Structure and Behavior of Chromosomes in Different Varieties of Aster Amellus L. and their mode of Origin
TL;DR: Regular bivalent formation has been noted in all of them, inspite of the occurrence of structurally altered chromosomes, and the role of structural alterations of chromosomes in the origin of the different garden forms has been suggested.
Abstract: SUMMARYDetailed cytological study has been performed on six different horticultural varieties of Aster amellus, L. All the individuals have been found to contain 2 n = 18 chromosomes.Karyotype analysis has been done in five varieties, while in one variety, « mauve », the number has been determined from the meiotic count only. On the basis of the minute karyological differences between the different varieties, the role of structural alterations of chromosomes in the origin of the different garden forms has been suggested.From the present and the previous records, the importance of aneuploidy in the evolution of the different species of Aster has also been emphasized.Meiosis has been studied in four varieties. Regular bivalent formation has been noted in all of them, inspite of the occurrence of structurally altered chromosomes. It has been explained by the fact that these varieties have attained homozygosity for changes during cultivation with the possible elimination of heterozygous forms.
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TL;DR: The results of this study show that the contact zone of diploid and hexaploid cytotypes in the Czech Republic is much more diffuse than indicated in previous records, which suggests a secondary contact zone.
Abstract: Background and Aims Polyploidy is viewed as an important mechanism of sympatric speciation, but only a few studies have documented patterns of distribution and ecology of different cytotypes in their contact zone. Aster amellus agg. (Asteraceae) is one of the species with documented multiple ploidy levels. The aim of this study was to determine spatial distribution and ecology of two cytotypes, diploid (2n = 18) and hexaploid (2n = 54), of Aster amellus agg. at their contact zone in the Czech Republic. Methods Root-tip squashes and flow cytometry were used to determine the ploidy of 2175 individuals from 87 populations. To test whether some differences in ecology between the two ploidy levels exist, in each locality
62 citations
Cites background from "Structure and Behavior of Chromosom..."
...Other published records of ploidy levels of this species mention 2n = 66, counted in a plant of unknown origin in a Botanical garden in Freiburg (Huziwara, 1962), and 2n = 66 and 2n = 76 in garden cultivars of this species (Annen, 1945; Chatterji, 1962)....
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TL;DR: It is concluded that the basic number x = 9 which is so common in Astereae and Anthemideae is perhaps of ancient polyploid origin and may have been derived ultimately from x = 5 of the ancestral stock throughpolyploidy and aneuploidal reduction.
Abstract: Cytotaxonomic observations have been made on 71 Indian taxa of the tribes Astereae, Anthemideae, Heliantheae and Helenieae (family Compositae). Cytological races have been reported in 5 species. It...
27 citations
TL;DR: This paper deals with taxonomy, morphology, distribution, habitat requirements, life cycle and biology of this species, with special emphasis on the differences between diploid and hexaploid plants, which co-occur in Central Europe.
Abstract: Aster amellus L (Asteraceae) is a polymorphic aggregate of taxa The species aggregate is distributed through Central and Eastern Europe and Western Asia The habitats of the species include grasslands, clearings, edges, slopes, waysides and open forests Typical habitats of this species have declined over the last decades, and A amellus became endangered in many parts of Central Europe This paper deals with taxonomy, morphology, distribution, habitat requirements, life cycle and biology of this species Special emphasis is given to the differences between diploid and hexaploid plants, which co-occur in Central Europe
15 citations
TL;DR: Chromosome numbers for 33 collections belonging to 28 species and 25 genera from ten different tribes are reported and polyploidy seemed to have played an important role in evolution of the taxa discussed.
Abstract: 1. Chromosome numbers for 33 collections belonging to 28 species and 25 genera from ten different tribes are reported.2. Results of cytological study in 13 species were discussed in detail, since these were either studied for the first time or gave new counts or else showed other features of cytological interest.3. Dysploidy was found to be common feature at the intraspecific level.4. Polyploidy, as well as ascending and descending dysploidy seemed to have played an important role in evolution of the taxa discussed.
14 citations
01 Jan 2004
TL;DR: Chromosome numbers are reported for the first time for 303 individuals of 112 taxa and cultivars and five hybrids from 16 genera, nearly all from eastern Canada and the eastern United States as discussed by the authors.
Abstract: Chromosome numbers are reported for the first time for 303 individuals of 112 taxa and cultivars and five hybrids from 16 genera, nearly all from eastern Canada and the eastern United States. Counts for several taxa from China, Japan, the United Kingdom and for several garden cultivars of Old World taxa are reported. Also included are seven corrections and changes of identifications for previously published reports for taxa in Solidago. The majority of the reports are for asters listed in this paper under the generic name Symphyotrichum (including Virgulus) plus species of Aster (including Asteromoea, Diplactis, and Kalimeris), Callistephus, Doellingeria, Eurybia, Galatella, Ionactis, Ocletnena, and Sericocar pus, and for goldenrods in Solidago and Euthamia. The following are first reports for the taxa: Aster pyrenaeus cv. "Lutetia", 2n = 36 + 2-4 supernumeraries, cult. Ontario; Solidago altiplanities, 2n = 18 from Texas; S. arenicola, 2n = 36 from Alabama; S. glomerata 2n = ca. 126 (14x) from North Carolina; S. speciosa subsp. pallida, 2n = 18 from South Dakota; Symphyotrichum plumosum, 2n = 8 (two populations) from Florida; and S. tradescanti, 2n = 32 from Maine. All other counts confirm previous reports for the taxa. A number of the reports are for rare taxa in Ontario: Solidago arguta, 2n = 18, first count for Ontario; Symphyotrichum praealtum var. praealtum, 2n = 32; S. prenanthoides, 2« = 32, first counts for Ontario (8 populations); and S. shortii, 2n = 16. A number of the counts are first reports for a particular taxon in a state (e.g., Solidago altissima subsp. altissima, 2n = 36 from Tennessee; S. brachyphylla, 2n = 18 from Florida; S. canadensis var. hargeri, 2n = 18 from Virginia; Symphyotrichum novae-angliae, 2n = 10 from Georgia and North Carolina; S. priceae, 2n = 64 from Georgia). Differences in the karyotypes of Old and New World species of asters are discussed.
13 citations
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TL;DR: Cytological findings, presented here, corroborate Kitamura's system of classification in most cases and Judging from their karyotypes, polyploid plants in Aster are possibly allopolyploids.
Abstract: 1. The karyotypes were analysed in twenty-three collections, belonging to seventeen species, one subspecies and five varieties of Aster.2. Cytological findings, presented here, corroborate Kitamura's system of classification in most cases.3. Judging from their karyotypes, polyploid plants in Aster are possibly allopolyploids.4. Sections of Aster have karyotypes quite characteristic of themselves.5. Heterogeneity of the genus is evidenced in the wide range in chromosome length as well as morphology.
85 citations
TL;DR: The evolution of Chromosome Structure and the Origin of Agricultural Strains in Crop Plants and its Significance in Speciation are studied.
Abstract: Introducction 514 Types of Chromosomal Change in Relation to Speciation 516 Diminution in Chromatin as an Indication of Structural Changes in Chromosomes 518 Karyotypic Changes and the Origin of Agricultural Strains in Crop Plants 520 Fragmentation of Chromosomes as a Physical Basis of Speciation 521 A Tentative Suggestion Regarding the Evolution of Chromosome Structure 524 Inconstancy in Chromosome Complements within a Tissue and its Significance in Speciation 526 Conclusion 532 Further Research 534 References 5 35
46 citations
TL;DR: The study of the chromosomes of palms has always been considered very difficult, as is clearly evidenced by the lack of data on a large number of genera.
Abstract: THE study of the chromosomes of palms has always been considered very difficult, as is clearly evidenced by the lack of data on a large number of genera1. Even where the number of chromosomes has been recorded, the details of the structure are unknown.
42 citations
24 citations
TL;DR: The emmer wheat (Triticum dicoccum Schrank) and some of its varieties are known for their resistance to black rust, and the Indian emmer or khapli is extensively used in breeding rust-resistant varieties.
Abstract: THE emmer wheat (Triticum dicoccum Schrank) and some of its varieties are known for their resistance to black rust, and the Indian emmer or khapli is extensively used in breeding rust-resistant varieties. It is usually grown in Central and Southern India and is commonly known as khapli wheat; botanically it is Triticum dicoccum Schrank var. farrum Bayle. According to Percival1, the Indian and Abyssinian emmers have had a common origin and both are allied to T. dicoccum Schrank var. ajar Percival.
11 citations