Genetic diversity of Poncirus accessions as revealed by amplified fragment length polymorphism (AFLP)

Genetic diversity in 69 Poncirus accessions, including accessions from repositories in China, some newly-collected accessions, and several accessions from other countries, was investigated using AFLP markers. Fifteen primer combinations detected a total of 1,279 bands, among which 361 (28.2%) were polymorphic. All the accessions assayed could be discriminated using only three primer combinations, which could therefore be used as fingerprinting primers to identify each accession. Genetic similarity estimates, based oil the Jaccard similarity coefficient, ranged between 0.27 and 0.98, with an average of 0.77. Based on these results it was concluded that considerable levels of genetic variation exist in Poncirus accessions in China. A dendrogram, based on UPGMA cluster analysis, delineated the accessions into four major clusters. 'Fumin','Wangcang large leaf','Small leaf' and 'Dwarf' trifoliate orange accessions, which could not form a separate cluster by themselves, were clearly discernible from all other accessions. The dendrogram showed no clear association between the clustering of accessions and their geographical origin. Greater genetic diversity was observed in Hunan, Hubei and Henan Provinces than in other regions. A high level of genetic uniformity was observed among accessions from Shandong, Jiangsu, Anhui and Fujian Provinces. This study demonstrates the utility of AFLP markers in detecting polymorphism and estimating genetic diversity ill Poncirus. The results provide useful information for the collection, characterisation and utilisation of Poncirus germplasm.