Karyological investigation of six Achillea L. (Asteraceae) species growing in Turkey

Abstract

The chromosome number and morphology in six species of the sections Babounya (DC.) O. Hoffm. and Achillea of the genus Achillea L. (Asteraceae) were investigated using karyological techniques. Sample plants and seeds of A. santolinoides Lag. subsp. wilhelmsii (K. Koch.) Greuter, A. falcata L., A. magnifica Hub. - Mor., A. pannonica Scheele, A. crithmifolia Waldst. & Kit. and A. nobilis L. subsp neilreichii (A. Kern.) Formánek were collected from natural habitats in 2005. The chromosome number found in six species was 2n = 18. All chromosomes had median point (M), median region (m), and submedian (sm) centromers. An increase in asymmetry was not observed in the karyotypes of the species studied. None of the studied species had any B chromosomes.

Keywords:

• Achillea
• Asteraceae
• chromosome number
• karyotypes
• mitosis
• Turkey

Introduction

The genus Achillea L. (Asteraceae) is widespread in Turkey, with 48 species (including 54 taxa) belonging to five sections, out of which 24 species (including 31 taxa) are endemic to Turkey (Huber-Morath 1975; Duman 2000; Danihelka 2001; Ehrendorfer and Guo 2005, 2006; Arabaci and Yildiz 2006a, 2006b; Celik and Akpulat 2008; Arabaci and Budak 2009).

The pollen morphology of 48 specimens of six species (nine taxa) of the genus Achillea L. sect. Achillea (Asteraceae), distributed in Turkey were investigated using light (LM) and scanning electron microscopy (SEM) (Akyalcin et al. 2011).

The basic chromosome number in Achillea is x = 9, with polyploidy occurring frequently. The karyology of the genus has been studied by several researchers and reported chromosome numbers include 2n = 18, 36, 54, and 72 (Tutin et al. 1980; Androschchuk and Kostinenko 1981; Dabrowska 1989, 1992; Maffei et al. 1993; Danihelka and Rotreklova 2000, 2001; Constantinidis and Kalpoutzakis 2005; Zhao et al. 2009). Somecytological studies have been published on the genus in Turkey: on A. multifida, A. setacea, and A. spinulifolia (Martin-Noguet 1969); A. sipikorensis and A. sintenisii (Turkoglu and Akpulat 2004); Achillea cucullata, A. vermicularis, A. monocephala, A. boissieri, A. santolina, A. gypsicola, A. goniocephala, and A. spinulifolia (Sahin et al. 2006); and A. biserrata, A. fraasii var. troiana, A. multifida, A. brachyphylla, A. pseudaleppica, A. cretica, A. latiloba and A. kotschyi subsp. kotschyi (Kiran et al. 2008). These indicated that the chromosome numbers and chromosome morphology were unknown for many of the Achillea species in Turkey. The aim of this study was to determine the chromosome number and morphology in further Achillea species present in Turkey.

Materials and methods

Plant samples and their seeds were collected from natural habitats in 2005, and the voucher specimens were deposited at the Inonu University Herbarium (INU). The localities are presented in the results according to the grid system adopted for the flora of Turkey by Davis (1975), geographical position, altitude and voucher number of the investigated samples. Seeds were germinated at 25°C on moist filter paper in Petri dishes. Actively-growing root tips, 1 cm in length, were excised from the germinating seeds and pretreated with aqueous colchicine (0.05%) for 3–3.5 h at room temperature. They were fixed with Carnoy (1:3 glacial acetic acid/absolute ethanol) for at least 24 h at 4°C, hydrolysed in 1 N HCl at 60°C for 15 min and then rinsed in tap water for a minimum of 3–5 min. Staining was carried out in Feulgen for 1 h and squash preparations were made with 45% acetic acid (Elci 1982). Microphotographs of good quality metaphase plates of each specimen were taken using an Olympus BX51 microscope and were recorded with a Canon A710 IS digital camera. Karyotypes were obtained from well-spread metaphase plates. Long arm, short arm and total length of each chromosome were measured and relative lengths, arm ratios and centromeric indices were determined. The chromosome nomenclature followed Levan et al. (1964). The intra-chromosomal asymmetry index (A1) was calculated according to the formula proposed by Romero Zarco (1986), while the inter-chromosomal asymmetry index (A2) was measured as the ratio of chromosome length/mean chromosome length.

Results

Achillea Sect. Babounya (DC.) O. Hoffm

Achillea santolinoides Lag. subsp. wilhelmsii (K. Koch.) Greuter

2n = 18; B7 Malatya: South of Develi village, rocks, 29.vi.2005, T. Arabacı 2074. The species is Irano-Turanian element. Its chromosome number is 2n = 18 and this is the first report on the chromosome number and morphology of this species. The ratio of the longest chromosomes to the shortest ones is 1.5:1. It consists of four median point (M) and five median region (m) chromosomes (Tables 1 and 2, Figures 1, 7A).

Table 1. Somatic chromosome number, ploidy level, karyotype formula, ranges of chromosome lengths, total karyotype length (TKL) and asymmetry index (A1, A2; Romero Zarco 1986) for the Achillea species investigated.

Taxon	2n	Ploidy level	Haploidal karyotype formula	Chromosome length range (μm)	TKL (μm)	A1	A2
A. santolinoides subsp. wilhelmsii	18	2x	4M+5m	10.76–16.72	116.84	0.11	0.14
A. falcata	18	2x	5M+3m+1sm	10.50–12.80	106.48	0.15	0.07
A. magnifica	18	2x	5M+2m+2sm	12.28–17.80	128.72	0.17	0.11
A. pannonica	18	2x	5M+3m+1sm	8.31–12.04	88.80	0.12	0.12
A. crithmifolia	18	2x	5M+4m	8.06–11.91	86.70	0.11	0.13
A. nobilis subsp . neilreichii	18	2x	4M+4m+1sm	8.70–11.26	88.43	0.15	0.10

Table 2. Karyomorphological parameters of species Achillea.

Pair no.	RL	AR	CI	Type	Pair no.	RL	AR	CI	Type
A. santolinoides subsp. wilhelmsii					A. falcata
I	14.3	1.23	44.79	m	I	12.02	1.00	50.00	M
II	11.84	1.25	44.43	m	II	12.02	1.00	50.00	M
III	11.84	1.00	50.00	M	III	11.77	1.00	50.00	M
IV	11.84	1.00	50.00	M	IV	11.65	1.45	40.69	m
V	11.17	1.26	44.10	m	V	10.87	1.41	41.45	m
VI	10.68	1.40	41.55	m	VI	10.81	1.00	50.00	M
VII	9.86	1.14	46.66	m	VII	10.69	1.96	33.71	sm
VIII	9.20	1.00	50.00	M	VIII	10.27	1.34	42.68	m
IX	9.20	1.00	50.00	M	IX	9.86	1.00	50.00	M
A. magnifica					A. pannonica
I	13.82	1.00	50.00	M	I	13.55	1.00	50.00	M
II	12.11	1.00	50.00	M	II	12.39	1.29	43.59	m
III	11.54	1.00	50.00	M	III	12.11	1.00	50.00	M
IV	11.19	1.27	43.99	m	IV	11.23	1.00	50.00	M
V	10.93	1.00	50.00	M	V	10.96	1.00	50.00	M
VI	10.64	2.24	30.80	sm	VI	10.66	1.24	44.56	m
VII	10.14	1.21	45.09	m	VII	9.89	1.86	34.92	sm
VIII	10.14	2.48	28.69	sm	VIII	9.79	1.00	50.00	M
IX	9.54	1.00	50.00	M	IX	9.35	1.28	43.80	m
A. crithmifolia					A. nobilis subsp . neilreichii
I	13.65	1.38	41.89	m	I	12.73	1.00	50.00	M
II	12.33	1.00	50.00	M	II	12.73	1.25	44.31	m
III	12.33	1.00	50.00	M	III	11.87	1.00	50.00	M
IV	11.44	1.36	42.28	m	IV	11.29	1.32	42.94	m
V	10.57	1.00	50.00	M	V	10.72	1.00	50.00	M
VI	10.57	1.00	50.00	M	VI	10.62	1.37	42.12	m
VII	10.12	1.29	43.48	m	VII	10.26	1.78	35.90	sm
VIII	9 70	1.00	50.00	M	VIII	9.90	1.32	43.03	m
IX	9.24	1.33	42.80	m	IX	9.83	1.00	50.00	M
Abbreviations: RL, relative length; AR, arm ratio (L/S); CI, centromeric index (100S/TL); m, median region; sm, submedian region; M, median point. Chromosome pairs are assigned roman numerals.

Figure 1–6 Metaphase chromosomes of Achillea species. (1) A. santolinoides subsp. wilhelmsii (2n = 18); (2) A. falcata (2n = 18); (3) A. magnifica (2n = 18); (4) A. pannonica (2n = 18); (5) A. crithmifolia (2n = 18); (6) A. nobilis subsp. neilreichii (2n = 18). Scale bar = 10 μm.

Figure 7 Haploid idiograms. (A) A. santolinoides subsp. wilhelmsii; (B) A. falcata; (C) A. magnifica; (D) A. pannonica; (E) A. crithmifolia; (F) A. nobilis subsp. neilreichii.

A falcata L.

2n = 18; C4 Mersin: from Silifke to Gülnar, 26 km, 17.viii.2005, T. Arabacı 2154. The species is Irano-Turanian element. Its chromosome number is 2n = 18 and this is the first report on the chromosome number and morphology of this species. The ratio of the longest chromosome to the shortest one is 1.2. It consists of five M, three m, and one submedian (sm) chromosomes (Tables 1 and 2, Figures 2, 7B).

A magnifica Hub.-Mor.

2n = 18; B7 Malatya: from Malatya to Hekimhan, 50. km, 1100 m, 3.vii.2005, T. Arabacı 2075. The species is endemic to the Irano-Turanian element of Turkey. Its chromosome numbers is 2n = 18 and this is the first report on the chromosome number and morphology of this species. The ratio of the longest chromosome to the shortest one is 1.4. It consists of five M, two m, and two sm chromosomes (Tables 1 and 2, Figures 3, 7C).

Sect. Achillea

A pannonica Scheele

2n = 18; A1 Kırklareli: from Kırklareli to Dereköy, 10 km, 200 m, 18.vii.2005, T. Arabacı 2131. The species is Euro-Sib. element. Its chromosome number is 2n = 18 and this is the first report on the chromosome number and morphology of this species. The ratio of the longest chromosome to the shortest one is 1.4. It consists of five M, three m, and one sm chromosomes (Tables 1 and 2, Figures 4, 7D).

A crithmifolia Waldst. & Kit.

2n = 18; A1 Tekirdağ: Ganos mountain, from Ucmakdere to Tekirdağ, 8 km, 350 m, calcareous rocks, 17.vii. 2005, T. Arabacı 2117. The species is Euro-Sib. element. Its chromosome number is 2n = 18 and this is the first report on the chromosome number and morphology of this species. The ratio of the longest chromosome to the shortest one is 1.4. It consists of five M, and four m chromosomes (Tables 1 and 2, Figures 5, 7E).

A nobilis L. subsp. neilreichii (A. Kern.) Formanek

2n = 18; A1 Kırklareli: from Kırklareli to Dereköy, 10 km, 200 m, 18.vii.2005, T. Arabacı 2129. The species is Euro-Sib. element. Its chromosome number is 2n = 18 and this is the first report on the chromosome number and morphology of this species. The ratio of the longest chromosome to the shortest one is 1.2. It consists of four M, four m, and one sm chromosomes (Tables 1 and 2, Figures 6, 7F).

Satellites were not observed in the karyotypes of six species.

Discussion

This study describes the karyology of six species of Achillea in Turkey, one of which is endemic to the examined region. No previous studies have been made on the chromosomes of these species. In all of the examined species the basic chromosome number was x = 9, with A. santolinoides subsp. wilhelmsii, A. falcata, A. magnifica, A. pannonica, A. crithmifolia and A. nobilis subsp neilreichii being diploid. These findings are in good agreement with the basic number and chromosome numbers given for Achillea species in previous studies (Tutin et al. 1980; Androschchuk and Kostinenko 1981; Dabrowska 1989, 1992; Maffei et al. 1993; Danihelka and Rotreklova 2001; Turkoglu and Akpulat 2004; Constantinidis and Kalpoutzakis 2005; Sahin et al. 2006; Kiran et al. 2008).

Samples of Achillea species with chromosomes numbers of 2n = 54 and 2n = 72 were reported by Danihelka and Rotreklova (2001) and Sahin et al. (2006), but this number was not observed in the species examined in the present study. B chromosomes, which are quite common within the A. millefolium group (Ehrendorfer 1959), further reported in A. pratensis by Danihelka and Rotreklova (2001) and in A. spinulifolia by Sahin et al. (2006), were not found in any of the Achillea species examined in the present study.

In general, there was no obvious difference of karyotype asymmetry among the studied species, all having a symmetrical karyotype structure, as most chromosomes had median and submedian centromeres (Romero Zarco 1986; Stebbins 1971).

The present study is only a part of a planned larger study on the karyological characteristics of all Achillea species in Turkey, so a comprehensive analysis of chromosomal similarities and differences among them will be done when our survey is completed.