黄杨是栽植很广的庭园观赏灌木,美国长木植物园从世界各地收集了许多优良品种.仅从形态上来区别这些黄杨品种是很困难的.为鉴定20个黄杨优良品种,我们分别从形态特征(叶、习性和长势)和分子标记(AFLP标记)两方面着手,综合分析它们的亲缘关系.三个AFLP引物结合在75和500 bp DNA片段间一共产生212个条带.每一个黄杨品种平均有74个条带,最低者有50条,最高者有108条;通常可用于签定的特有条带在0到15条之间.品种间的遗传距离介于0.028和0.439之间.用PAUP软件,我们得到一个LIPGMA树状图,并将每一步有显著差异的标在图上.从分子特性来讲,这20个黄杨优良品种可能起源于4到5个种,并可很清楚地分为12个栽培变种.形态特征也支持分子特性的结论.由此可见,结合形态特征和分子标记是确定遗传关系、鉴定栽培变种和分子辅助定性育种的一个很好的方法.%Boxwoods(Buxus L.)are among the most widely cultivated ornamental shrubs.Longwood Gardens displays and trials many boxwood taxa from around the world.Cultivar identification and species delineation in boxwoods is problematic when based solely on morphological characteristics.To verify identity of 20 boxwood accessions from the trial beds of Longwood Gardens,their morphological features(leaf characters,growth habit,and landscape appearance)were recorded.These data were validated later with the analysis of AFLP markers.The AFLP markers were generated separately without any knowledge of the morphological characteristics.From the three-primer-pair combinations,a total of 212 useful markers between 75 and 500 bps fragment sizes were obtained.The average number of markers for each accession was 74 and the total markers for each accession varied from 50 to 108.The unique bands,which can be the potential diagnosis markers,were among zero to 15.Genetic distances ranged from 0.028 to 0.439.Only one UPGMA tree was generated using PAUP and the number of characters that changed unambiguously on each branch was recorded.From molecular data,the 20 accessions might derive from four or five different species and could be distinguishably classified into 12 different cultivars.The morphological data fully supported the results from molecular data.The combination of both morphological and molecular data is a powerful tool for determining genetic relations,cultivar discrimination,and targeted breeding.
展开▼
