Morphological Characterization and SSR Profiling of Local Citrus Germplasm from Southern Croatia

Abstract

Local citrus germplasm is a valuable resource for biodiversity conservation and the preservation of traditionally maintained plant material. This study characterized 16 deliberately selected citrus accessions from private gardens in southern Croatia, each represented by a single tree, using 99 IPGRI descriptors and a panel of 15 SSR markers. The objectives were to identify the variables with the highest relative discriminating power, evaluate phenotypic relationships among the selected accessions, and determine their molecular correspondence with well-characterized reference cultivars. Phenotypic analyses identified 20 variables with the highest relative discriminating power. Hierarchical clustering and discriminant analysis of principal components (DAPC) revealed phenotypic structuring that broadly reflected the initial field-based horticultural group assignments. Multilocus SSR analysis identified five distinct 15-locus SSR profiles among the 16 Croatian accessions. The Croatian sweet orange, lemon, and sour orange accessions shared their respective 15-locus SSR profiles with the corresponding analyzed reference cultivars. Among the accessions initially assigned to the mandarin group, two distinct multilocus SSR profiles were identified: one was shared with the analyzed Citrus clementina reference cultivars, whereas the other was shared with the analyzed Citrus deliciosa reference cultivars. The observed variation should not be interpreted as an estimate of overall citrus diversity in southern Croatia because the accessions were selected in part for their morphological and pomological distinctiveness. The combined use of phenotypic and molecular characterization provides a basis for documentation, conservation, and further evaluation of local citrus germplasm.