Chromosome numbers of taxa of the genus Jurinea Cass. (Asteraceae) in Iran

Abstract

In this study, somatic chromosome numbers of 27 Jurinea Cass. taxa (25 species and two subspecies), collected from different localities in Iran, were counted. Apart from Jurinea macrocephala DC. and J. pulchella DC. these are reported here for the first time. Except for J. eriobasis DC. with 2n = 36 and J. gedrosiaca Bornm. with 2n = 32 all the materials studied showed a somatic number of 2n = 34. Regarding the dysploidy observed in this genus two theories based on a decrease in aneuploidy and a polyploidy pillar complex are justified and discussed here.

Keywords:

• Asteraceae
• Cardueae
• chromosome number
• Iran
• Jurinea Cass

Introduction

Plant taxonomy is initially based on morphological characteristics. Because these features vary, other characters such as chromosome number and chromosome morphology have been increasingly used in plant taxonomy. These data are also important to elucidate the origin, speciation and phylogenetic relationships of plants (Stebbins 1971; Cai et al. 2004; Pavlova and Tosheva 2005). In plants, mechanisms such as chromosomal rearrangements and changes in the basic chromosome number or in ploidy level can usually be accompanied by diversification and sometimes speciation (Levin 2002). Determining chromosome number in many populations throughout the distributional range of a given species represents a primary and essential step, in which events such as dysploidy, aneuploidy or polyploidy can be revealed (Sánchez-Jiménez et al. 2009).

The Asteraceae is the largest plant family and comprises more than 1600 genera and 23,000 species (Anderberg et al. 2007; Funk et al. 2009). Its many genera and species, its worldwide distribution and the fact that it comprises many useful plants have made it the subject of many karyological studies (Watanabe 2013).

For about 60% of the genera of Asteraceae chromosome counts have been reported (Akhtar 2005). Many genera surveyed are monobasic for x = 9 and x = 7, 25 genera appear to have more than one base number, and 18 of these have a base number of 8 or 9. The Old World genera have not been surveyed as extensively as New World genera; reports are available for 46% of genera, and x = 8 is predominant. Approximately 26% of the genera are monobasic for x = 9; a considerable number of the genera having more than one base number do not include x = 9 which was considered to be the ancestral number in Asteraceae (Stebbins 1971; Solbrig 1977; Stuessy 1977): however the most common is x = 8 which more likely is to be the ancestral base number for this family. Variation in chromosome number is probably through hybridization, euploidy and aneuploidy in Asteraceae (Häffner 2000; Funk et al. 2009). It is obvious by the data that the tribe Cardueae could be divided into two phyletic groups: a large group with x = 9 and 8, and a smaller group of genera with x = 6, 5 and 4. Nevertheless, the chromosome numbers range considerably among different genera of the tribe which can be correlated to relevant morphological variability; these characters are proved to be useful in the classification of this tribe. Chromosomal features are fundamental to have a better understanding of the relationships in Cardueae, particularly at the generic level (Akhtar 2005).

The monophyletic tribe Cardueae is constituted of five subtribes, namely Carduinae Cass., Centaureinae (Cass.) Dumort., Carlininae (Cass.) Dumort., Cardopatiinae Less., and Echinopinae (Cass.) Dumort (Susanna et al. 2006; Anderberg et al. 2007). Jurinea Cass. is a genus located within Carduinae. It was described based on two new species transferred from Serratula L. and Carduus L. (Cassini 1819). The genus comprises perennial herbs or rarely shrubby plants with purple, red, pink or whitish florets and involucres of linear to lanceolate phyllaries, the achenes are tetragonal with a distal corona around their apexes (Kožuharov 1976; Rechinger and Wagenitz 1979). Jurinea Cass. is a taxonomically complex genus comprising c.100 (Strid 1991) to 200 species (Susanna et al. 2006) or even 300 species (Iljin 1962). Native distribution of this genus covers Central Asia, Iran, Turkey and the Mediterranean region (Häffner 2000; Funk et al. 2009).

Jurinea is represented by 37 species in the Flora Iranica area, of which 25 species grow in Iran from which 22 are endemic (Rechinger and Wagenitz 1979). The number and position of taxa change every year, with new species being described, or some of the taxa recently displaced (Akhani 1996; Ghahreman and Mirtadzadini 2000; Mehregan and Assadi 2009; Mirtadzadini et al. 2011). So, from previous studies and our investigation, there are 26 species of Jurinea in the political boundary of Iran at present Rechinger & Wagenitz (1979).

Based on chromosomal information found in the literature (Baksay 1956; Kuzmanov and Kožuharov 1967; Borhidi 1968; Chouksanova et al. 1968; Küpfer 1969a, 1969b; Holub et al. 1971; Kuzmanov and Ancev 1973; Lungeanu 1973; Kuzmanov and Georgieva 1977; Humphries et al. 1978; Kieft and Loon 1978; Chichiricco et al. 1979; Sokolovskaia and Probatova 1980; Vir and Kachroo 1985; Kuzmanov et al. 1986; Magulaev 1976, 1982, 1986; Jee et al. 1989; Kochjarova 1990; Blanca and Cueto 1992; Kuzmanov et al. 1990, 1993; Vogt and Oberprieler 1993; Diaz De La Guadia 1995; Gagnidze and Gviniashvili 1997; Dogan et al. 2009, 2010), it is evident that Jurinea is poorly known cytologically. No cytotaxonomic record of this genus has been reported from Iran so far.

The main objective of this study is a first step to reveal cytological information about the described Jurinea taxa from Iran and enlarge the chromosomal data in the genus. We believe this study will play a positive role in resolving the morphologically unsolved problems of this taxonomically complex genus.

Materials and methods

The examined plant materials are presented in Table 1. Plant materials were collected from different localities in Iran, in 2008–2012. Voucher specimens are deposited in the herbarium of Department of Biology at the University of Isfahan (HUI).

Table 1. List of Jurinea taxa studies (all samples were collected by Parishani & Mirtadzadini).

No	Taxon	Collection site	Altitude (m)	Coordinates	Herbarium vouchers
1	Jurinea antunowi C. Winkl.	Khorasan, Bojnord to Ashkhaneh, Pish Qalae to Raz, Hesarcheh-Kheshtly frontier locality	1020	N 38°09′45″	18069
				E 56°23′56″
2	J. bungei Boiss.	Isfahan, Shah Reza to Abadeh, Amin Abad	1750	N 31°40′25″	18070
				E 50°05′50″
3	J. catharinae Iljin	Khorasan, Qochan to Dare Gaz, 5 km after Sang Sorakh	928	N 37°37′01″	18071
				E 58°45′41″
4	J. cordata Boiss. & Hasskn. ex Boiss.	Kermanshah, Sonqor, Dalakhani Mountain	2527	N 34°42′05″	18072
				E 47°37′13″
5	J. dumulosa Boiss.	Kerman, North of Zarand, Pabdana defile	2250	N 31°13′45″	18073
				E 56°28′47″
6	J. eriobasis DC.	Isfahan, Damaneh	2600	N 32°59′52″	18074
				E 50°29′10″
7	J. gabrieliae Bornm.	Khorasan, Birjand to Mod, Khorashad village, near Baqran Mountain	1950	N 32°45′10″	18075
				E 59°23′15″
8	J. gedrosiaca Bornm.	Kerman, Bam to Bervat, near Bam, Abgarm Seiedi road	580	N 28°58′55″	18076
				E 58°18′58″
9	J. giviensis Mirtadz.	Azarbaijan, Khalkha to Ardebil, 95 km Ardebil, Givi	1576	N 37°42′10″	18077
				E 48°26′29″
10	J. heterophylla Jaub. & Spach	Tehran, Karaj to Qazvin, toward Taleqan, 5 km after Samq Abad Village	2131	N 36°06′54″	18078
				E 50°39′25″
11	J. inuloides Boiss. & Hausskn. ex Boiss.	Kurdistan, Marivan to Nosod, Tate defile	2441	N 35°16′30″	18079
				E 46°10′39″
12	J. kopetensis Rech. f.	Khorasan, Mashhad to Kallat Naderi, 105 km to Kllat Naderi	1674	N 36°35′48″	18080
				E 59°53′34″
13	J. leptoloba DC.	Azarbaijan, Tabriz to Marand, Sofian	1458	N 38°17′10″	18081
				E 45°58′54″
14	J. macrocephala DC. subsp. elbursensis Wagenitz	Tehran, Karaj to Qazvin, toward Kohsar, Dobarzan Village	1699	N 35°59′52″	18082
				E 50°50′04″
15	J. macrocephala DC.	Isfahan, Chadegan to Saman, 3 km after Sadeq Abad	1920	N 32°36′26″	18083
				E 50°51′35″
16	J. meda Bornm.	Isfahan, Khunsar	2650	N 33°12′56″	18084
				E 50°19′53″
17	J. mobayenii Ghahr. & Mirtadz.	Kerman, North of Baft, Goqer village, Gonbadan Preserve	2600	N 29°27′30″	18085
				E 56°26′30″
18	J. monocephala Aitch. & Hemsl. subsp. sintenisii (Bornm.)Wagenitz	Khorasan, Qochan to Dare Gaz, 80 km to Dare Gaz Dor Badam	2250	N 37°26′13″	18086
				E 58°35′39″
19	J. multicaulis DC.	Azarbaijan, Tabriz to Vinar, around Achi-Chai River	1502	N 38°07′48″	18087
				E 46°30′48″
20	J. prasinophylla Rech. f.	Isfahan, Damaneh	2610	N 32°59′54″	18088
				E 50°29′07″
21	J. proteoides Boiss. & Hausskn. ex Boiss.	Bakhtiari, Ardell, Davazdah Emam Village	1807	N 31°58′50″	18089
				E 50°35′45″
22	J. pulchella DC.	Azarbaijan, Mako to Bazorgan, the east of Bazorgan custom	1462	N 39°24′22″	18090
				E 44°23′37″
23	J. radians Boiss.	Semnan, Semnan to Damghan, Ahowan defile	1930	N 35°44′39″	18091
				E 53°40′58″
24	J. ramosissima DC.	Isfahan, Isfahan University	1630	N 32°40′25″	18092
				E 51°36′20″
25	J. sharifiana Rech. f. & Esfand.	Semnan, Shahrod to Azad shahr, Abr Village	2250	N 36°45′37″	18093
				E 55°08′43″
26	J. stenocalathia Rech. f.	Yazd, Taft to Deh Shir, Dareh Zereshk Village	2300	N 31°28′30″	18094
				E 53°42′46″
27	J. viciosoi Pau	Bakhtiari, Ardell to Samsami, Cheri defile	2905	N 32°10′19″	18095
				E 50°10′36″

Chromosome counts were made on somatic metaphases using standard squash techniques. Mitotic chromosome preparations were obtained from the root-tip of germinating seeds collected in the wild. Root-tip meristems were obtained by germinating seeds on wet filter paper in Petri dishes at approximately 18°C. Actively growing roots were excised in the morning, when they were about 0.5–1 cm long. Times from 8 am to 4 pm were tested and the best results were obtained at 9.30 am.

Root tips of 1–2 cm were cut off and pretreated with saturated solution of α-bromo-naphthalene at 4°C for 16 h, fixed in fresh Carnoy’s solution (3:1 ethanol:glacial acetic acid) for 24 h and stored at 4°C until use. Root tips were washed in distilled water to remove the fixative, hydrolyzed in 1N HCl for 20–25 min at room temperature and stained in 1% aceto-orcein at least for 8 h (Sharma and Sharma 2001; Singh 2002; Martin et al. 2006; Dogan et al. 2009). Squashing was done in a drop of acetic acid 45%. The best metaphase plates were photographed using a BX40 microscope (Olympus, Tokyo, Japan) with digital camera attachment. To assess the existence of previously published chromosome counts in the studied species, we used the chromosome number databases of plant chromosome numbers cited by Dogan et al. (2009), as well as the online chromosome number databases Index to Plant Chromosome Numbers (Missouri Botanical Garden, http://www.tropicos.org/Project/IPCN) and Index to Chromosome Numbers in Asteraceae (Watanabe 2013).

Results and discussion

Many taxonomic and phylogenetic problems concerning the genus Jurinea have not been resolved till now. However, more extensive karyologic and genomic data are needed in addition to taxonomic and phylogenetic criteria to throw some light on these problems.

Our observations of all the Iranian Jurinea species revealed 2n = 34 to be the most common diploid number, and only two species had different numbers (2n = 32 and 2n = 36). The results are given below based on the sectional position of the species and the endemism reports are substantially according to Flora Iranica (Rechinger and Wagenitz 1979).

Sect. Corymbosae Benth. in Benth. et Hook. F., Gen. Plant. 2: 473, 1873

1. J. pulchella DC.

This species is a diploid with 2n = 34 (Table 1, Figure 1-1). Our record of 2n = 34 for this species confirms the previous determination on specimens from Turkey reported by Dogan et al. (2009).

Figure 1. (Colour online) Somatic metaphases: 1-1, Jurinea pulchella 2n = 34; 1-2, J. leptoloba 2n = 34; 1-3, J. heterophylla 2n = 34; 1-4, J. giviensis 2n = 34; 1-5, J. gedrosiaca 2n = 32; 1-6, J. macrocephala 2n = 34; 1-7, J. macrocephala subsp. elbursensis 2n = 34; 1-8, J. multicaulis 2n = 34; 1-9, J. proteoides 2n = 34; 1-10, J. cordata 2n = 34; 1-11, J. inuloides 2n = 34; 1-12, J. viciosoi 2n = 34; 1-13, J. meda 2n = 34; 1-14, J. prasinophylla 2n = 34; 1-15, J. sharifiana 2n = 34.

2. J. leptoloba DC.

This species is endemic to Iran (Rechinger and Wagenitz 1979). The somatic chromosome number is 2n = 34 (Table 1, Figure 1-2). This is the first chromosome count for this species.

3. J. heterophylla Jaub. et Spach

The chromosome number of this species is determined as 2n = 34 (Table 1, Figure 1-3). To our knowledge, this is the first report for this taxon. This taxon is endemic to Iran (Rechinger and Wagenitz 1979).

4. J. giviensis Mirtadz.

This taxon is endemic to Iran and is found in a limited area of Ardebil province (Mirtadzadini et al. 2011). The somatic chromosome number is 2n = 34 (Table 1, Figure 1-4). According to our data, this is the first chromosome count for this species.

5. J. gedrosiaca Bornm.

This taxon is endemic to Iran (Rechinger and Wagenitz 1979). The chromosome number in this species showed 2n = 32 (Table 1, Figure 1-5). According to our data, this is the first chromosome count for this species.

Sect. Derderia (Jaub. et Spach) Boiss. in Boiss. Fl. Or. 3: 568, 1875

6. J. macrocephala DC.

This taxon exhibited 2n = 34 (Table 1, Figure 1-6). Our record of 2n = 34 for this species confirms the previous determination on specimens from Turkey reported by Dogan et al. (2009).

7. J. macrocephala DC. subsp. elbursensis Wagenitz

This taxon is endemic to Iran and is found in a limited area of Karaj and Qazvin (Rechinger and Wagenitz 1979). It exhibited 2n = 34 (Table 1, Figure 1-7). The chromosome number of the taxon is given here for the first time.

8. J. multicaulis DC.

This taxon is endemic to Iran (Rechinger and Wagenitz 1979). The chromosome number in this species showed 2n = 34 (Table 1, Figure 1-8). According to our data, this is the first chromosome count for this species.

9. J. proteoides Boiss. et Hausskn. ex Boiss.

This taxon exhibited 2n = 34 (Table 1, Figure 1-9). This species is endemic to Iran and is found in a limited area of Chaharmahal-Bakhtiari province (Rechinger and Wagenitz 1979). This is the first chromosome count for this species.

10. J. cordata Boiss. et Hausskn. ex Boiss.

The somatic chromosome number of this taxon is 2n = 34 (Table 1, Figure 1-10). This taxon is endemic to Iran (Rechinger and Wagenitz 1979). The chromosome number of the taxon is reported here for the first time.

11. J. inuloides Boiss. et Hausskn. ex Boiss.

This taxon is endemic to Iran (Rechinger and Wagenitz 1979). It exhibited 2n = 34 (Table 1, Figure 1-11). This is the first chromosome count for this species.

Sect. Bellae Iljin, Fl. URSS. 27:720 (1962)

12. J. viciosoi Pau

This is an Iranian endemic and perennial species that grows on rocky slopes, road sides and stony pastures of Bazoft’s altitudes (Rechinger and Wagenitz 1979). It is determined that the somatic chromosome number is 2n = 34 (Table 1, Figure 1-12). According to our data, this is the first chromosome count for this species.

13. J. meda Bornm.

This taxon is endemic to Iran (Rechinger and Wagenitz 1979). The chromosome number in this species is 2n = 34 (Table 1, Figure 1-13). The chromosome number of the taxon is given here for the first time.

14. J. prasinophylla Rech. f.

This taxon possessed 2n = 34 chromosomes (Table 1, Figure 1-14). This species is endemic to Iran (Rechinger and Wagenitz 1979). This is the first chromosome count for this species.

15. J. sharifiana Rech. f. et Esfand.

This taxon is endemic to a limited area in north-east Semnan Province (Rechinger and Wagenitz 1979). The chromosome number in this species was 2n = 34 (Table 1, Figure 1-15). According to our data, this is the first chromosome count for this species.

Sect. Penduliflorae Iljin, Fl. URSS. 27:721 (1962)

16. J. kopetensis Rech. f.

The chromosome number of this species was determined to be 2n = 34 (Table 1, Figure 1-16). This is the first report on the chromosome number of the species. It is endemic to Iran (Rechinger and Wagenitz 1979).

Figure 1. (Continued) 1-16, Jurinea kopetensis 2n = 34; 1-17, J. radians 2n = 34; 1-18, J. monocephala subsp. sintenisii 2n = 34; 1-19, J. dumulosa 2n = 34; 1-20, J. antunowi 2n = 34; 1-21, J. catharinae 2n = 34; 1-22, J. ramosissima 2n = 34; 1-23, J. gabrieliae 2n = 34; 1-24, J. stenocalathia 2n = 34; 1-25, J. eriobasis 2n = 36; 1-26, J. mobayenii 2n = 34; 1-27, J. bungei 2n = 34.

17. J. radians Boiss.

This taxon is endemic to eastern Iran (Rechinger and Wagenitz 1979). It possessed 2n = 34 chromosomes (Table 1, Figure 1-17). The chromosome number of the taxon is given for the first time.

Sect. Suffrutices Iljin: Fl. URSS. 27: 721, 1962

18 J. monocephala Aitch. et Hemsl. subsp. sintenisii (Bornm.) Wagenitz

This taxon is distributed in Iran and Turkmenistan (Rechinger and Wagenitz 1979). The chromosome number of this species was determined to be 2n = 34 (Table 1, Figure 1-18). This is the first report on the chromosome number of the species.

Sect. Stechmannia (DC.) Boiss., Fl. Or. 3: 568, 1875.

19. J. dumulosa Boiss.

This taxon is a common species endemic to Iran and Afghanistan (Rechinger and Wagenitz 1979). It possessed 2n = 34 chromosomes (Table 1, Figure 1-19). According to our data, this is the first chromosome count for this species.

20. J. antunowi C. Winkl.

This taxon is distributed in Kopet Dagh region of Turkmenistan and limited area of north-east Iran (Rechinger and Wagenitz 1979; Akhani 1996).The chromosome number of this species was determined to be 2n = 34 (Table 1, Figure 1-20). This is the first report on the chromosome number of the species.

21. J. catharinae Iljin

This taxon is endemic to north-east Iran (Rechinger and Wagenitz 1979). The chromosome number in this species showed 2n = 34 (Table 1, Figure 1-21). According to our data, this is the first chromosome count for this species.

22. J. ramosissima DC.

This species is an endemic taxon to central and eastern Iran and a limited area of south-west Afghanistan (Rechinger and Wagenitz 1979). The chromosome number of this species was determined to be 2n = 34 (Table 1, Figure 1-22). This is the first report on the chromosome number of the species.

23. J. gabrieliae Bornm.

This species is endemic to Iran (Rechinger and Wagenitz 1979). It was determined that the somatic chromosome number is 2n = 34 (Table 1, Figure 1-23). This is the first chromosome count for this species.

24. J. stenocalathia Rech. f.

The chromosome number of this species was determined to be 2n = 34 (Table 1, Figure 1-24). This is the first report on the chromosome number of the species. It is endemic to Iran (Rechinger and Wagenitz 1979).

25. J. eriobasis DC.

This species is endemic to Iran (Rechinger and Wagenitz 1979). Its somatic chromosome number was determined as 2n = 36 (Table 1, Figure 1-25). This is the first count for this species.

Indefinite section

26. J. mobayenii Ghahr. & Mirtadz.

The chromosome number of this species was determined to be 2n = 34 (Table 1, Figure 1-26). This is the first report on the chromosome number of the species. This species is distributed in a limited region of south-west Kerman province (Ghahreman and Mirtadzadini 2000).

27. J. bungei Boiss.

This species is endemic and it is distributed only in the central regions of Iran (Rechinger and Wagenitz 1979). The chromosome number in this species is 2n = 34 (Table 1, Figure 1-27). According to our data, this is the first chromosome count for this species.

In spite of our intensive exploration around the country, we could not find Jurinea ancyrensis Bornm. [belonging to Sect. Derderia (Jaub. et Spach) Boiss.] that Rechinger and Wagenitz (1979) said was in Iran. We explored the mentioned places and found taxa similar to J. multicaulis DC. and J .macrocephala DC.

In the present study, all the Jurinea species studied were determined to be comprised of a basic chromosome number of x = 17 with the exception of two species (J. gedrosiaca with x = 16 and J. eriobasis with x = 18). Although it was rare, during cytogenetic analyses a few cells revealed polyploidy in some of the preparations. However, in 11 of the species tetraploid cells (2n = 4x = 68) were determined in the same preparations where diploid chromosomes (2n = 2x = 34) were counted (mixoploidy). They were: J. bungei, J. inuloides, J. leptoloba, J. macrocephala DC. subsp. elbursensis, J. monocephala, J. pulchella, J. radians, J. sharifiana, J. eribasis, J. viciosoi and J. giviensis (Figure 2-1 to 2-6).

Figure 2. (Colour online) Polyploidy in somatic metaphases: 2-1, Jurinea monocephala subsp. sintenisii 2n = 68; 2-2, J. radians 2n = 68; 2-3, J. viciosoi 2n = 68; 2-4, J. eriobasis 2n = 72; 2-5, J. bungei 2n = 68; 2-6, J. macrocephala subsp. elbursensis 2n = 68.

Since the level of chromosome number variation of Jurinea is low (mostly 2n = 34), it indicates that chromosomal counting is not a good parameter to use in distinction of the Jurinea species. Some species of Jurinea are dysploids, with 2n = 24, 30, 32, 35, 36 and 58 (such as J. gedrisiaca with 2n = 32 and J. eriobasis with 2n = 36 in the present study; Missouri Botanical Garden, http://www.tropicos.org/Project/IPCN; Watanabe 2013). Due to the morphological characters of J. gedrosiaca (it is very similar to Tricholepis species) and its chromosome number, it is suggested that this taxon belongs to the genus Tricholepis rather than Jurinea. Based on the absence of spiny phyllary in involucre and white hair cover and also diploid chromosome number in J. eriobasis, it can separated from section Stechmannia (DC.) Boiss.

Although Dogan et al. (2011) provided, as well as the karyotypes, haploid idiograms of each chromosome count for the Turkish Jurinea species, the somatic chromosomes of most Jurinea species examined here were very small and it was difficult to determine the exact positions of the centromere. Consequently it was not possible to determine the precise chromosomal morphologies. Based on the chromosome counts made in this study we found x = 17 to be the most frequent number among the Iranian Jurinea species, which is in accordance with Dogan et al. (2009) who reported 2n = 34 for Turkish taxa. In addition, on the basis of the reports indexed in Watanabe (2013), 2n = 34 is the most common number in this genus (Table 2). Due to the predominance of dysploidy in Astreaceae (Anderberg et al. 2007; Funk et al. 2009) the taxonomic boundary of the genus Jurinea and its chromosomal formula should be interpreted based on a kind of palaeo eupolyploidy or aneupolyploidy. Since no diploid with x = 8 or 9 is known in the Jurinea–Sassurea group in sensu Susanna and Garcia-Jacas (Anderberg et al. 2007; Funk et al. 2009), 2n = 34 can be justified based on two theories.

Table 2. A summary of the number of chromosome count reports (2n) for the Jurinea–Saussurea group in sensu Susanna and Garcia-Jacas (Anderberg et al. 2007) based on Watanabe (2013) and Wang et al. (2013).

Higher numbers	2n = 36	2n = 34	2n = 32	2n = 30	2n = 28	2n = 26	2n = 24	Taxon
—	2	—	—	—	—	2	—	Aucklandia*
—	8	4	—	—	—	—	—	Dolomiaea
—	1	—	—	—	—	—	—	Hemisteptia*
—	—	15	2	—	—	2	—	Hamalaiella**
1(2n = 58)	10	36	4	9	—	—	1	Jurinea
—	4	—	—	—	—	—	—	Jurinella**
—	—	—	1	—	—	—	—	Outreya**
2(38), 4(39), 1(42), 1(46), 10(48), 2(50), 28(52), 12(54), 2(64), 1(72), 1(78)	39	12	51	14	20	180	4	Saussurea

^* Synonym for Saussurea s.l.; and

^** synonym for Jurinea s.l., on the basis of Anderberg et al. (2007), Wang et al. (2007) and Funk et al. (2009).

First is the suggestion of Wang et al. (2013) who believe that the diploid number of 2n = 36 observed in Dolomiaea is a derivation from an ancestral diploid with the same number, and 2n = 34 counted in a generic complex including Jurinea and Himalaiella is generated via descending aneuploidy. They also mentioned that no polyploids based on x = 17 and 18 were found in the harsh habitats in the areas under their study. On the basis of the above interpretation and also taking into account the diploid numbers reported for the monophyletic Jurinea–Saussurea group (Funk et al. 2009) (Table 2), in order to form this complex a serial of descending and ascending aneuploidy would be required. In addition, the presence of repeated similar diploid numbers in different taxa requires us to accept several homoplasic events.

The second suggestion can be hypothesized on the basis of a kind of polyploidy pillar complex (Ehrendofer 1959) in which regardless the Jurinea’s sister groups this theory can not be explained. In this theory it is necessary to assume the presence of a complex of ancestral palaeodiploid species carrying x = 6, 7, 8, and 9 (Figure 3). Hybridization among the latter diploids, combined with a chromosomal doubling strategy to circumvent the unbalanced meioses, generated the numbers 26, 30, and 34. The diploids of 24, 28, 32 and 36 are direct consequences of auto-polyploidization. This suggestion justifies the presence of 2n = 26 in the closely related genus i. e., Saussurea without any need to a serial of aneuploidies from 36 to 26; this number is the most common in the latter taxon (Table 2).

Figure 3. Scheme illustrating a hypothetical chromosomal relationship of the Jurinea–Saussurea group in sensu Susanna and Garcia-Jacas (Anderberg et al. 2007; Funk et al. 2009). A putative ancestral palaeodiploid series is considered on the base. Through successive hybridizations, back crossings and chromosome doublings a web of reticulate evolution is generated; this implies a polyploidy pillar complex scheme (Ehrendofer 1959). In order to retain some simplicity the back crossings are not illustrated in this scheme.

This justification seems to be more rational when accepting a putative ancestral diploid core of one or a pair of basic numbers (x = 7/8) from which, via aneuploidy, other ancestral diploids were generated. Very close relationships and chromosomal affinities caused a web of reticulate evolution at tetraploid level (Figure 3), which is explicitly reflected by the reported chromosome numbers (see Table 2). This situation is marked in the relevant taxonomic treatments in which 3–19 genera (Anderberg et al. 2007; Wang et al. 2007; Funk et al. 2009) were recognized in this group. Funk et al. (2009) believed that all 16 generic segregates described within the group can be reduced into three genera: Saussurea, Jurinea and Dolomiaea.

However, as Table 2 shows, in Jurinea 34 is the most frequent diploid number in Iran and the only number reported in Turkey (Dogan et al. 2009), in the centre of its distributional range. This number can be proposed as an allotetraploid which forms the core genome in this genus. Nevertheless, there are also some other lower and higher chromosome counts, which in the frame of a reticulate evolution can be attributed to a serial of introgressive hybridizations and back crossing, at tetraploid and the lower ploidy levels. This situation has brought about a complex in which taxonomic confusions are clearly seen among the taxonomic treatments applied to this group. Based on the results of this study we accept the lumping idea of Jurinea–Saussurea group (Funk et al. 2009).

Acknowledgements

This research was supported by the Office of Graduate Studies of the University of Isfahan.