rehd.,P.pashia Buch.-Ham.,P.betulaefolia Bge.,P.serrulata Rehd.,P.ussurensis Maxim.,P.communis L.,P.xerophila Yü,P.sinkiangensis Yü,P.pyrifolia Nakai,P.armeniacafolia Yüand P.bretschneideri Rehd.are0.2832,0.4587,0.5842,0.6694,0.7645,1.1648,1.3238,1.3280,2.2536,2.5400,2.8350respectively.According to the clustering analysis of their genetic similarity distance of pollen morphology,if P.callergana Dcne.was regarded as the most original species,the genetic similarity distance has been getting longer and longer from P.callergana Dcne.to P.bretschneideri Rehd.showing the more and more distant relationship between them;from all the above mentioned,it is believed that P.bretschneideri Rehd.would be probably the most evolutive species.