Karyomorphological Study Research Articles

Pollen Mitosis is a Good Choice for Gametophytic Chromosome Study in Higher Plants—Investigation with <i>Allium cepa</i> L. and <i>Aloe vera</i> L.

In higher groups of plants, the somatic cells are conventionally used for karyomorphological studies, which contain a diploid (2n) set of chromosomes. Similar to diploid sporophytic cells, a chromosomal study in haploid (n) gametophytic cells is also necessary as it unfolds the karyomorphological status of germ cells. The mature male gametophytic plant body (i.e., pollen grain) is only two- or three-celled structures. This study focused on the first mitotic division in a microspore, popularly known as ‘pollen mitosis-I.’ Allium cepa L. and Aloe vera L. are two model species for karyomorphological study. Microspores of these species have been stained with 2.0% acetocarmine. The present finding reveals that the cell division in microspores of these two species is completely normal without any significant irregularities. As expected, the chromosome number of the microspores of Allium cepa is n=8 and Aloe vera is n=7, exactly half the number of their sporophytic plants. The haploid karyotype of Allium cepa is the symmetric type with karyotype formula ‘6m+2sm,’ whereas that of Aloe vera is between symmetric and asymmetric types with karyotype formula ‘3sm+4st.’ This study not only enriches the chromosomal database of gametophytes of Allium cepa and Aloe vera, but also will encourage further research on this extremely neglected topic—chromosome study in the gametophytic generation of flowering plants. As Allium cepa and Aloe vera are easily available and model species for karyomorphological study, and with two contrast karyotypes (i.e., symmetric and asymmetric), this article also helps numerous school/college teachers to teach their students about the structure and behavior of gametophytic chromosomes.

Karyomorphological study and its correlation with the quantity and quality of essential oil in Iranian chamomile accessions (Matricaria chamomilla L.)

The genetic vulnerability of crops resulting from genetic diversity depletion is one of the breeders' main concerns. Therefore, wild species play an essential role in developing gene pools and improving some of the crops' agronomic characteristics. Iran country is considered a natural habitat of chamomile. In this study, six diploid accessions and two tetraploid varieties were evaluated for karyotype characteristics and phytochemical variation. Cytogenetic studies were carried out by squash method and using digital analysis. Karyotype parameters were analyzed in a completely randomized design (CRD) factorial with five cell replicates. Phytochemical properties were evaluated at the full flowering stage. Main compounds were identified by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) analysis. Karyotype analysis of diploid (2n = 2x = 18) and tetraploid (2n = 4x = 36) chamomile (accessions, varieties) showed that the chromosomes were small, ranging from 1.87 ± 0.05 μm to 4.24 ± 0.12 μm. Based on the karyotypic formula, the genotypes had two types of chromosomes (m, sm) mostly. Karyotype parameters including symmetry and asymmetry indices were estimated. Ramhormoz and Zloty Lan genotypes were the most and the least asymmetric karyotype, respectively. According to the cluster analysis based on Ward's method, the dendrogram demonstrated three groups. The principal components analysis results showed that the first three components covered 77.7% of the data variation. The essential oil content in diploid accessions ranged from 0.36% (Taft) to 0.86% (Andimeshk), and tetraploid varieties had 0.39% and 0.48% essential oil (Budakalazi and Zloty Lan, respectively). The essential oil compounds had a high-level of variation in studied genotypes.

A karyotype study in two fish species belonging to Genus Neolissochilus found in Meghalaya, India

The karyomorphological study of two species of Mahseer belonging to the genus Neolissochilus, namely Neolissochilus hexagonolepis and N. hexastichus were carried out. The study revealed the basic chromosome number in both the Masheer species was observed to be 100. However, the karyotype formula number varied among the species. N. hexagonolepis had a diploid chromosome number of 42 metacentric (m), 20 submetacentric (sm), 8 subtelocentric (st) and 30 telocentric (t) and N. hexastichus had a karyotypic formula of 32 metacentric (m), 22 submetacentric (sm), 4 subtelocentric (st) and 42 telocentric (t). This finding removed taxonomic confusion due to the differences in the chromosome number, the morphology of the chromosomes and chromosome formula between the two fish species of the genus and helped in distinctive and unblemished identification of the two species belonging to the genus Neolissochilus from Meghalaya, though they have a morphological similarity.

A karyomorphological study on the genus Muscari Mill. growing in Kahramanmaraş (Turkey)

The karyotypes and idiograms of nine Muscari Mill. species from 21 populations distributed in Kahramanmaras province, southern Turkey, were examined: M. armeniacum Leichtlin ex Baker 2n = 18 (diploid); M. aucheri (Boiss.) Baker 2n = 18 (diploid); M. anatolicum Cowley & Ozhatay 2n = 27 (triploid); M. neglectum Guss. 2n = 18 (diploid), 36 (tetraploid), 54 (hexaploid); M. parviflorum Desf. 2n = 36 (tetraploid); M. babachii Eker & Koyuncu 2n = 18 (diploid); M. comosum Miller 2n = 18 (diploid); M. tenuiflorum Tausch 2n = 18 (diploid); and M. azureum Fenzl 2n = 18 (diploid). M. anatolicum is an endemic species to Turkey and the 2n = 27 triploid population for this species is recorded for the first time. Idiograms and karyotypes of the species were obtained by the use of Cameram software.

First detailed karyo-morphological analysis and molecular cytological study of leafy cardoon and globe artichoke, two multi-use Asteraceae crops.

Traditionally globe artichoke and leafy cardoon have been cultivated for use as vegetables but these crops are now finding multiple new roles in applications ranging from paper production to cheese preparation and biofuel use, with interest in their functional food potential. So far, their chromosome complements have been poorly investigated and a well-defined karyotype was not available. In this paper, a detailed karyo-morphological analysis and molecular cytogenetic studies were conducted on globe artichoke (Cynara cardunculus Linnaeus, 1753 var. scolymus Fiori, 1904) and leafy cardoon (Cynara cardunculus Linneaus, 1753 var. altilis De Candolle, 1838). Fluorescent In Situ Hybridization In Suspension (FISHIS) was applied to nuclei suspensions as a fast method for screening of labelling probes, before metaphase spread hybridization. Classic Fluorescent In Situ Hybridization (FISH) on slide, using repetitive telomeric and ribosomal sequences and Simple Sequence Repeats (SSRs) oligonucleotide as probes, identified homologous chromosome relationships and allowed development of molecular karyotypes for both varieties. The close phylogenetic relationship between globe artichoke and cardoon was supported by the very similar karyotypes but clear chromosomal structural variation was detected. In the light of the recent release of the globe artichoke genome sequencing, these results are relevant for future anchoring of the pseudomolecule sequence assemblies to specific chromosomes. In addition, the DNA content of the two crops has been determined by flow cytometry and a fast method for standard FISH on slide and methodological improvements for nuclei isolation are described.

Karyomorphological study of some Cretan archeophytes

Karyomorphological study of some Cretan archeophytes

Karyomorphological study and report of B chromosome in Allium griffithianum Boiss. from India

The chromosomal characteristics of Allium L. have intrigued scientists on account of variation in basic chromosome number (x) ranging from 8 to 11, occurrence of polyploidy and presence of B chromosomes. The present study provides karyotypic details Allium griffithianum and presence of B chromosome in the species, the being a first report. The root-tip mitosis in this species showed presence 16 chromosomes, but 30 % of cells also showed occurrence of an additional B chromosome. The chromosome size ranged from 8.45 μm to 18.46 μm. The B chromosome size ranged between 2.4 and 2.7 μm in the mitotic metaphase plates. The mean karyotype formula was deduced to be 4.5 M + 7.5 m + 1sm + 1st +2 m (SAT) + 1B.

Karyomorphological study on some species of Launaea in Egypt

Cass. (Asteraceae; tribe Cichorieae (Lactuceae) includes species with a variety of habits, ranging from perennial and annual herbs, to spinescent sub-shrubs, cushion-forming rosette shrubs and spinescent shrubs. Nearly it global with centers of diversity in the Mediterranean area to the north temperate climates. In Egypt, the Old World species are distributed around the Mediterranean up to the Arctic and down to the Nile through Ethiopia and East Africa to South Africa and Western Asia (Alavi 1983; Boulos 2002; Zareh 2005).

Meiotic chromosome behaviour and karyomorphology of Aloe vera (L.) Burm. f.

Aloe vera (L.) Burm. f. (the family Aloaceae) indigenous to Africa is an admired medicinal plant used as a folk medicine. Meiotic division was investigated in A. vera with a view to decipher the behavior of chromosomes during prophase I and the subsequent stages of meiosis following acetocarmine squash technique. The various meiotic stages from leptotene to pollen development were studied. Seven bivalents were clearly visible at diplotene, and the chiasma frequency averaged to 1.86 per bivalent and 13.1 per pollen mother cell (PMC). Prophase I stages are difficult to identify due to clumping of chromosome threads. Second nuclear division, however, allows clear distinction of chromosome configuration. Besides clumping, various other types of chromosomal aberrations such as stickiness and fragments at metaphase I, precocious movement of chromosomes, bridges, laggards and unequal separation of chromosomes at anaphase I and unequal separation of chromosomes at telophase II were noted. Karyomorphological study on the other hand, was carried out in anther wall (mitotic) cells of A. vera. Mitotic as well as meiotic studies in the species showed 2n=14 chromosomes including two pairs of sat-chromosomes. The karyotype of the species was adjudged to be typically asymmetric.

A karyomorphological study on two newly recorded taxa of Lycoris (Amaryllidaceae) in Anhui province, China1*

Abstract Two wild populations of L. houdyshelii and L. straminea were first discovered in Anhui province and cytologically studied. The results showed that two kinds of cytology were found in L. houdyshelii, with one having the karyotype 2n = 31=3m+13st+10t+5T, and the other having the karyotype 2n = 30=3m+21st (SAT) +3t (SAT) +3T. The karyotypes and secondary constriction are reported for the first time. The karyotype of L. straminea is formulated as 2n = 19=3m+7st+4t+5T, which is similar to some previous reports and confirmed here. The karyotypes of these two taxa are both of 3B type according to the degree of asymmetry and Stebbins’ criteria. According to the gross floral morphology, phenology and karyotype of these two taxa, it is suggested that L. houdyshelii is probably a hybrid between a taxon with 2n = 6M+10T, such as L. longtuba or L. chinensis and L. radiata var. pumila, and L. straminea putatively originates in hybridization between L. radiata var. pumila and L. chinensis.

Karyotype analysis of Santalum album L.

A karyomorphological study on Santalum album was conducted for the fi rst time. The interphase nucleus was a simple chromocenter type while the prophase chromosomes were of the interstitial type. The shoot-tip meristems of some S. album individuals were found to be mixoploid, i.e. 2n = 2x = 20 and 2n = 4x = 40. Two different karyotypes, one diploid (2n = 2x = 20) and one tetraploid (2n = 4x = 40), were also present; their karyotypic formulae were 2n = 20 = 18m + 2sm and 2n = 40 = 32m (2SAT) + 8sm, respectively. The chromosomes of both karyotypes showed centromeres predominantly in a median position and a few submedian centromeres, of 2B type, of a primitive and symmetrical nature.

Advances in chromosomal studies in Neottieae (Orchidaceae): constitutive heterochromatin, chromosomal rearrangements and speciation

Abstract — In this work, we describe a karyomorphological study on three taxa of the tribe Neottieae (Orchidaceae). Epipactis aspromontana and E. schubertiorum are characterized by a chromosome complement of 2n = 2× = 38. Significant differences in heterochromatin distribution were found between them. Similarities in the karyotype structure and C-banding of E. schubertiorum and E. helleborine group have been observed. A specimen of E. aspromontana showed a triploid chromosome number. The meiosis are characterized by univalent, bivalent and trivalent forms and in some somatic metaphase cells has been possible to observe a series of aneuploid numbers with 46, 47, 48, 49, 50, 51, 52 and 53 chromosomes. The largest differences can be emphasized between the Epipactis species and Neottia nidusavis, mainly in the the karyomorphology and heterochromatin distributions. In Neottia nidusavis the evolution process seems to be determined by reversing Robertsonian mutations.

A karyomorphological study of the generaMicheliaandManglietia(Magnoliaceae)

A karyomorphological study on eleven and one hybrid belonging to Michelia L. and Manglietia Blume (Magnoliaceae, sensu stricto) was conducted. The structure of interphase nuclei and prophase chromosomes of rep- resentatives of the two genera were presented here for the first time. Three karyomorphological types at resting nu- clei and two types of prophase chromosomes were recognized according to Tanaka's catalogue (1971; 1977; 1980) respectively. It might provide information to distinguish the intergeneric and infrageneric relationships in Magno- liaceae. An evolutionary trend is proposed that awaits verification by further study. All taxa studied have the same diploid number of chromosomes (2n=38) in somatic cells, three of them were reported for the first time, and others were comfirmed. The karyotype analysis have shown a predominance of chromosomes with centromeres in a median position and a few submedian centromeres, except for Michelia hypolampra with subterminal and terminal point cen- tromeres, which also showed high karyotypic symmetry. The karyotype data documented with 2n=38 indicate that the speciation may have taken place predominantly at the diploid level in Michelia and Manglietia and that minor structural alternation of chromosomes may have resulted in distinct morphological divergence and probably played the most important role in the evolution of genus and species.

A karyomorphological study in the monotypic genus Lamiophlomis and five species in Phlomis (Lamiaceae)

The monotypic genus Lamiophlomis (including only L. rotata) and five species of Phlomis in the Lamiaceae were karyornorphologically studied. The interphase nuclei are all categorized to be round prochromosome type, and the mitotic-prophase chromosomes are all categorized to be interstitial type. The karyotype formulae are as follows: L. rotata, 2n=2x=22=18m+4sm; R umbrosa, 2n=2x=22=22m; P ruptilis, 2n=2x=22=22m; P betonicoides, 2n=2x=22=22m; P melanantha, 2n=2x=22=22m(2sat); P strigosa, 2n=6x=66= 60m+ 6sm. The basic chromosome number of Lamiophlomis is confirmed to be x=11, the same as that of Phlomis sect. Phlomoides, which shows that Lamiophlomis rotata should be better treated as a species of Phlomis.

Cytology, palynology, and taxonomy of Asteropyrum and four other genera of Ranunculaceae

A karyomorphological study of two species in Asteropyrum (Ranunculaceae) and five in presumably related genera (one each in Caltha, Coptis, and Dichocarpum and two in Thalictrum) reveals close similarities between Asteropyrum and Caltha, but obvious differences between Asteropyrum and Coptis, Dichocarpum, and Thalictrum, in some karyological features, such as the structure of the interphase nuclei, chromosome size, basic chromosome number, and condensation behaviour of chromosomes during the mitotic prophase. The chromosomes of Asteropyrum are categorized as being of the R-type and the basic chromosome number is confirmed as x = 8, indicating a possible close affinity of Asteropyrum to members in the subfamily Helleboroideae, in particular to Caltha and its allies. Asteropyrum peltatum and Asteropyrum cavaleriei are shown to be more or less differentiated from each other in gross morphology and palynology, and somewhat independent in geographical distribution, albeit with intermediate forms occurring where their distribution zones overlap. It seems justifiable to treat them as two subspecies of A. peltatum. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152, 15–26.

A karyomorphological study of 40 species in 11 genera of the Magnoliaceae from China

In this paper, 40 species in 11 genera of the Magnoliaceae from China were karyomorphologically investigated for a better understanding of the intergeneric relationships in the family and the systematic positions of some species, particularly those in the genus Manglietia. The 20 Manglietia species studied are all diploid with 2n=38, indicating that in this genus the speciation may have taken place predominantly at the diploid level and that minor structural changes of chromosomes may have resulted in distinct morphological divergence. In the genus Magnolia, cytotypes with various ploidy levels from 2x to 6x have been found, which may be, at least to some degree, associated with the wide distributional range and complex gross-morphological variation of the genus. Our results indicate that Manglietia should be an independent genus from Magnolia and do not support the treatment of merging them as a genus. All the Michelia species already with chromosome numbers are diploid with 2n=38, while most of the species in Magnolia subgen. Yulania are polyploid, suggesting that Michelia is not closely allied with Yulania and that the two groups should not be merged as a genus. All Parakmeria members are polyploid. It is noteworthy that cytological evidence is generally less informative in clarifying the intergeneric relationships of the Magnoliaceae than the interspecific relationships within a given genus of the family because reticulate evolution may have extensively occurred in this family. Systematic positions of some species in Manglietia are discussed based on evidence from cytology, morphology and geographical distribution.

Karyomorphology of Heptacodium (Caprifoliaceae s.str.) and its phylogenetic implications

AbstractA karyomorphological study of the species Heptacodium miconioides and five species in Caprifoliaceae of presumably related genera [Abelia and Depelta (Linnaeeae); Lycesteria and Lonicera (Caprifolieae); Weigela (Diervilleae)] reveals similarities in some karyological features such as structure of interphase nuclei, chromosome size, and condensation behaviour of chromosomes during mitotic prophase. However, differences between them in chromosome base number and morphology of metaphase chromosomes have also been revealed. The chromosome number of Heptacodium 2n = 28 is unique in Caprifoliaceae, presumably having resulted from polyploidization following hybridization between two ancestral species (possibly with chromosome base number x = 8 or 9) bearing characters of tribes Caprifolieae and Linnaeeae, respectively. The phylogenetic position of Heptacodium is discussed based on combination of karyomorphology and previous morphological and molecular data.

Karyomorphological study of the Spiraea japonica complex (Rosaceae)

Reported in this paper is a karyomorphological study on one natural population of each of eight varieties in the Spiraea japonica complex. The interphase and mitotic prophase can be classified into the simple chromocenter type and the proximal type, respectively. The metaphase karyotypes of the eight varieties were formulated as follows: S. japonica van japonica: 2n = 18 = 14m + 2sm + 2st; S. japonica var. acuta: 2n = 18 1m + 4sm + 3st; S. japonica var. incisa: 2n = 18 = 12m + 4sm + 2st; S. japonica var. stellaris: 2n = 18 = 15m + Ism + 2st; S. japonica var. acuminata: 2n = 18 = 14m + 2sm + 2st; S. japonica var. ovalifolia: 2n = 18 = 10m + 2sm + 2st + 4t; S. japonica var. glabra: 2n = 18 = 10m + 4sm + 4st; S. japonica var. fortunei: 2n = 36 = 17m + 16sm + 3st. Karyomorphological study reveals that the chromosome numbers within the complex are stable, and that karyomorphological divergence between the varieties lies mainly in chromosome size and organization. Based on the karyomorphological data and geographical distribution of the complex, the differentiation pattern as well as evolutionary mechanism of the complex is evaluated.

Karyomorphological studies onWoodwardia sensu lato of Japan

Karyomorphological comparisons were made of five species of JapaneseWoodwardia. There were no marked differences at interphase and prophase among the five species.Woodwardia japonica, W. prolifera, andW. unigemmata were diploid with 2n=68 and the formulas of their metaphase karyotypes uniformly 4m(median centromeric chromosomes)+12sm(submedian)+52(st+t)(subterminal and terminal).Woodwardia orientalis was tetraploid with 2n=136 and 8m+24sm+104(st+t), and the ratio of each chromosomal type to total complement was identical to that of three diploid species. These four species had several characteristics in common:x=34, the longest chromosome of sm, and a mean chromosome length over 3.0 μm. AlthoughWoodwardia orientalis showed some similarity toW. prolifera, it seems to be an allotetraploid which originated by chromosome doubling of a hybrid ofW. prolifera and a diploid species as yet karyomorphologically unknown.Woodwardia kempii was tetraploid with 2n=124 and 8m+24sm+92(st+t), and differed from the others in havingx=31, the longest chromosomes of t, and a mean chromosome length under 3.0 μm. This species has been classified as an independent genus,Chieniopteris, and our karyomorphological study supports this treatment.

Karyotypes in cultivated and wild species of Linum.

Detailed karyomorphological study of 19 species and 27 collections of Linum is made. The study reveals the presence of n=8, 9, 10, 13, 14, 15, 16, 17, 18 and 30 chromosome numbers within the genus. However, the number n=9 and n=15 predominate over other numbers. L. pubescens is studied and karyotype of 13 species is described for the first time. New chromosome numbers are reported for 6 species. On the basis of general morphology and karyotype a phyletic tree is drawn to show the line of evolution within the genus and interrelationship among the species. The basic chromosome number is interpreted as x=9.