Genetic characterization of Genista sericea Wulfen (Cytiseae - Fabaceae) as revealed by nuclear DNA content and ITS nrDNA region analysis

Genista sericea Wulfen, a northern Illyrian amphi-Adriatic species, presents a certain morphological variability. To clarify whether the genetic variations support the morphological differences among accessions of different geographic origin, analysis of nuclear DNA content and polymorphism of the internal transcribed spacer (ITS) dataset was studied. The variation in nuclear DNA content of G. sericea var. sericea and var. rigida is minimal (2.09 and 2.08 pg/nucleus respectively) and is correlated with equal chromosome numbers in both varieties. Intraspecific variability of the ITS region was studied on 13 accessions of G. sericea, 6 belonging to var. sericea and 7 to var. rigida. These accessions were analyzed in comparison to closely related species already studied. ITS sequences of G. sericea revealed large polymorphism and formed two main clusters. One cluster (6 accessions) comprehends var. sericea of northern Italy. Slovenia and northern Croatia; the other cluster (7 accessions) includes five accessions of var. rigida from southern Croatia and Montenegro and two from the Pollino massif (southern Italy). The later two accessions considerably differed from other accessions of var. rigida. This genetic analysis supports the previous assumptions, which subdivided G. sericea into at least two taxa. On the basis of the results presented, it is here suggested that the subdivision of G. sericea into var. sericea and var. rigida should be maintained.