Abstract: In order to identify the genetic relationship of pitaya germplasm materials, and screen excellent parents to improve breeding efficiency, ISSR molecular marker technology was used to study on the genetic background of 25 pitaya germplasm materials. After the data of 20 quantitative traits of plants and fruits standardizing, the genetic distance between varieties was calculated by Euclidean distance for comparative analysis. The results showed that 97 loci were detected by 7 ISSR primers, of which 93 were polymorphic, and the proportion of polymorphic bands was 95.88%. Based on UPGMA cluster analysis of molecular markers, 25 germplasm materials could be divided into 6 groups at the threshold of 0.54, and the similarity coefficients of various germplasm materials ranged from 0.41 to 0.86. The coefficient of variation of 20 quantitative traits ranged from 12.35% to 51.66%. Ward cluster analysis showed that 25 germplasm materials could be clustered into 6 groups at 5 Euclidean distances. The results of the two classification methods were not consistent, but both showed the rich genetic diversity of pitaya germplasm, and suitable parents could be selected according to the classification results and breeding purposes.

Key words: Hylocereus, germplasm resources, ISSR, quantitative traits, cluster analysis, genetic diversity

摘要： 为鉴定火龙果种质材料的亲缘关系，筛选优良亲本，提高育种效率，采用ISSR分子标记技术，对25份火龙果种质材料进行遗传背景研究，将植株及果实的20个数量性状数据标准化后，采用欧氏距离计算种质间遗传距离进行比较分析。结果显示，7条ISSR引物共检测到97个位点，其中多态性位点数为93个，多态性条带比例为95.88%。基于分子标记的UPGMA聚类分析，在阈值为0.54处可将25份种质材料分为6大组群，各种质材料的相似系数分布在0.41～0.86之间。20个数量性状的变异系数在12.35%～51.66%之间，Ward法聚类分析在欧式距离为5处，可将25份种质聚为6个组群。两种分类结果并不一致，但均显示出火龙果种质丰富的遗传多样性，可根据分类结果及育种目的筛选适宜亲本。

关键词: 火龙果, 种质资源, ISSR, 数量性状, 聚类分析, 遗传多样性