Karyotype diversity and interspecific 4C DNA variation inBupleurum
TL;DR: Investigation on karyotype, 4C nuclear DNA amount and interphase nuclear volume (INV) of different HimalayanBupleurum species belonging to Umbelliferae revealed genetic differentiation.
Abstract: Investigation on karyotype, 4C nuclear DNA amount and interphase nuclear volume (INV) of different HimalayanBupleurum species belonging toUmbelliferae revealed genetic differentiation. Numerical and structural alternation of chromosomes in interspecific level were manifested in their statistically significant altered species specific 4C nuclear DNA content. Somatic chromosome number ranged between 2n = 14 and 2n = 16.B. himalayense was reported for the first time having 2n = 16 chromosomes. Correlation coefficient among the various chromosomal and nuclear parameters showed no significant progressive or regressive interdependence except in between INV and nuclear DNA amount. Critical differences between 4C DNA content showed interspecific variation.
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TL;DR: A supplementary list of nuclear DNA C-values from 37 sources for 471 angiosperm species not listed in the aforementioned compilations, plus additional estimates for 113 species already listed by them are presented, which significantly improves representation of the global flora.
188 citations
TL;DR: Evidence from morphology, crossability, pollen viability and chromosome synapsis suggests a segmental allopolyploid origin for M. cymbalaria, a taxon of controversial taxonomic identity of the Momordica genus.
Abstract: Somatic chromosome number and detailed karyotype analysis were carried out in six Indian Momordica species viz. M. balsamina, M. charantia, M. cochinchinensis, M. dioica, M. sahyadrica and M. cymbalaria (syn. Luffa cymbalaria; a taxon of controversial taxonomic identity). The somatic chromosome number 2n = 22 was reconfirmed in monoecious species (M. balsamina and M. charantia). Out of four dioecious species, the chromosome number was reconfirmed in M. cochinchinensis (2n = 28), M. dioica (2n = 28) and M. subangulata subsp. renigera (2n = 56), while in M. sahyadrica (2n = 28) somatic chromosome number was reported for the first time. A new chromosome number of 2n = 18 was reported in M. cymbalaria against its previous reports of 2n = 16, 22. The karyotype analysis of all the species revealed significant numerical and structural variations of chromosomes. It was possible to distinguish chromosomes of M. cymbalaria from other Momordica species and also between monoecious and dioecious taxa of the genus. Morphology and crossability among the dioecious species was also studied. Evidence from morphology, crossability, pollen viability and chromosome synapsis suggests a segmental allopolyploid origin for M. subangulata subsp. renigera. The taxonomic status of the controversial taxon M. cymbalaria was also discussed using morphological, karyological and crossability data.
50 citations
TL;DR: The structural alteration of chromosomes as well as loss or addition of highly repetitive sequences in the genome showed variation in the DNA amount at cultivar level, but a marginal variation in nuclear DNA content at the cultivarlevel indicated a close relationship between them.
Abstract: Extensive karyotype analysis including determination of somatic chromosome number, total chromosome length and volume and estimation of 4C DNA amount were carried out on 9 different cultivars of ginger (Zingiber officinale Rose.) for the first time. A significant variation in nuclear DNA amount was recorded at the cultivar level. The 4C DNA amount varied from 19.663-24.102 pg in the cultivars studied. The correlation coefficient studies showed that the 4C DNA content and genomic chromosome volume were interdependent. The structural alteration of chromosomes as well as loss or addition of highly repetitive sequences in the genome showed variation in the DNA amount at cultivar level, but a marginal variation in nuclear DNA content at the cultivar level indicated a close relationship between them.
28 citations
TL;DR: By employing RAPD markers, karyotypes and 4C DNA content analysis, the present study has helped to resolve the relationship between the taxonomically diverse leguminous mangroves and study their ability to coexist with mangrove that would shed light on the evolution ofMangroves from terrestrial species.
Abstract: Randomly amplified polymorphic DNA (RAPD) markers, karyotypes and 4C DNA content were analyzed in five legume mangroves belonging to the sub-family Papilinoideae (Dalbergia spinosa, Derris heterophylla and D. indica) and Caesalpinioideae (Caesalpinia crista, Cynometra ramiflora) of the family Fabaceae to establish the genetic variability and phylogenetic affinities. Somatic chromosome numbers were reported for the first time in D. spinosa (2n = 20), C. ramiflora (2n = 26) and D. heterophylla (2n = 24) with reconfirmation of the somatic chromosome number in D. indica (2n = 22) and C. crista (2n = 24). Significant intergeneric and interspecific variation of 4C DNA content was observed and that varied from 8.970 pg in C. ramiflora to 28.730 pg in D. indica. From the RAPD analysis, the dendogram showed clustering of Caesalpinia crista and Cynomitra ramiflora into one group (81.80). In the second groups Derris indica and Derris heterophylla were more similar (83.10) than Dalbergia spinosa (85.80). Species-specific DNA markers (900 bp) obtained in D. spinosa from OPN15; 700 and 2000 bp in C. ramiflora from OPN4 and 400 and 800 bp in D. heterophylla and 500 bp DNA fragment in C. crista obtained from OPN-11 were found characteristic RAPD markers of these species. C. crista found more closer affinity to C. ramiflora of the sub-family Caesalpinioideae [genetic distance (1-F) = 0.847]. Derris indica showed closer genetic relation with D. heterophylla [genetic distance (1-F) = 0.856] than D. spinosa [genetic distance (1-F) = 0.876] where Derris and Dalbergia belongs to the sub-family Papilionoideae. By employing these markers the present study has helped to resolve the relationship between the taxonomically diverse leguminous mangroves and study their ability to coexist with mangroves that would shed light on the evolution of mangroves from terrestrial species.
20 citations
TL;DR: Random amplified polymorphic DNA (RAPD) markers are used to estimate interspecific variation among mangrove and non-mangrove Heritiera fomes, H. littoralis and H. macrophylla to find characteristic molecular markers in H. Macrophylla, a species from a non-reproductive habitat.
17 citations
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TL;DR: The average mitotic cycle duration of root meristem cells of several plants was measured with 3H-thymidine and showed that the cycle duration increases with an increase in the DNA content per cell and the average rate of DNA synthesis increased.
299 citations
TL;DR: A chronology of key events, events, and researchers’ observations that led to the establishment of the “six letters” structure of DNA in 1953 and its replacement by the four “letter T”s since then.
Abstract: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Range of Variability of DNA Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 DNA Variation in Higher Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Gymnosperms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Angiosperms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Mechanisms of Change in DNA Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Cellular and Organismic Correlations with DNA Content . . . . . . . . . . . . . . . . . . . . . . . . 40 Functions of DNA Sequences Duplicated or Deleted during Evolution . . . . . . . . . . . . . 41 Prospects for Future Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
182 citations
TL;DR: Evidence is presented which strongly supports the notion that the major evolutionary change in chromosome structure in Secale has involved the addition of heterochromatin at, or close to, the telomeres, and it is suggested that saltatory amplification events at telomere were initially responsible for each large increase in DNA amount.
Abstract: Estimates of the 4C DNA amount per nucleus in 16 taxa of the genus Secale made by Feulgen microdensitometry ranged from 28.85 picograms (pg) in S. silvestre PBI R52 to 34.58 pg in S. vavilovii UM 2D49, compared with 33.14 pg in S. cereale cv. “Petkus Spring” which was used as a standard. Giemsa C-banding patterns showed considerable interspecific and intraspecific variation and several instances of polymorphism for large telomeric C-bands. The proportion of telomeric heterochromatin in the genome ranged from about 6% in S. silvestre and S. africanum to about 12% in cultivated rye. A detailed comparison of nine taxa showed no overall relationship between 4C DNA amount and the proportion of telomeric heterochromatin in the genome. However, evidence is presented which strongly supports the notion that the major evolutionary change in chromosome structure in Secale has involved the addition of heterochromatin at, or close to, the telomeres. It is suggested that saltatory amplification events at telomeres were initially responsible for each large increase in DNA amount. Subsequently unequal crossing over between homologues may have played an important secondary role by extending the range of variation in the amount of heterochromatin at a given telomere, while crossing over between non-homologues may have provided a useful mechanism allowing an increase in the DNA amount at one telomere to be distributed between chromosomes.
145 citations
TL;DR: Whereas the last paper dealt primarily with data obtained by Mr. Bell and his associates during the course of field work in Mexico, the present one combines results obtained from both American continents and elsewhere and emphasizes Hydrocotyloideae and Saniculoideae.
Abstract: Chromosome numbers are reported for 167 collections representing 100 taxa of Umbelliferae. More than four-fifths of the counts apply to members of subfamilies Hydrocotyloideae (29) and Saniculoideae (50); the remaining 21 belong to Apioideae. Chromosome numbers of plants belonging to 68 taxa are published here for the first time; chromosome numbers are verified for 23 taxa; and chromosome numbers differing from those published previously are reported in nine instances. No chromosome counts have previously been reported for 19 of the genera included. Polyploidy has been established for Azorella, Mulinum, Coaxana, Enantiophylla, and Zozimia. THE ORIGINAL FORMAT for this series of papers reflected the view that each taxon could have its chromosome number recorded once and for all. Thus, each paper of the series was planned to include 100 hitherto unreported chromosome numbers of different taxonomic entities. It quickly became apparent that this scheme was insufficiently flexible to allow for the variation in chromosome number found to occur in many taxa and did not permit the recording of important cytological data on different geographical populations of the same taxon, some of them on different continents. The doctrine of "one taxon, one chromosome number" has proved to be a gross oversimplification! We have gradually been altering our procedure to permit presentation of numbers at variance with our own earlier reports and those of other authors, and to allow for a richer geographical sampling, particularly with regard to Latin America. We continue to report on the genus Eryngium in somewhat greater detail because of the cytological diversity revealed in this cosmopolitan group. We have not figured a chromosome count unless it appears to be new or unless it differs from one hitherto published. A voucher specimen for each report is preserved. Most of these Recelved for publication 3 February 1971. Mr. Constance wishes to express his appreciation to the National Science Foundation (Grant GB-6741), to I. N. T. A., Instituto de Botinica Agricola, Castelar, Argentina, and to The Regents, University of California, for enabling him to conduct field work in Argentina in 1967-68, and to the many Argentinian botanists who made this trip an unforgettable experience. The three earlier papers in this series (Bell and Constance, 1957, 1960, 1966) provided a rationale for our program of investigating chromosome numbers in Umbelliferae as well as a series of progress reports. The same general methods of investigation and presentation have been emp oyed in this fourth installment except that we have felt it unnecessary to illustrate all counts reported. The great majority of the counts offered here have been made by Mr. Chuang. vouchers are housed in the Herbarium of the University of California, Berkeley, with duplicates in the Herbarium of the University of North Carolina, Chapel Hill, or at Illinois State University, Normal. The vouchers for counts of Tierra del Fuegan plants, made from buds furnished by Mrs. Goodall of Ushuaia, are in her personal collection, surely the most southerly herbarium in the world. Whereas the last paper dealt primarily with data obtained by Mr. Bell and his associates during the course of field work in Mexico, the present one combines results obtained from both American continents and elsewhere and emphasizes Hydrocotyloideae and Saniculoideae. We are very grateful for the generous efforts of the many contributors listed. This particular paper has benefitted especially from the contributions of Dennis E. Breedlove, Robert W. Cruden, Rae Natalie Goodall, Antonio Krapovickas and Carmen Cristobal de Krapovickas, Reid Moran, T. Myndel Pedersen, P. Raulino Reitz, Hans Sleumer, Otto T. Solbrig, and the late Elwood Molseed. The staff of the Jardmn Botanico, Montevideo, Uruguay, has been especially generous with significant material. Through the courtesy of Paul C. Hutchison, who organized the trip and collected the material, and of Marion S. Cave, who made the counts, we are privileged to publish data obtained by the 7th University of California Botanical Garden Expedition to the Andes, 1963-64. We have, of course, freely availed ourselves of botanical garden seed lists, and express our appreciation to these rich sources of material. More than 1,250 seed samples of Umbelliferae have now been planted and grown in the University of California Botanical Garden in the past ten years. (The "Constance numbers" below 3,000 in the third column of the table were assigned to materials furnished by the senior author that were grown in the Garden.) It is
119 citations