Abstract: In this research, the chromosome number and morphology of M. trojana species are determined. Somatic chromosome number was counted as 2n = 12. The karyotype of this species consisted of four metacentric chromosome pairs and two submetacentric chromosomes. Chromosome length varies between 2.44-4.27 μm. The karyogram and idiogram were determined based on centromeric index and arranged in the decreasing size order.
INTRODUCTION
The genus of Matthiola R.Br. (Cruciferae) grows in Europe, Asia and Africa. The genus is represented approximately 50 species in the world and with ten species in Turkey (Heywood, 1993; Cullen, 1965; Dirmenci et al., 2006).
Matthiola trojana grows on the rocky slopes and limestones of Kazdağı National Park that is located in the district of Edremit (Balıkesir province) Nanekırı vicinity. This species is endemic to Turkey. Kaz Dağı, the highest mountain in the Biga peninsula called in antique ages as Ida Dağı, separates the Aegean region from the Marmara region.
Different forest formations, deep canyons, rocky cliffs, subalpine areas contribute with their different ecological conditions to the diversity of the flora within the region.
Among the forest vegetation of the national park; Pinus brutia, P. nigra, Abies nordmanniana subsp. equi-trojana taxa form the different forest zones, respectively the sea level to the mountain-peak. There are microclimate zones caused by special ecological systems in the isolated areas within the surroundings of Kazdağı. Therefore, a lot of different local taxa are endemic to Kazdağı. Some of them are as follows; Galium trojanum Ehrend., Digitalis trojana Ivan, Sideritis trojana Bornm., Armeria trojana Bokhari and Quezel, Hesperis theophrasti Borbas subsp. sintenisii Dvorak, Jasione idaea Stoj., Astragalus idae Sirj., Hieracium idae (Zahn) Sell and West, Abies nordmanniana (Stev.) Spach subsp. equi-trojani (Aschers. and Sint. ex Boiss.) Cood. and Cullen, Achillea fraasii Schultz Bip. var. trojana Aschers. and Heimerl, Centaurea odyssei Wagenitz, Cirsium steriolepis Petrax, Asperula sintenisii Achers ex Bornm, Ferulago idaea Özhatay et Akalın, Ferulago trojana E. Akalın and Pimenov., Allium kurtzianum (Aschers. and Sint. ex) Kollmann, Thymus pulvinatus Èelak, Hypericum kazdaghensis Gemici and Leblebici. Finally, M. trojana was introduced to the scientific world as a new taxon in 2006 from Kazdağı National Park.
The karyological research on the taxa of Matthiola showed genus the chromosome numbers to be 2n = 10, 12 and 14 (Dahlgren et al., 1971; Polatschek, 1983; Soliman and Parker, 1986; Izuzquiza, 1989; Canzobre and Castroviejo, 1993; Tiniakou, 1996; Soliman, 2002; Sánchez et al., 2004).
In this research, the chromosome number and morphology of the species has been studied for the first time.
MATERIALS AND METHODS
The seeds of M. trojana were obtained from Kazdağı Mountain in Turkey in 2006 (Fig. 1). In this research, the specimen which belongs to the genus M. trojana was collected and identified by Dr. Dirmenci. Voucher specimen and it seeds are kept in Balıkesir University, Education Faculty Herbarium. Seeds were germinated on moist filter paper in Petri dishes in room temperature. The other procedures followed are as described by Martin et al. (2007).
| Fig. 1: | Matthiola trojana distribution (▲) in Turkey |
| Table 1: | Measurements (μm) of somatic chromosomes in Matthiola trojana (m: metacentric; sm: submetacentric) |
| Total length of haploid complement: 20.59 μm | |
| Fig. 2: | Mitotic metaphase chromosomes of Matthiola trojana 2n = 12. Scale Bar: 10 μm |
RESULTS
The somatic chromosome number of Matthiola trojana were determined to be 2n = 12 (Fig. 2). The basic chromosome number for this species is x = 6. The total chromosome length is between 2.44-4.27 μm. Chromosomal classification was based on arm ratio and centromeric index as proposed by Levan et al. (1964).
| Fig. 3: | Karyogram of Matthiola trojana 2n = 12. Scale Bar: 10 μm |
| Fig. 4: | Haploid idiogram of Matthiola trojana 2n = 12. Scale Bar: 10 μm |
Detailed karyomorphological features are given in Table 1. The total length of the haploid set is 20.59 μm. As a classification result, the karyotype formula is 4m + 2sm. The idiogram and karyogram are given in Fig. 3 and 4.
DISCUSSION
The karyological research on taxa which belong to the genus of Matthiola showed that taxa chromosome numbers were 2n = 10, 12 and 14. Chromosome number in M. livida (Del.) DC. 2n = 10; in M. fruticulosa (L.) Maire subsp. fruticulosa, M. fruticulosa subsp. perennis (Conti) Ball., M. fruticulosa subsp. valesiaca (L.) Maire, M. parviflora (Schousb.) R. Br., M. longipetala (Vent.) DC. and M. bolleana Webb ex Christ. 2n = 12; in M. incana (L.) R. Br., M. sinuata (L.) R. Br., M. tricuspidata (L.) R. Br. and M. arabica Boiss., 2n = 14; (Dahlgren et al., 1971; Polatschek, 1983; Soliman and Parker, 1986; Izuzquiza, 1989; Canzobre and Castroviejo, 1993; Tiniakou, 1996; Soliman, 2002; Sánchez et al., 2004). In present study, the diploid chromosome numbers of M. trojana shows similarity with other species in regard to the diploid chromosome numbers.
In the other karyological study on M. odoratissima (Pall.) R.Br. species of Matthiola genus the somatic chromosome number was reported as 2n = 12 (Martin et al., 2007). In present study, the basic chromosome number is determined as x = 6 and the karyotype formula of both species as 4 m + 2 sm. In M. odoratissima the chromosome length ranges between 2.85-6.06 μm, in M. trojana 2.44-4.27 μm. The total haploid chromosome length of M. odoratissima is 25.10 μm, of M. trojana 20.59 μm. Present results are similar to those given in the literature.
Tiniakou (1996) reported M. longipetala to be in the family Matthiola genus and to have chromosome number 2n = 14 in his cytological study. This specie’s basic chromosome number is x = 7. In present study the diploid chromosome number of M. trojana is 2n = 12 and different from the basic chromosome number of M. longipetala which is x = 6.
The diploid chromosome number of Matthiola bolleana Webb ex Christ. and M. trojana was reported as 2n = 12 (Ardévol-Gonzáles et al., 1993). In present study, the diploid chromosome numbers of M. trojana shows similarity with other species in regard to the diploid chromosome numbers.
Soliman (2002) reported the karyotypes of the genus Matthiola, Erucaria, Cakile and Eremobium of the Cruciferae family, in his cytological study. In this study, diploid chromosome numbers of Matthiola is as follows; M. arabica 2n = 14, M. livida 2n = 10, 12 and M. longipetala 2n = 12. In present study, the diploid chromosome numbers of M. trojana shows similarity with other species in regard to the diploid chromosome numbers.
Soliman (2002) made a karyological study on three species belonging to genus Matthiola and determined the somatic chromosome number of Matthiola arabica species as 2n = 14 for. The karyotype formula of Matthiola is formed from 2M, 4nm, 4nsm (-), 2nsm (+) and 2nst (+) chromosome pairs. The somatic chromosome number of M. livida is 2n = 10 and its karyotype formula is declared as 2M, 4nm and 4nsm (-) and 2n = 12 had 2M, 4nm and 6nsm (-). The somatic chromosome number of M. longipetala is 2n = 12 and its karyotype formula is 2M, 6nm, 2nsm (-) and 2nsm (4) (Soliman, 2002). In this research, somatic chromosome number of M. trojana is defined as 2n = 12 and its karyotype formula is 4m + 2sm. This karyological results show similarities with M. longipetala species. When we compare the total chromosome length of Matthiola species, we can see some differences. For example, while the total chromosome length of M. arabica is 15.00 μm, it is for M. livida 11.77 μm, for M. longipetala 15.66 μm and for M. trojana 20.59 μm.
In this study, the chromosome number and karyomorphology of Matthiola trojana were determined for the first time. We hope that this study will contribute to the future karyological studies about the genus Matthiola.
ACKNOWLEDGMENTS
We express our thanks to TUBITAK (Project No. TBAG-1748) and Scientific Investigation Project to Coordinate of Selçuk University (project No: 05401046) for financial support. We express our gratitude to Harun Şimşek for proofreading and editing this text.