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Turczcminowia 19 (3): 115-119 (2016) KÜISSN 1560~7259 (print edition)
DOI: 10.14258/tiirczaninow ia. 19.3.8 |§| TURCZ ANINOWIA
http://turczanin0wia.asu.ru »¿Ld ISSN 1560-7267 (online edition)
УДК 582.998:576.316.353.7.087(571.52)
Karyotypes of two endemic species of Asterothamnus Novopokr. (Asteraceae) from South Siberia (Tuva)
E. A. Korolyuk1, M. N. Lomonosova1, T. Eu. Aleshina2
'Central Siberian Botanical Garden, Siberian Branch of Russian Academy of Sciences, ul. Zolotodolinskaya, 101, Novosibirsk,
630090, Russia. E-mail: L_Koroljuk@ngsl.ru
2The Federal Research Center Institute of Cytology and Genetics, Prospect Lavrentyeva, 10, Novosibirsk, 630090, Russia
Key words. Asterothamnus, chromosome number, karyotype.
Summary. The karyotypes of two endemic species such as Asterothamnus heteropappoides and A. poliifolius from South Siberia were studied. Both species were diploids with the chromosome numbers of 2n = 2x = 18. The polyploidy and satellites were not found. For the first time, the chromosome morphology has been studied and the idiograms have been plotted. The chromosome sizes ranged from 6.42 to 4.23 ^m for A. heteropappoides and the karyotype formula of 8m + 1sm and that from 5.88 ^m to 3.64 ^m for A. poliifolius and featuring the karyotype formula of 9m.
Кариотипы двух эндемичных видов А81его1катпш Novopokr. (Asteraceae) из Южной Сибири (Тува)
Е. А. Королюк1, М. Н. Ломоносова1, Т. Е. Алешина2
'Центральный сибирский ботанический сад СО РАН, ул. Золотодолинская, 101, Новосибирск, 630090, Россия
2Федеральный исследовательский центр институт цитологии и генетики, пр-т Лаврентьева,
10, Новосибирск, 630090, Россия
Ключевые слова: Asterothamnus, хромосомные числа, кариотип.
Аннотация. Приведены кариотипы двух эндемичных видов Asterothamnus heteropappoides и A. poliifolius из Южной Сибири. Оба вида диплоидны с числом хромосом 2n = 2х = 18. Полиплоидии и саттелитов не обнаружено. Впервые изучена морфология хромосом для этих видов и приведены идиограммы. Размер хромосом варьирует от 6.42 цт до 4.23 цт for A. heteropappoides с формулой кариотипа 8m + 1sm и от 5.88 цт до 3.64 цт для A. poliifolius с формулой 9т.
Introduction
The genus Asterothamnus Novopokr. belongs to the subtribe Asterinae (Cass.) Dumort. (the tribe Astereae, the family Asteraceae). According to Nesom & Robinson (2007), it includes 13 genera and approximately 270 species. The molecular-phylogenetic analysis of the subtribe Asterinae (Li et al., 2012; Korolyuk et al., 2015) states
the differentiation of Asiatic taxa into five well-supported clades. These are the Galatella group with the species of Asian genera Galatella Cass. s. l. and Tripolium Nees.; the groups of species of North American origin; and three groups of allied Eurasian species: (1) the group of typical Eurasian Aster L. (2) the Heteropappus group including Heteropappus Less. and Kalimeris Cass., as well as (3) Asterothamnus group. The monophyletic
Поступило в редакцию 19.02.2016 Принято к публикации 25.08.2016
Submitted 19.02.2016 Accepted 25.08.2016
Korolyuk E. A.
Karyotypes of two endemic species of Asterothamnus Tuva
clade Asterothamnus includes endemic Central Asian species of the genera Asterothamnus and Rhinactinidia Novopokr., several endemic species of Aster from China, and the monotypical genus Arctogeron DC. All the genera mentioned, except for Asterothamnus, contain polyploid taxa. According to the published data, a number of species of the Asteraceae featuring single chromosomes in a chromosome set that may differ morphologically from each other. This can serve as an additional taxonomic marker and reflect evolutionary relations of the allied taxa (Li, 2006). The species belonging to the Asterothamnus group have been less studied cytologically: the chromosome numbers of 2n= 18, which have been reported in the two species of Asterothamnus, are known for two species of Asterothamnus (Krasnikov, Korolyuk, 1995) and those for Arctogeron gramineum (L.) DC. (Rostovtzeva, Ligus, 1978). However, the chromosome morphology has not been studied yet.
Asterothamnus includes seven xerophytic species which are restricted to semi-deserts or dry rocky steppes. Most of the species grow in the territories of Mongolia and China; two species are endemic to Middle Asia (Novopokrovskiy, 1950; Grubov, 1982; Chen et al., 2011). Two species occurring in Siberia, A. heteropappoides Novopokr. and A. poliifolius Novopokr., are endemics to Tyva Republic (Korolyuk, 1997).
The aim of this work is to study karyotypic peculiarities of chromosomes of Siberian A. heteropappoides and A. poliifolius as a part of
ongoing revision of the genera of the subtribe
Asterinae.
Materials and methods
The plants for the study were collected in the territories of Ovyursky and Tes-Khemsky Regions of the Republic of Tyva. The herbarium samples are stored at the Herbarium of the Central Siberian Botanical Garden SB RAS (NS).
The karyological analysis was made by using root meristem squash preparations from seedlings. Seeds were sprouted in petri dishes on wet sterile sand at 27 °C and light regime providing 16 hours of daylight and eight hours of darkness. The germs were treated in 0.2 % colchicine for two hours and then fixed in a mixture of ethanol-acetic acid (3:1). The chromosomes were stained with aceto-haema-toxyline according to Smirnov (1968). Slides were examined under Axioscop-40 microscope. Chromosome analyses were made on 5-10 slides under 100X magnification. The study of karyotypes and their descriptions were made according to Levan et al. (1964). A1 was estimated according to Romero Zarco (1986), and TF % followed Huziwara (1962). Chromosomes and chromosome arm lengths measurement were made by MicroMeasure software environment (Aaron Reeves, USA).
Results and discussion
Morphological peculiarities of chromosomes of two rare species of Asterothamnus from South Siberia were studied.
Fig. 1. Microphotograph of somatic metaphases: A - Asterothamnus heteropappoides (2n = 18). Scale bars: 5 ^m; B - Asterothamnus poliifolius (2n = 18). Scale bars: 10 ^m.
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Table 2
Parameters of mitotic metaphase chromosomes of Asterothamnus poliifolius
Table 1
Parameters of mitotic metaphase chromo somes of Asterothamnus heteropappoides
Chro- Total chro- Long Short Arm Centromeric Relative Centromeric position
mo- mosome arm arm ratio index size S.D
some length (C) length length R:L/S I: (S/C).I00 Mm
no ^m (L) ^m (S) ^m ^m ^m
1 6.42 3.76 2.66 1.41 41.48 14.18 medium
2 5.59 3.55 2.04 1.74 36.46 12.34 smedium
3 5.30 3.08 2.22 1.39 41.91 11.70 medium
4 5.10 2.78 2.32 1.20 45.43 11.25 medium
5 4.90 2.78 2.12 1.31 43.21 10.82 medium
6 4.68 2.63 2.05 1.29 43.76 10.34 medium
7 4.61 2.48 2.13 1.16 46.22 10.16 medium
8 4.48 2.44 2.04 1.20 45.55 9.89 medium
9 4.23 2.23 2.00 1.12 47.20 9.33 medium
A1 = 0.23
TF % = 42
Chromosome no Total chromo- Long Short Arm Centromeric Relative Centromeric
some length arm arm ratio index size position S.D
(C) jm length length R:L/S I: (S/C).I00
(L) (S) im im
jm
1 5.88 3.25 2.63 1.24 44.71 14.96 medium
2 4.75 2.70 2.05 1.32 43.12 12.09 medium
3 4.58 2.84 1.75 1.62 38.10 11.66 medium
4 4.30 2.39 1.90 1.26 44.30 10.93 medium
5 4.21 2.44 1.76 1.38 41.95 10.70 medium
6 4.09 2.24 1.85 1.21 45.26 10.40 medium
7 4.02 2.23 1.79 1.25 44.52 10.23 medium
8 3.84 2.12 1.72 1.23 44.84 9.77 medium
9 3.64 2.04 1.60 1.27 44.02 9.25 medium
A1= 0.23
TF % = 42
Asterothamnus heteropappoides Novopokr.; 2n = 2x = 18 (Fig. 1A).
Collection site: "The Republic of Tyva, Ovyur-sky Region, 3 km down the Khundurgun Pass towards Khandagaity settlement. Road-side by the Khandagaity River bank, 50°73914'N, 92°17339'E, 05 IX 2013. A. Yu. Korolyuk, E. A. Korolyuk s. n."
The karyotype consisted of nine pairs chromosomes. The centromeres of the 1st and 3-9th pairs are located at the region (m), while that of the 2nd pairs at the region (sm). Satellites were not visualized. Chromosome sizes ranged from 6.42 to 4.23 ^m. The longest arm was 3.76 ^m, the shortest arm was 2.00 ^m. Karyotype formula of the species was 2n = 8m + 1sm. (Table 1, Fig. 2A). The previously known number of chromosomes determined for the
material from Erzinsky Region of Tyva Republic was confirmed (Krasnikov, Korolyuk, 1995).
Asterothamnus poliifolius Novopokr.; 2n = 2x = 18 (Fig. 1B).
Sampling location: "The Republic of Tyva, Tes-Khemsky Region, east of Ak-Chyraa settlement. The Khoohlu River Valley, pebble alluvium, 50°70480'N, 93°34650'E, Altitude = 816 m. 05 IX 2013. A. Yu. Korolyuk, E. A. Korolyuk s. n."
The karyotype consisted of nine pairs of chromosome. Most of the centromeres were situated at the centric region (m). Satellites were not found. Chromosome sizes ranged from 5.88-3.64 ^m. The longest arm was 3.25 ^m, while the shortest one was 1.6 ^m. Karyotype formula: 9m (Fig. 2B; Table 2).
Korolyuk E. A.
Karyotypes of two endemic species of Asterothamnus Tuva
ljim
lllllllll „.lllllllll ¡¡I...... lllllllll
В
Fig. 2. Idiograms: A - of A. heteropappoides, B - of A. poliifolius.
The chromosome number previously determined for the material from O-Shynaah settlement of Tes-Khemsky Region was confirmed (Krasnikov, Korolyuk, 1995).
Conclusively, the karyotypes of the species studied were similar in chromosome number and size, as well as no satellites and secondary constrictions. Minor differences were revealed for chromosome
morphology. Thus, karyotype formula of A. heteropappoides was 2n = 18 = 8m + 1sm, while that of A. poliifolius was 9m.
Acknowledgements. The authors thanks to A. A. Krasnikov for precious advices (Common use centre of CSBG SB RAS). The work was partly supported by RFBR Grant no.13-04-00874.
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