Regular Article
Karyological Investigation on Five Taxa of Bellevalia Lapeyr. (Asparagaceae) from Turkey
2019 年 84 巻 2 号 p. 173-177
詳細
2019 年 84 巻 2 号 p. 173-177
The somatic chromosome numbers and karyotypes were examined in five Bellevalia taxa including two endemic species of B. chrisii and B. gracilis distributed in Turkey. The chromosome numbers were determined as 2n=2x=8 in all studied taxa [B. chrisii Yıldırım & B. Şahin sp. nov., B. glauca (Lindl.) Kunth., B. gracilis Feinbrun, B. longipes Post, B. sarmatica (Pallas ex Georgi) Woronow]. The karyotype formula was determined as 2m+sm+st in B. chrisii and B. longipes, 3m+st in B. glauca, B. gracilis and B. sarmatica. The findings for each of the analyzed taxa are compared with the results of previous studies.
Bellevalia Lapeyr. is a genus of bulbous plants belonging to Asparagaceae, subfamily Scilloideae, tribe Hyacintheae (APG III 2009, Chase et al. 2009). The genus is distributed over the Mediterranean region from Morocco and Algeria eastwards to the Caucasus and Iran (Ozhatay et al. 1991, Bareka 2008, Jafari and Maassoumi 2008, Borzatti von Loewenstern et al. 2013, Karabacak et al. 2014, 2015) and 74 species are listed (Govaerts 1996). The largest number of species in the genus is found in the Irano–Turanian phytogeographical region (Feinbrun 1938). In Turkey, Bellevalia is represented by 28 taxa, 17 of which are endemic to the country (Wendelbo 1984, Davis et al. 1988, Ozhatay and Kultur 2006, Ozhatay et al. 2009, 2011, Guner et al. 2012, Uzunhisarcıklı et al. 2013, Gurdal et al. 2014, Karabacak et al. 2014, 2015).
The chromosome numbers (2n=8) of six Bellevalia species were published in the first supplement of the “Flora of Turkey” (Davis et al. 1988), five by Von Bothmer and Wendelbo (1981) and one by Wendelbo (1984). The second supplement (Ozhatay et al. 2000) contained chromosome numbers of 17 species. The chromosome numbers (2n=8, 12, 16, 20, 24, 31, 32, 35, e.g.) have been reported in nine Bellevalia species (Ozhatay et al. 1991, Johnson 1994, Ozhatay and Johnson 1996, Johnson and Brandham 1997, Dane 1999). Intraspecific polyploidy with the basic chromosome number of x=4 was also reported in B. edirnensis (Ozhatay et al. 1991). The polyploids of tetraploid (2n=16), hexaploid (2n=24) and octoploid (2n=32) and, also triploid (2n=12) and pentaploid (2n=20) are reported in some members of Bellevalia (Ozhatay et al. 1991).
The aim of this paper was to provide karyotypes data to clearly define chromosome number and karyotype for five Turkish Bellevalia species including B. chrisii for which no information about chromosomes is available.
Plant materials of five Bellevalia species, B. chrisii Yıldırım & B. Şahin sp. nov., B. glauca (Lindl.) Kunth., B. gracilis Feinbrun, B. longipes Post, B. sarmatica (Pallas ex Georgi) Woronow, were collected from natural habitats during the fruiting season between 2017 and 2018. Their localities, geographical position, altitude, and voucher number are presented in Table 1. The voucher specimens were deposited at the Herbarium of Firat University.
| Taxa | Locality | Voucher number |
|---|---|---|
| B. chrisii | B7/Malatya: Pütürge, Kubbe Mountain, 1900 m. | Dogan, 2052 |
| B. glauca | B7/Malatya: Doğanşehir, 1900 m. | Dogan, 2065 |
| B. gracilis | B7/Malatya: Pütürge, Nemrut-Büyüközü Village, 1600 m. | Dogan, 2053 |
| B. longipes | B7/Malatya: Darende, Irmaklı-Söğütlü, 1400 m. | Dogan, 2116 |
| B. sarmatica | B7/Malatya: Bölüklü Village, 1500 m. | Dogan, 2112 |
The karyological studies are conducted on the meristematic cells of bulbs. The bulbs were germinated at 25°C. The actively growing root tips were pretreated with 0.05% colchicine for 3–3.5 h at room temperature. Afterward, the root tips were fixed with Carnoy fixative (1 : 3 glacial acetic acid–absolute ethanol) for at least 24 h at 4°C, hydrolyzed in 1 M HCl at 60°C for 10–15 min, then rinsed in tap water for 3–5 min. Finally, they were stained in the Feulgen reagent for 1 h and mounted in 45% acetic acid (Kiran et al. 2012). Digital microphotographs from at least five well-spread metaphase plates were taken using an Olympus BX51 microscope and an Olympus Camedia C-4000 digital camera.
The number of somatic chromosomes, chromosome length range, haploid chromosome length, arm ratio, relative length, and karyotype formula were determined in this study were measured. Karyotype formula was determined based on the centromere position using a system of Levan et al. (1964). The ideograms of these taxa are arranged in decreasing lengths according to the chromosome size in the metaphase (Martin et al. 2009).
Karyotype asymmetry was determined by using various methods including total form percentage (TF%), percentage karyotype asymmetry index (AsK%), index of karyotype symmetry (Syi), index of chromosome size resemblance (Rec) and the degree of asymmetry for karyotypes (A) (Huziwara 1962, Arano 1963, Greilhuber and Speta 1976, Venora et al. 2002, Watanabe et al. 1999). While the intrachromosomal asymmetry index (A1) and the interchromosomal asymmetry index (A2) was calculated according to the formula proposed by Romero Zarco (1986). Also, karyotype evolution was speculated based on Stebbins’ classification (1971).
The characteristics of somatic chromosomes of examined five Bellevalia taxa are given below.
B. chrisii Yıldırım & B. Şahin is a local endemic species that is restricted to the Pötürge district in Malatya, eastern Anatolia. Plants collected was on mountain steppe at 1900–2000 m (Table 1) belonging to the Irano–Turanian floristic region. The somatic chromosome number of this species was found to be 2n=8 in all five plants (Fig. 1a). The chromosome length ranges 10.64 to 17.04 µm and the total length of the haploid complement was 53.10 µm. The haploid karyotype consists of two metacentric (m), one submetacentric (sm) and one subtelocentric (st) chromosomes. Arm ratios are 1.27–3.57 and relative lengths are 20.04–32.09% (Table 2). Idiogram is given in Fig. 2a. This species of karyology was determined for the first time.
| Taxa | 2n | Chromosome length (µm) | Haploid chromosome length (µm) | Arm ratio | Relative length (%) | Karyotype formula | |||
|---|---|---|---|---|---|---|---|---|---|
| Min | Max | Min | Max | Min | Max | ||||
| B. chrisii | 8 | 10.64 | 17.04 | 53.10 | 1.27 | 3.57 | 20.04 | 32.09 | 2m+sm+st |
| B. glauca | 8 | 10.66 | 18.38 | 56.84 | 1.24 | 3.43 | 18.75 | 32.33 | 3m+st |
| B. gracilis | 8 | 12.21 | 20.45 | 63.19 | 1.21 | 3.46 | 19.32 | 32.36 | 3m+st |
| B. longipes | 8 | 9.97 | 18.46 | 54.00 | 1.29 | 3.86 | 18.46 | 34.18 | 2m+sm+st |
| B. sarmatica | 8 | 8.70 | 14.81 | 45.95 | 1.26 | 3.69 | 18.93 | 32.24 | 3m+st |
B. glauca (Lindl.) Kunth. is a new record of Turkey and is restricted to the Kubbe Pass in Malatya, eastern Anatolia. It grows on mountain steppe at 2000 m. It is an element belonging to the Irano–Turanian floristic region. The somatic chromosome number of this species was found to be 2n=8 in all five plants (Fig. 1b) and supported the previous report (Nersesian 2001). The chromosome length ranges 10.66 to 18.38 µm, and the total length of the haploid complement was 56.84 µm. The haploid karyotype consists of three m and one st chromosomes. Arm ratios are 1.24–3.43 and relative lengths are 18.75–32.33% (Table 2). Idiogram is given in Fig. 2b.
B. gracilis Feinbrun is an endemic, and one of the Irano–Turanian element. This taxon distributed stony hilltops, eroded shaley slopes in Pinus brutia forest, fields, between 600 and 1500 m (Table 1). The somatic chromosome number of this species was found to be 2n=8 in all five plants (Fig. 1c). Our observation confirmed diploid number but not tetraploid (Kayiran and Ozhatay 2017) and B chromosomes (Ozhatay et al. 1991). The chromosome length ranges 12.21 to 20.45 µm, and the total length of the haploid complement was 63.19 µm. The haploid karyotype consists of three m and one st chromosomes. Chromosome arm ratios are 1.21–3.46 and relative lengths are 19.32–32.36% (Table 2). Idiogram is given in Fig. 2c.
B. longipes Post distributes fields, c. 1050 m (Table 1). It is an element belonging to the Irano–Turanian floristic region. The somatic chromosome number of this species was found to be 2n=8 in all five plants (Fig. 1d) supporting the previous report (Von Bothmer and Wendelbo 1981). The chromosome length ranges 9.97 to 18.46 µm, and the total length of the haploid complement was 54.00 µm. The haploid karyotype consists of two m, one sm, and one st chromosomes. Arm ratios are 1.29–3.86 and relative lengths are 18.46–34.18% (Table 2). Idiogram is given in Fig. 2d.
B. sarmatica (Pallas ex Georgi) Woronow distributed fallow fields, banks, steppe, between 870 and 1900 m (Table 1). The somatic chromosome number was found to be 2n=8 (Fig. 1e), as in many works of literature (Zakhariyeva and Makushenko 1969, Von Bothmer and Wendelbo 1981, Pogosyan and Torosian 1983, Ozhatay et al. 1991, Johnson 2003). The chromosome length ranges 8.70 to 14.81 µm and the total length of the haploid complement was 45.95 µm. The haploid karyotype consists of three m and one st chromosomes. Arm ratios are 1.26–3.69 and relative lengths are 18.93–32.24% (Table 2). Idiogram is given in Fig. 2e.
The somatic chromosome numbers of all five taxa Bellevalia in this study were determined as 2n=2x=8. Karyotype analysis showed that chromosome complements were composed of m, sm and st chromosomes. The Bellevalia is characterized by a basic chromosome number x=4, most representatives of the genus have eight chromosomes in the diploid complement. It is evident from earlier studies that the karyotype in Bellevalia is more or less stable, showing a “typical” karyotype occurring in almost all species studied (Feinbrun 1938, Levan et al. 1964, Von Bothmer and Wendelbo 1981, Ozhatay et al. 1991, Johnson and Brandham 1997). Chromosome lengths show wide variations among species. The mean chromosome length varies between 8.70 and 20.45 µm. The shortest mean chromosome length is seen in B. sarmatica while the longest mean chromosome length was in B. gracilis. Haploid chromosome length ranges from 45.95 to 63.19 µm, and relative lengths from 18.46 to 34.18% (Table 2). The intrachromosomal asymmetry index (A1) varies from 0.38 in B. gracilis to 0.43 in B. sarmatica. Interchromosomal asymmetry index (A2) ranges from 0.21 in B. chrisii to 0.28 in B. longipes (Table 3).
| Taxa | TF% | As K% | Syi | Rec | A | A1 | A2 | Stebbins’s classification |
|---|---|---|---|---|---|---|---|---|
| B. chrisii | 35.50 | 64.49 | 55.05 | 77.88 | 0.29 | 0.42 | 0.21 | 2A |
| B. glauca | 36.57 | 63.42 | 57.66 | 77.31 | 0.26 | 0.39 | 0.23 | 2A |
| B. gracilis | 37.07 | 62.92 | 58.92 | 77.24 | 0.38 | 0.38 | 0.22 | 2A |
| B. longipes | 35.40 | 64.59 | 54.81 | 84.51 | 0.29 | 0.42 | 0.28 | 2A |
| B. sarmatica | 35.28 | 64.71 | 54.53 | 77.53 | 0.29 | 0.43 | 0.23 | 2A |
In this study, chromosome numbers and karyotypes of five Bellevallia taxa were established and will contribute to further studies on the karyotype properties and implications on systematic of Bellevallia taxa from Turkey.
