Karyotype Report
New chromosome counts in Cousinia (Asteraceae) from flora of Iran-II
2024 年 89 巻 1 号 p. 57-59
詳細
2024 年 89 巻 1 号 p. 57-59
Here, we present the chromosome numbers of four Cousinia species including C. fragilis (sect. Spinuliferae), C. gedrosiaca (sect. Lachnosphaerae), C. ghahremanii (sect. Pugioniferae), and C. inflata (sect. Cynaroideae) distributed in southeast and west parts of Iran. Our results revealed 2n=24 and x=12 for C. fragilis, C. gedrosiaca, and C. inflata and 2n=26 and x=13 for C. ghahremanii. The chromosome numbers are new to science and confirm the previous reports of the related sections.
Cousinia Cass. is one of the most dominant upland steppe genera of the Irano-Turanian floristic region (Djamali et al. 2012). The genus comprises over 700 species worldwide concentrated in the mountainous areas of Turkey, Iran, Afghanistan, and Central Asia (Knapp 1987). About 250 species of the genus are distributed throughout Iran, of which over 165 species are endemic (Rechinger 1972, 1979, Ghahreman and Attar 1999, Mehregan and Kadereit 2008, Mehregan and Assadi 2009, 2016, Assadi 2010, Attar and Djavadi 2010, Attar 2011, Rastegar et al. 2018, Attar et al. 2022).
Chromosome numbers are documented for over 50% of Cousinia species (Susanna et al. 2003, Ghaffari et al. 2006, Djavadi 2007, 2012, Djavadi and Attar 2010, Sheidai et al. 2012, Bordbar et al. 2017). Nevertheless, the chromosome number of some species of the genus is still unknown. This study aimes to determine chromosome numbers in four Cousinia species from the flora of Iran.
The karyological studies are conducted on the root meristematic cells of the following species: Cousinia fragilis C. Winkl. & Bornm., C. gedrosiaca Bornm. & Gauba, C. ghahremanii Mirtadz. & Attar, and C. inflata Boiss. & Hausskn. Sectional classification of Rechinger (1972, 1979) was followed for Cousinia. Related literature, as well as online databases (IPCN, http://legacy.tropicos.org/project/ipcn) were used to assess the previous chromosomal works on the examined taxa. Locality information and voucher specimen number of the taxa are presented below: C. fragilis C.Winkl. & Bornm., Iran: SE., Kerman Prov., NW of Jiroft, the pass between Sarbizan and Ramun, 29°03′58.8″N, 57°31′42.5″E, 3,130 m, 06.VIII.2022, Mirtadzadini and Bordbar 4301 (MIR). C. gedrosiaca Bornm. & Gauba, Iran: SE., Kerman Prov., Mt. Jebal-e Barez, the pass between Dehbakri and Saghder, Mirtadzadini 4302 (MIR). C. ghahremanii Mirtadz. & Attar, Iran: SE, Kerman Prov., Ravar to Kuhbanan, Rudkor valley, 2,700 m, 17.VI.2004, Mirtadzadini 4303 (MIR). C. inflata Boiss. & Hausskn., Iran: W., Kermanshah Prov., Kerend, near Asiab-Tanureh village, 1,880 m, 03.XI.2016, Bordbar 4304 (MIR).
Preparation of chromosome spreadsThe roots were germinated from seeds at 25°C. The actively growing root tips were pretreated with α-monobromonaphthalene for 5 h at 4°C. Afterward, the root tips were fixed with Carnoy solution (1 : 3 glacial acetic acid–absolute ethanol) for at least 24 h at 4°C, hydrolyzed in 1 M HCl at 60°C for 2 min, then washed and stained in aceto-iron hematoxylin at 30°C for 2–3 h and mounted in 45% acetic acid (Payandeh et al. 2015). Digital microphotographs from at least five well-spread metaphase plates were taken using an OPTIKA–OPTIKAM HDMI–4083.13 microscope equipped with a digital camera.
Cousinia sect. Spinuliferae Rech. f., Cousinia fragilis showed 2n=24 chromosomes (Fig. 1A). This small section comprises six species, of which four species (C. longifolia C.Winkl. & Bornm., C. sicigera C.Winkl. & Bornm., C. fragilis C.Winkl. & Bornm., and C. barezica Assadi) are distributed in central and southeast of Iran and two species (C. shahrestanica Rech.f. and C. qaisarensis Rech.f.) in Afghanistan (Rechinger 1972, 1979, Assadi 2009). Chromosome number records have been published for C. longifolia and C. sicigera (Bordbar et al. 2017). Both species revealed 2n=24. So, the basic number x=12 is consistent with the previous reports for this section.
(A) C. fragilis, (B) C. gedrosiaca, (C) C. ghahremanii, and (D) C. inflata. Scale bars=10 µm.
Sect. Lachnosphaerae Rech. f., Cousinia gedrosiaca indicated 2n=24 chromosomes (Fig. 1B). This section is represented by 12 species, out of which three species are entirely endemic to Iran and three species are common between Iran and Afghanistan. Others exist in Afghanistan (Rechinger 1972, 1979). There are only two previous chromosome counts for this section: C. lachnosphaera Bunge, 2n=24 (Podlech and Bader 1974) and C. eriobasis Bunge, 2n=24 (Djavadi 2005). This is the first chromosome count for this species and the confirmation of x=12 for this section.
Sect. Pugioniferae Bunge, C. ghahremanii showed 2n=26 chromosomes (Fig. 1C). This section is represented by 16 species (Rechinger 1972, Assadi 2009, Attar and Mirtadzadini 2009, Attar et al. 2018), out of which 14 species are distributed in Iran. Among the Iranian species 13 taxa are endemics. Its center of diversity is northwest and west of Iran. General distribution of the sect. Pugioniferae is Iran, Turkey, Transcaucasia, Syria, Iraq, and Afghanistan (Rechinger 1972).
Several chromosome counts are reported for the members of this section: the species also show 2n=26: C. calcitrapa Boiss. and C. macroptera C.A.Mey (Afzal-Rafii 1980), C. belangeri DC. (Ghaffari and Chariat-Panahi 1985), C. gracilis Boiss. and C. platyptera Bornm. & C. Winkl. (Djavadi and Attar 2010), C. macroptera C.A.Meyer, and C. wesheni Post (Uysal et al. 2022). Only for C. pugionifera Jaub. & Spach 2n=24 was reported by Aryavand (1975).
Sect. Cynaroideae Bunge., C. inflata showed 2n=24 chromosomes (Fig. 1D). This section is the largest section of the genus distributed in Iran, Iraq, Turkey, former Soviet Union, Lebanon, Syria, Afghanistan, and Pakistan (Rechinger 1972, 1979). Iran with over 80 species seems to be the center of diversity of the section (Rechinger 1972, 1979, Attar and Djavadi 2010, Rastegar et al. 2018, Attar and Amini Rad 2019).
On the basis of the previous chromosome reports (Aryavand 1975, Afzal-Rafii 1980, Tscherneva 1985, Ghaffari 1986, 1987, Ghaffari et al. 2000, 2006, Susanna et al. 2003, Djavadi and Attar 2010, Djavadi 2012), this section has only one basic chromosome number, x=12.
Cousinia has a high number of endemic species in the Irano-Turanian region. This genus was grouped in to three subgenera (Cynaroides, Hypacanthodes, and Cousinia) and 50 sections (Tscherneva 1988a, b). In this study, we investigated the chromosome numbers in four species belonging to the sect. Cynaroides, Lachnosphaerae, Pugioniferae, and Spinuliferae of the genus Cousinia. Our investigation of the chromosome numbers in C. fragilis (2n=24), C. gedrosiaca (2n=24), C. ghahremanii (2n=26), and C. inflata (2n=24) are new to science and provide confirmation of the previous reports of the related sections.
Based on the previous studies, five basic chromosome numbers, x=9, 10, 11, 12, and 13, are confirmed for Cousinia however, x=12 and x=13 are the most frequent basic chromosome numbers in this genus (Susanna et al. 2003, Ghaffari et al. 2006). Some sections have more than one basic chromosome number (e.g. sect. Pugioniferae) while others are characterized by one basic chromosome number (e.g. sect. Cynaroides, Lachnosphaerae, and Spinuliferae).
FB contributed to material preparation, data collection, and methodology. FB, RS, and FM performed lab work. The first draft of the manuscript was written by FB. MM contributed to material preparation and commented on previous versions of the manuscript.
