Cyto-genetical investigations in some common cucurbits, with special reference to fragmentation of chromosomes as a physical basis of speciation.
TL;DR: Are sex chromosomes in higher pl,~nt~ nucleologenic?
Abstract: Introduction . M~t~rial and methods 0 bservations: Cucumis a~giz,u~ . Cucumis Memo Trichoaanth~ diolca Luffa aegyp~i~c,a . Luffa a~u~an~u~a . 6'o~iuia indica Beuincasa cerifera M~,mrdica cllarantia Cucurbita ~r~aarima Polysomaty Discussion (i) Numerica! correlation between m a~m um number ofnucleoli, sat~llltes and secondary constrictions (ii) Maximum number of nucleo]i ,lnd nucleolar constrictions of chromosomes witah reference to polyplcidy and aneuploidy . . . {iii) Variation of chromosome number in Cucm.bitaceac and R~. cytogsnetic interpretation (iv} Are sex chromosomes in higher pl,~nt~ nucleologenic? . Summary P, efsrsnces P A G ~
Citations
More filters
TL;DR: Combined evidence from previously published studies and data presented herein lend support to the hypothesis that C. hystrix is either a progenitor species of C. sativus or that they at least share a common ancestral lineage.
Abstract: To investigate phylogenetic relationships in the genus Cucumis, 9 consensus chloroplast simple sequence repeat (ccSSR) primer pairs (ccSSR3, 9, 11, 13, 14, 17, 20, 21, and 23) were employed for DNA...
79 citations
Cites background from "Cyto-genetical investigations in so..."
...Two contrasting hypotheses regarding the origin of C. s. var. sativus and C. melo have been proffered: fragmentation of x = 7 to form x = 12 (Bhaduri and Bose 1947) and fusion of x = 12 to form x = 7 (Trivedi and Roy 1970)....
[...]
TL;DR: The analysis showed that satellite DNA sequences are the most dominant components in the cucumber genome using whole-genome shotgun reads and a karyotype showing the position and fluorescence intensity of several tandem repeat sequences is constructed.
Abstract: We analyzed repeat sequences composition in the genome of cucumber inbred line 9930 using whole-genome shotgun reads. The analysis showed that satellite DNA sequences are the most dominant components in the cucumber genome. The distribution pattern of several tandem repeat sequences (Type I/II, Type III and Type IV) on cucumber chromosomes was visualized using fluorescence in situ hybridization (FISH). The FISH signals of the Type III and 45S rDNA provide useful cytogenetic markers, whose position and fluorescence intensity allow for easy identification of all somatic metaphase chromosomes. A karyotype showing the position and fluorescence intensity of several tandem repeat sequences is constructed. The establishment of this FISH-based karyotype has created the basis for the integration of molecular, genetic and cytogenetic maps in Cucumis sativus and for the ultimate genome sequencing project as well.
70 citations
Cites background from "Cyto-genetical investigations in so..."
...Ayyangar (1967) found five pairs of chromosomes with nucleolar organizer regions, Bhaduri and Bose (1947) and Chen et al. (1999) found four pairs, while Ramachandran and Seshadri (1986) and Koo et al. (2002, 2005) described three pairs of nucleolar organizers in the somatic chromosome as well as in…...
[...]
20 Jul 2010
TL;DR: This review focuses on the origin and domestication, nutritional uses and medicinal properties of bitter gourd (Momordica charantia).
Abstract: This review focuses on the origin and domestication, nutritional uses and medicinal properties of bitter gourd (Momordica charantia). The botanical (taxonomy and morphology and reproductive biology), horticultural (climate and soil, culture, sex expression and modification, harvest, seed production and pests and diseases) and breeding aspects (genetic variation and germplasm development, inheritance, character association, goals and cultivar development, breeding methods and biotechnology) of bitter gourd are also discussed.
68 citations
TL;DR: Comparative mapping conducted herein supported the hypothesis that cucumber chromosomes may be the result of chromosome fusion from a 24-chromosome progenitor species.
Abstract: Cucumber, Cucumis sativus L (2n = 2 × = 14) and melon, C melo L (2n = 2 × = 24) are two important vegetable species in the genus Cucumis (family Cucurbitaceae) Both species have an Asian origin that diverged approximately nine million years ago Cucumber is believed to have evolved from melon through chromosome fusion, but the details of this process are largely unknown In this study, comparative genetic mapping between cucumber and melon was conducted to examine syntenic relationships of their chromosomes Using two melon mapping populations, 154 and 127 cucumber SSR markers were added onto previously reported F2- and RIL-based genetic maps, respectively A consensus melon linkage map was developed through map integration, which contained 401 co-dominant markers in 12 linkage groups including 199 markers derived from the cucumber genome Syntenic relationships between melon and cucumber chromosomes were inferred based on associations between markers on the consensus melon map and cucumber draft genome scaffolds It was determined that cucumber Chromosome 7 was syntenic to melon Chromosome I Cucumber Chromosomes 2 and 6 each contained genomic regions that were syntenic with melon chromosomes III+V+XI and III+VIII+XI, respectively Likewise, cucumber Chromosomes 1, 3, 4, and 5 each was syntenic with genomic regions of two melon chromosomes previously designated as II+XII, IV+VI, VII+VIII, and IX+X, respectively However, the marker orders in several syntenic blocks on these consensus linkage maps were not co-linear suggesting that more complicated structural changes beyond simple chromosome fusion events have occurred during the evolution of cucumber Comparative mapping conducted herein supported the hypothesis that cucumber chromosomes may be the result of chromosome fusion from a 24-chromosome progenitor species Except for a possible inversion, cucumber Chromosome 7 has largely remained intact in the past nine million years since its divergence from melon Meanwhile, many structural changes may have occurred during the evolution of the remaining six cucumber chromosomes Further characterization of the genomic nature of Cucumis species closely related to cucumber and melon might provide a better understanding of the evolutionary history leading to modern cucumber
68 citations
TL;DR: Autosome/Y divergence in the tropical Cucurbitaceae Coccinia grandis is document and a review of plants with heteromorphic sex chromosomes reveal no relationship between species age and degree of sex chromosome dimorphism.
Abstract: The independent evolution of heteromorphic sex chromosomes in 19 species from 4 families of flowering plants permits studying X/Y divergence after the initial recombination suppression. Here, we document autosome/Y divergence in the tropical Cucurbitaceae Coccinia grandis, which is ca. 3 myr old. Karyotyping and C-value measurements show that the C. grandis Y chromosome has twice the size of any of the other chromosomes, with a male/female C-value difference of 0.094 pg or 10% of the total genome. FISH staining revealed 5S and 45S rDNA sites on autosomes but not on the Y chromosome, making it unlikely that rDNA contributed to the elongation of the Y chromosome; recent end-to-end fusion also seems unlikely given the lack of interstitial telomeric signals. GISH with different concentrations of female blocking DNA detected a possible pseudo-autosomal region on the Y chromosome, and C-banding suggests that the entire Y chromosome in C. grandis is heterochromatic. During meiosis, there is an end-to-end connection between the X and the Y chromosome, but the X does not otherwise differ from the remaining chromosomes. These findings and a review of plants with heteromorphic sex chromosomes reveal no relationship between species age and degree of sex chromosome dimorphism. Its relatively small genome size (0.943 pg/2C in males), large Y chromosome, and phylogenetic proximity to the fully sequenced Cucumis sativus make C. grandis a promising model to study sex chromosome evolution.
65 citations
Cites background or result from "Cyto-genetical investigations in so..."
...Classic cytogenetic work established that the Y chromosome in this species is much larger than the other chromosomes [Kumar and Deodikar, 1940; Bhaduri and Bose, 1947; Chakravorti, 1948; Kumar and Vishveshwaraiah, 1952], and experimental work in the 1970s confirmed the sex-determining role of the…...
[...]
...At least one of the chromosome pairs of C. grandis labeled with 45S rDNA bears a secondary constriction, but in contrast to previous reports [Bhaduri and Bose, 1947; Agarwal and Roy, 1984; Chattopadhyay and Sharma, 1991] no secondary constriction was seen on the Y chromosome....
[...]
...As previously reported, the chromosome number of C. grandis is 2n = 22 + XX or 22 + XY [Kumar and Deodikar, 1940 probably by mistake reported 2n = 26 for both sexes; Bhaduri and Bose, 1947; Chakravorti, 1948; Kumar and Vishveshwaraiah, 1952]....
[...]
References
More filters
TL;DR: The nucleolus is organized in the telophase through the activity of a distinct deep-staining body having a definite position in one chromosome (the satellited chromosome) of the monoploid complement through a reciprocal translocation which broke this body into two parts.
Abstract: 1.
The nucleolus is organized in the telophase through the activity of a distinct deep-staining body having a definite position in one chromosome (the satellited chromosome) of the monoploid complement. Correlated with the number of satellited chromosomes present, the telophases of somatic tissue of haploids show one nucleolus, diploids, two nucleoli and triploids, three nucleoli. That the nucleolus develops through the activity of this body (refered to as the nucleolar-organizing body or element) was obtained from a reciprocal translocation which broke this body into two parts. Both interchanged chromosomes possessed a section. Nucleoli developed from each of these two segments. Thus, plants homozygous for the interchange developed four nucleoli in their somatic telophases; plants heterozygous for the interchange developed three nucleoli in their somatic telophases. Similarly, the telophase nucleoli resulting from the first division within the monoploid microspore of normal diploids show only one nucleolus, whereas, those of plants homozygous for the interchange are characterized by the development of two nucleoli.
2.
The functional capacity to develop a nucleolus is not the same for both segments of the severed nucleolar-organizing body. This is evident when the two interchanged chromosomes are present in the same nucleus. The segment of the nucleolar-organizing body possessed by one interchanged chromosome produced a large nucleolus, whereas, the segment of the nucleolar-organizing body possessed by the other interchanged chromosome produced a small nucleolus. When this latter chromosome, with the nucleolar-organizing element of slower rate of functional capacity is present without the former (i. e. without a competing nucleolarorganizing element) it produces, in contrast, a large nucleolus.
3.
The activity of the nucleolar-organizing element is hindered by certain genomic deficiencies. When this occurs, many small nucleolarlike bodies are produced and remain associated with the other chromosomes of the complement. These small nucleoli appear to develop from a swelling and later collection into droplets of the matrix substance of the chromosome.
589 citations
TL;DR: The physiological meaning of the nucleoli still remains one of the most obscure questions of the cytology as discussed by the authors, even after more than 100 years of the discovery of the Nukleolus.
Abstract: I. Einleitung. ,,Die physiologische Bedeutung des Nukleolus ist noch v611ig unbekannt, auch entbehren die bisher in Betreff derselben aufgestellten Hypothesen der genfigenden Begrfindung.\" So schreibt ZAC~ARIAS im Jahre 1885, und nicht weniger als 27 Jahre sp~ter liest man bei LCNDEGARD~ (1912): ,,l~berhaupt fehlt es nicht an Ansichten fiber die Bedeutung der Nukleolen, w~hrend die wirklich ermittelten Tatsachen ziemlich spRrlich u n d . . , auch zumeist recht unsicher sind.\" Nach weiteren 13 Jahren ist kein Fortschrit t zu verzeiehnen: ,,The physiological meaning of the nucleoli still remains one of the most obscure questions of the cytology\" (WILsO~ 1925). An Bemiihungen hat es nicht gemangelt. Das ist verst~ndlich, fehlt doch keinem tierisehen und keinem pflanzlichen Zellkern (yon ganz vereinzelten Ausnahmen abgesehen) dieser merkwfirdige K6rper. Doch bis heute sind wir fiber ,,Ansichten\" nicht hinausgekommen. Auch in der vorliegenden Arbeit wird man keine L6sung finden, im Gegenteil: Ieh habe mich bemfiht, die Frage nach der Bedeutung des Nukleolus fiberhaupt nicht aufzuwerfen. Denn es scheint, dab wir hierfiber gerade deshalb so wenig wissen, weil wir zuviel danach fragen. In wie vielen Arbeiten fiber den Kernk6rper wird die Richtigkeit des rein Ph~nomenologischen getriibt dadurch, dal3 die Frage nach der Bedeutung aufgeworfen wird. Und wieviel rein ph~nomenologisch noch unbekannt war, soll die vorliegende Untersuchung zeigen. Sie geht aus von kausaler Fragestellung. Nur mit Tatsachen wird die Antwort gegeben. Von diesen Tatsaehen aus wird man vielleicht einmal etwas fiber die Bedeutung der Nukleolen ermitteln k6nnen.
254 citations
141 citations
TL;DR: The chromosomes of the male plants of 17 genera, 22 species and 2 varieties of dioecious phanerogams have been investigated and the following 13 forms show each an unequal pair of chromosomes in addition to autosome pairs at the meiotic division in microsporocytes.
Abstract: 1. The chromosomes of the male plants of 17 genera, 22 species and 2 varieties of dioecious phanerogams have been investigated. Of these the following 13 forms show each an unequal pair of chromosomes in addition to autosome pairs at the meiotic division in microsporocytes. This unequal pair of chromosomes is assumed to be a sex chromosome complex of an XY-type. Consequently in these forms the male plants are heterogametic with respect to sex. The 13 forms are Salix leucopithecia, S. sachalinensis, S. japonica, S. melanostachys, S. gracilistyla, S. viminalis var. yezonensis Morus bombycis, Cannabis sativa, Datisca cannabina, Daphniphyllum macropodum, Trichosanthes japonica, Hydrilla verlicillata and Trachycarpus excelsus.2. In Cudrania triloba, Acer negundo, Trachycarpus excelsus, var. Fortunei and Ginkgo biloba, one unequal pair-like pair is found at the first meiotic metaphase in microsporocytes; but it is not safe to take this for a true unequal pair of chromosomes until a further examination has been made.3. One large chromosome pair in Morus and Trachycarpus often divides in two unequal parts at the first meiotic division. The signifi-cance of this particular behaviour, especially in relation to sex determi-nation, is not yet known.4. Although many suitable figures of metaphase and anaphase of the first and second meiotic divisions in the male of Spinacia oleracea have been examined, no evidence of the existence of sex chromosomes has been obtained. An examination of the female has still to be undertaken.In microsporocytes of Aucuba japonica, 16 chromosomes are found at the first meiotic anaphase. The zygotic numbers of chromosomes in both sexes are the same, being 32. No evidence as to the sex chromo-somes could be obtained in the male plant.5. All Salix plants studied, except one form of S. sachalinensis, have 19 as the gametic chromosome number which is a basis in Salicaceae. The meiotic division is quite normal in them.One form of S. sachalinensis from Hokkaidoo has ca. 24 chromosomes at the first meiotic metaphase and their behaviour in the meiotic stages is irregular.6. Humulus japonicus, growing wild in the vicinity of Tokyo, has a tripartite chromosome in addition to 7 autosomic gemini at the first meiotic division in microsporocytes. At the first meiotic metaphase, the tripartite chromosome divides in such a way that the two end chromosomes go to the one pole, while the middle one goes to the other. Its behaviour is strikingly similar to that of Rumex acetosa. As a result, with respect to chromosomes, two kinds of pollen grains maybe formed. These results confirm that attained by KIHARA.7. Humulus lupulus has 10 gametic and 20 zygotic chromosomes. In the first meiotic division of microsporocytes, 16 chromosomes of the 20 form 8 gemini in all, while the 4 remaining chromosomes do not form gemini, but are connected end to end to form a beaded string. This tetrapartite chromosome can be identified in several stages from early diaphase, in the first meiotic division. At metaphase each alternate chromosome of the tetrapartite goes to opposite poles respectively. Thus the daughter nuclei receive an equal number of chromosomes, i.e. 10 respectively. The two middle members of a tetrapartite chromosome are equal in size and larger than the two end ones which differ in size from each other. As a result, two kinds of gametes may be formed, one having a larger amount of chromatin volume than the other. The tetrapartite chromosome may be a sex chromosome complex in H. lupulus, a new type of sex chromosome.8. At metaphase of the first meiotic division in the microsporocytes of Xanthoxylum piperitum, 35 chromosomes are counted, one of which is not only the largest
104 citations
TL;DR: The misdivision and the origin of the iso-chromosome are each likely to be important as affecting the genetic structure of the chromosome and the mechanical properties of the centromere.
Abstract: Following misdivision of the centromere at meiosis in diploid and triploidFritillaria new telocentric chromosomes are formed whose broken ends rejoin within the centromere. This type of chromosome is delayed at metaphase and anaphase in the pollen-grain mitosis. It may then, either break again at the centromere, or pass without separation to the pole as a new iso-chromosome.
98 citations