Klasea is a taxonomically complex genus in which there are many problems, mostly with Klasea kotschyi and K. hakkiarica. It is challenging to differentiate the genera based on morphological characters alone. Revision studies performed on the basis of molecular data obtained from studies conducted in recent years have made the phylogenetic relationships and systematic positions of the taxa more apparent and reliable. In this study, Klasea, Serratula, Jurinea and Centaurea species native to Turkey, were collected from different localities of Anatolia and DNA was isolated from the collected samples. The data were analyzed ordination analyses including UPGMA and PCA using NTSYSpc 2.1. The infrageneric and intergeneric phylogenetic relationships between Klasea and other related genera were also characterized. The Klasea species were grouped into three clusters. It was determined that taxa Klasea kotschyi and K. hakkiarica are separate but closely related. Moreover, it was observed that the Klasea lasiocephala a separate group within the genera. Clearly the genera Klasea, Serratula, Jurinea and Centaurea are phylogenetically differentiated on the dendogram.

Asteraceae , ISSR, Klasea , Serratula , Molecular systematics, Phylogeny

The tribe Cardueae (Asteraceae) is generally accepted to be classified into five subtribes named Echinopinae, Carlininae, Carduinae, Centaureinae and Cardopatiinae (Susanna et al. 2006). Cardueae include perennial, biennial, or monocarpic herbs and shrubs and, less often, annual herbs or small trees (Barres et al. 2013). However, delineation of these taxonomic entities is highly problematic. Beyond the limits of the tribes, the boundaries between these units are also very difficult to establish. Also, some large genera of the tribes have generic delimitation problems: Carduus L. (90 species), Cirsium Mill. (250 species), Centaurea L. (400 species), Cousinia Cass. (800 species), Serratula L. (70 species), and Saussurea DC. (more than 300 species) (Garcia-Jacas et al. 2002). Extensive work conducted recently by Garcia-Jacas et al. (2000, 2001) and Font et al. (2002) have clarified the delineation of Centaurea. Limited studies also exist on Cirsium and Carduus (Haffner and Hellwig 1999), but most of the taxonomic problems persist. The genus Klasea Cass. constitutes a taxonomically complex group of plants with generic boundaries are unclear, especially at the generic level surrounding genus Serratula (Martins and Hellwig 2005). Klasea Cass., traditionally treated as a section within Serratula L., is widely accepted at the generic level (Martins 2006). Klasea is naturally distributed in Central Asia, Iran, Turkey, China, Himalayas, south east Europe and south Russia. Klasea is located within the monophyletic tribe Cardueae, in the subtribe Centaureinae (Susanna et al. 2006).

16 species were reported for the genus Serratula in Turkey (Davis and Kupicha 1975; Davis et al. 1988). Then all Turkish Serratula species were transferred to Klasea except Serratula tinctoria (Greuter 2003; Martins 2006). Thus, Klasea is represented by 15 species and Serratula is represented by one species within the Mediterranean and Irano-Turanian phytogeographic regions of Turkey (Dogan et al. 2012). Five of these species are endemic to Turkey, resulting in an endemism ratio of 33.3% (Dogan et al. 2012).

Currently, morphological revisions of various plant taxa are often supported by molecular data (APG 2003). As compared with morphological data, DNA sequences are not influenced by the environmental conditions in which the plants have grown; hence they serve as a powerful tool in resolving taxonomical and systematical problems. When compared with the phenotypic characters, by using different molecular marker systems, more reliable results were also obtained by a number of researchers that used different plant groups (Yang et al. 1996; Joel et al. 1998; Soranzo et al. 1999; Bremer et al. 2001; Mengitsu et al. 2002; Ash et al. 2003; Jump et al. 2003; Pharmawati et al. 2004; Dogan et al. 2007; Ali et al. 2013).

The RAPD (Randomly Amplified Polymorphic DNA) fingerprinting method is widely used and has a wide range of applications (Williams et al. 1990). However, because RAPD is a highly sensitive method, it should be used with great care. The ISSR (Inter Simple Sequence Repeat) has much higher levels of reproducibility than RAPD, for which reason it is preferable (Zietkiewicz et al. 1994, Prevost and Wilkinson 1999; Dogan et al. 2007; Hakki et al. 2010). The ISSR method is very widely used for the analysis of genetic diversity (Prevost and Wilkinson 1999).

Simple sequence repeats (SSRs), also known as microsatellites, are tandemly repeated di-, tri, tetra- or penta-nuclotide sequences (mainly within the range of 10–80 repeats of the core unit) that are abundant within eukaryotic genomes. A high level of genomic variation is generated by the more or less evenly distributed microsatellite sequences present within the plant and animal genomes. The high levels of genomic variation are widely used for genetic variation analysis of both wild plants (Wolfe et al. 1998; Dogan et al. 2010; Laosatit et al. 2013; Khalik et al. 2014) and crop plants (Vosman and Arens 1997; Hakki et al. 2001; Mohammadzadeh et al. 2011). Microsatellites can be used in inter- as well as intra-species analyses (Soranzo et al. 1999). However, the technique requires prior sequence information for the locus-specific primers, a feature that renders it difficult to be applied to plants for which no adequate genomic sequencing studies exist. Without considering their difficulty or cost (Hakki and Akkaya 2000), numerous microsatellite loci have been identified for economically important crops such as wheat, rice or maize. In Klasea, however, they have not been utilized.

In this study, Klasea species, which are difficult to delineate using morphological traits, were collected from their natural habitats in Turkey. DNA was isolated and fingerprinting was performed using a highly reliable and reproducible technique that mimics the application ease of RAPDs. The method employed to assess the genetic diversity and to resolve the genetic relationships among the species is a technique derived from SSR characterization based on PCR amplification of ISSR regions primed by a single oligonucleotide corresponding to the targeted repeat motif. The SSR-containing primers are usually 16-25 base pair long oligonucleotides anchored at the 3’- or 5’-end by two to four arbitrary, and often degenerate, nucleotides (Fang et al. 1997). The primer can be based on any of the motifs found at SSR loci. In these conditions, only sequence regions flanked by the two adjacent identical and inversely oriented microsatellites are amplified. Overall, the technique does not require prior sequence information (an advantage against microsatellites) and its reliability is higher than RAPD’s.

The aim of this study was to determine the genetic relationships among selected Anatolian-originated Klasea, Serratula, Jurinea and Centaurea species collected from diverse regions of Turkey and to use a DNA-based molecular marker system to resolve the unclear and controversial status of these species based on conventional morphological characters.

Silica gel dried plants collected from 19 different natural habitats were taken to the laboratory. The total number of species collected and used in the phylogenetic analysis was 19. DNA extractions were first attempted using a standard 2X CTAB method. Due to the poor DNA quality produced by the CTAB procedure, a commercial kit (Nucleon phytopure) was used in all isolations and repeated extractions were conducted whenever necessary.

From an initial screening of 20 ISSR primers, seven primers revealed high levels of polymorphisms. These primers generated 85 highly polymorphic fragments that were consistently amplified in repeated experiments conducted on separate dates. The GC percentages of the selected primers were within the range of 38.8–66.7%. The characteristics as well as the sequences of the primers revealing a polymorphism are shown in Table 2. The primer ISSR F3 amplified the highest number of polymorphic fragments (14 bands) and primer ISSR F5 yielded the lowest number of fragments (10 bands). In total, the average number of polymorphic fragments per primer used was roughly 12. A representative figure containing ISSR F3 and ISSR F5 banding patterns is given in Figure 1.

Figure 1. 

Representative agarose gels where PCR products were amplified with the primers ISSR F5 (highest number of polymorphic bands, top) and ISSR F5 (lowest level of polymorphic bands, down). 1 Serratula tinctoria 2 Klasea quinquefolia 3 K. oligocephala 4 K. kotschyi 5 K. serratuloides 6 K. erucifolia 7 K. lasiocephala 8 K. cerinthifolia 9 K. grandifolia 10K. radiata subsp. radiata11 K. hakkiarica 12 K. haussknechtii 13 K. coriaceae 14K. radiata subsp. radiata15 K. kurdica 16 K. bornmuelleri 17 Centaurea ptosimopappoides 18 C. straminicephala 19 Jurinea cataonica, M: marker.

A total of 15 Klasea, 1 Serratula, 1 Jurinea and 2 Centaurea taxa were used in the scoring analysis. The Jurinea and Centaurea taxa, which were used as the out-group, formed a cluster that was distinct from the Klasea and Serratula cluster in the constructed dendogram. Furthermore the Klasea and the Serratula taxa form clearly separate clusters among themselves (Figure 2).

Figure 2. 

Dendrogram showing genetic relationship of Klasea, Serratula, Centaurea and Jurinea species as shown using inter simple sequence repeats. (Serratula tinctoria, Klasea quinquefolia, K. oligocephala, K. kotschyi, K. serratuloides, K. erucifolia, K. lasiocephala, K. cerinthifolia, K. grandifolia, K. radiata subsp. radiata, K. hakkiarica, K. haussknechtii, K. coriaceae, K. radiata subsp. radiata, K. kurdica, K. bornmuelleri, Centaurea ptosimopappoides, C. straminicephala, Jurinea cataonica)

The Klasea radiata subsp. radiata and Klasea radiata subsp. biebersteiniana taxa were observed to be very closely positioned in the dendogram. The K. kotschyi, K. hakkiarica and K. haussknechtii taxa, which have similar leaf characteristics, were also correlated in terms of their molecular data and were located in the same sub-cluster. K. coriaceae is a taxon, which spreads over distinct areas in the Eastern Anatolia and is distinguished owing to its distinctive height. The Klasea oligocephala and K. kurdica clustered together. The two taxa are very similar also in terms of morphological properties such as leaf, capitulum and pollen characteristics. K. serratuloides taxon has the largest capitulum among the genus. It has a similar profile to the K. radiata subspecies with respect to the leaf characteristics and the similarity of overspreading areas. Klasea serratuloides and K. radiata were also positioned close to one another on the dendogram.

K. lasiocephala is distinguished within the genus by its very short stems or the absent stems.. K. lasiocephala differs morphologically from other Klasea taxa in having absent or reduced stems and that it is also somewhat genetically distinct from other Klasea taxa, as the sole taxon in the cluster in which it is placed. The K. erucifolia and K. grandifolia taxa have similar leaf characteristics and were also located in the same sub-cluster owing to their molecular characteristics. K. bornmuelleri taxon does not have a morphologically close relative in the genus. Its position on the dendogram confirmed this classification. K. cerinthifolia is distinguished by its yellow flowers and semiamplexicaul leaf structure and was also molecularly identified to be distinct. All these findings were consistent with the morphological classifications made in the Flora of Turkey (Davis and Kupicha 1975; Dogan et al. 2012). Martins and Hellwig (2005) showed that Klasea and Serratula taxa to belong to separate clusters in a molecular study conducted using the ITS and ETS sequences. The same study reported shorter distances on the dendogram constructed based on molecular similarities for the taxa, which showed morphological similarities.

The inspection of the dendogram indicated that molecularly similar taxa were also morphologically similar. This separation was also shown in the PCA plot (Figure 3).

Figure 3. 

Principal co-ordinate analysis (PCA) of Klasea, Serratula, Centaurea and Jurinea species. 1 Serratula tinctoria 2 Klasea quinquefolia 3 K. oligocephala 4 K. kotschyi 5 K. serratuloides 6 K. erucifolia 7 K. lasiocephala 8 K. cerinthifolia 9 K. grandifolia 10K. radiata subsp. radiata11 K. hakkiarica 12 K. haussknechtii 13 K. coriaceae 14K. radiata subsp. radiata15 K. kurdica 16 K. bornmuelleri 17 Centaurea ptosimopappoides 18 C. straminicephala 19 Jurinea cataonica

Our study has demonstrated that ISSR is a powerful tool in resolving the genetic relationships within problematic taxonomical entities. In conclusion, the morphologically close taxa were, in the molecular aspect, also located in the same clade. The genera used as out-groups (Serratula, Jurinea, and Centaurea) were clearly separate from the genus Klasea. According to our knowledge, this is the first report on the use of ISSR in Klasea.

This work was financially supported by The Scientific and Technical Research Council of Turkey (TUBITAK Project No. TBAG-109T243) and The Scientific Research Coordination Center (BAP) of Selcuk University (Project No. 11401048).