Genetic Diversity Analysis of Guangxi Kumquat (Fortunella Swing) Germplasm Using SRAP Markers

In order to understand the genetic diversity of germplasm resources of kumquats in Guangxi, 14 kumquat germplasm resources in Guangxi and 12 accessions from other provinces were analyzed by using SRAP markers. In total, 19 primer pairs with high stability, good reproducibility, and high polymorphism were chosen for analysis of all 26 kumquat genotypes. Among the 104 amplified bands, 90 (86.54%) were polymorphic. SRAP markers were analyzed by employing Principal Coordinate Analysis, Population Structure Analysis, and Hierarchical Cluster Analysis (UPGMA). The classification results showed that the 26 kumquat germplasm resources could be divided into 5 groups, including cultivated kumquat, intergeneric hybrid, wild kumquat from other provinces, wild kumquat, and hybrid kumquat from Guangxi. The Guangxi kumquat germplasm had high genetic diversity, and were clearly divided into three groups: cultivated kumquat, wild kumquat, and hybrid kumquat. Additionally, the eight cultivated kumquat varieties in Guangxi were further divided into two subgroups. Wild kumquat in Guangxi or in other provinces belonged to different groups; meanwhile, the Guangxi kumquat hybrid formed an independent group, thus indicating that Guangxi wild kumquat and hybrid kumquat possess certain specificity, or they possibly belong to different species. Among the tested 26 kumquat accessions, 23 unique genotype-specific SRAP markers were detected for 14 kumquat genotypes, which were positively identified. For the remaining 12 accessions without genotype-specific markers, they were distinguished by various combinations of markers. These results may have certain importance for kumquat genetic research and cultivar selection.