Infraspecific polyploidy and gynodioecism in Ptilotus obovatus (Amaranthaceae)

1976 ◽  
Vol 24 (2) ◽  
pp. 237 ◽  
Author(s):  
D.A. Stewart ◽  
BA Barlow
Keyword(s):  
Chromosome Number ◽  
Sex Ratio ◽  
Dynamic Equilibrium ◽  
Arid Zone ◽  
Basic Number ◽  
Basic Chromosome Number ◽  
Genetic Effects ◽  
Basic Chromosome ◽  
Species Area ◽  
Selective Effects

A basic chromosome number of x = 27 is constant in 14 species of Ptilotus examined. This basic number may be polyploid in derivation, with the entire genus having developed at a stabilized hexaploid level from an ancestral stock with x = 9. Only one species, P. obovatus (Gaud.) F. Muell., shows cytotypic variation, with diploid and tetraploid forms having n = 27 and n = 54 respectively. The tetraploid biotype is relatively uniform morphologically and is distributed throughout the species area studied. Diploid biotypes are more variable morphologically and of more local occurrence, and may be isolated relicts. The adaptive tetraploid biotype has probably been a more successful recolonizer of the arid zone following Recent arid maxima. Gynodioecism is of general occurrence in both diploid and tetraploid races of P. obovatus, and is probably effective as an outcrossing mechanism in this self-compatible species. The sex ratio varies between populations, and may be in dynamic equilibrium with the genetic effects of polyploidy and the selective effects of habitat stability.

CYTOGEOGRAPHY AND EVOLUTION OF THE DESGHAMPSIA CAESPITOSA COMPLEX

1963 ◽  
Vol 41 (5) ◽  
pp. 719-742 ◽  
Author(s):  
Shoichi Kawano
Keyword(s):  
Chromosome Number ◽  
Geographical Distribution ◽  
Morphological Variation ◽  
Phylogenetic Relationships ◽  
Basic Number ◽  
Basic Chromosome Number ◽  
Basic Form ◽  
Basic Chromosome ◽  
High Chromosome Number ◽  
Deschampsia Caespitosa

The chromosome number, karyotype, and morphological variation of plants of the Deschampsia caespitosa complex are reported in this paper. It is shown that the chromosome number of 2n = 26 is most common in typical D. caespitosa (L.) Beauv. But, remembering the basic chromosome number in the Agrostideae, the original basic number of the genus Deschampsia is considered to be x = 7. Thus, a reduction of the chromosome number from 28 to 26 is speculated in this particular group of Deschampsia. The plant from Mt. Albert, Canada, referable to D. caespitosa ssp. littoralis (Reut.) Rchb., has a high chromosome number of 2n = 49. Considering the morphological affinity between D. caespitosa ssp. littoralis and D. alpina Roem. & Schult., as well as their geographical distribution, parallel development of the plants with such high irregular chromosome number is assumed.The karyotype of D. caespitosa s. str. was also investigated. This species has a highly specialized asymmetrical karyotype, viz., K(2n) = 26 = 4 V + 10 J + 12 I.On the basis of cytology, morphology, ecology, and geographical distribution, the phylogenetic relationships within this complex were considered. The littoralis type, having well-developed panicles, large spikelets, three (rarely four) florets, and a preference for wet terrestrial sites, is speculated to be the most basic form in the D. caespitosa complex, even though the type with smaller spikelets, i.e., caespitosa s. str. is at the present time much more abundant. Various other population groups such as D. caespitosa v. parviflora (Thuill.) Coss. & Germ., D. brevifolia R. Br., D. alpina Roem. & Schult., and the species of the bottnica group (including D. beringensis Hultén, D. bottnica (Wahlenb.) Trin., D. congestiformis Booth, D. holciformis F. & C. Presl, D. mackenzieana Raup, D. macrothyrsa Tatewaki et Ohwi, D. obensis Roshev., and D. wibeliana Schur.) are presumed to be more specialized.

scholarly journals The chromosome constitution of the pomoideæ

1931 ◽  
Vol 108 (758) ◽  
pp. 423-446 ◽  
Keyword(s):  
Chromosome Number ◽  
Chromosome Pairing ◽  
Chromosome Numbers ◽  
Previous Investigation ◽  
Basic Number ◽  
Basic Chromosome Number ◽  
Chromosome Constitution ◽  
Basic Chromosome ◽  
Original Ancestor ◽  
Derived Series

Previous investigation on cultivated varieties of apples have shown that the apparent basic chromosome number is 17, but chromosome pairing, morphology and breeding results indicate that the 34 chromosome form a more complex constitution than that of an ordinary diploid. In a recent paper (Darlington and Moffett, 1930) it was concluded that in the cultivated apples the set of 34 chromosome in the diploid belong to seven types, three of which are represented six times and four them are represented four times. Thus the original ancestor of the apple would have had a basic number of 7, and the present number of 17 is a secondary basic number. The derived series of polyploids with chromosome numbers 34, 51 and 68 are, therefore, secondary polyploids.

scholarly journals Malpighiaceae: correlations between habit, fruit type and basic chromosome number

2003 ◽  
Vol 17 (2) ◽  
pp. 171-178 ◽  
Author(s):  
Ricardo A. Lombello ◽  
Eliana R. Forni-Martins
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Basic Number ◽  
Basic Chromosome Number ◽  
Basic Chromosome ◽  
Monophyletic Origin ◽  
The Family ◽  
Number Variation ◽  
Family Based ◽  
The Relationship

The family Malpighiaceae presents species with different habits, fruit types and cytological characters. Climbers are considered the most derived habit, followed, respectively, by the shrubby and arboreal ones. The present study examines the relationship between basic chromosome numbers and the derivation of climbing habit and fruit types in Malpighiaceae. A comparison of all the chromosome number reports for Malpighiaceae showed a predominance of chromosome numbers based on x=5 or 10 in the genera of sub-family Malpighioideae, mainly represented by climbers with winged fruits, whereas non-climbing species with non-winged fruits, which predominate in sub-family Byrsonimoideae, had counts based on x=6, which is considered the less derived basic number for the family. Based on such data, confirmed by statistic assays, and on the monophyletic origin of this family, we admit the hypothesis that morphological derivation of habit and fruit is correlated with chromosome basic number variation in the family Malpighiaceae.

scholarly journals In vitro propagation and cytological analysis of Sophora mollis Royle: an endangered medicinal shrub

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Aakriti Bhandari ◽  
Harminder Singh ◽  
Amber Srivastava ◽  
Puneet Kumar ◽  
G. S. Panwar ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Average Length ◽  
Germplasm Conservation ◽  
Basic Chromosome Number ◽  
Shoot Tip ◽  
Ex Situ ◽  
Ms Medium ◽  
Basic Chromosome ◽  
Shoot Tip Explants

Abstract Background Sophora mollis Royle (family Fabaceae, subfamily-Papilionaceae) is a multipurpose legume distributed in plains and foothills of the North-West Himalaya to Nepal and is facing high risk of extinction due to habitat loss and exploitation by the local people for its fuel and fodder values. Therefore, the present study was conducted to standardize a micropropagation protocol for Sophora mollis by using shoot tip explants and to study the meiotic chromosome count in the species. Results Multiple shoots were induced in shoot tip explants of Sophora mollis in Murashige and Skoog medium supplemented with different concentrations of cytokinins alone (BAP, TDZ, and Kinetin) and in combination with varying concentrations of NAA. MS medium supplemented with BAP (8.9 μM) was observed to be the optimal medium for multiple shoot induction and maximum 25.32 shoots per explant was obtained with average length of 4.5 ± 0.8 cm. In vitro developed shoots were transferred onto rooting media supplemented with different concentrations of auxin (IAA, IBA, and NAA). Maximum 86% rooting was observed in half-strength MS medium supplemented with 21.20 μM NAA with an average of 21.26 roots per culture. In vitro raised plantlets were adapted to greenhouse for better acclimatization and 60% plants were successfully transferred to the open environment. Based on the chromosome counts available from the literature and the current study, the species tend to show a basic chromosome number of x = 9. Conclusion The micropropagation protocol standardized can be helpful for the ex situ mass multiplication and germplasm conservation of the endangered species. Moreover, the ex situ conservation approach will be helpful in actively bridging the gap between ex situ and in situ approaches through the reintroduction of species in the wild. The cytological studies revealed the basic chromosome number x = 9 of the species.

scholarly journals Relations and evolution in Cheilanthes (Sinopteridaceae, Pteridophita) in Macaronesia and Mediterranean area, deduced from genome analysis of their hybrids

1983 ◽  
Vol 8 ◽  
pp. 101-126 ◽  
Author(s):  
G. Vida ◽  
A. Major ◽  
T. Reichstein
Keyword(s):  
Chromosome Number ◽  
Genome Analysis ◽  
Chromosome Doubling ◽  
Diploid Species ◽  
Mediterranean Area ◽  
Basic Chromosome Number ◽  
The Other ◽  
Experimental Conditions ◽  
Natural Group ◽  
Basic Chromosome

Nine species of "Cheilantoid ferns" are known to grow in Macaronesia and the Mediterranean basin. Two of them (lacking a pseudo-indusium and having the basic chromosome number X = 29), both aggregate species which we prefer to retain in Notholaena, are not included in this study. The other seven species (with distinct pseudo-indusium and the basic chromosome number X = 30), which we accept as members of the genus Cheilanthes Sw. sensu stricto, were subjected to detailed genome analysis of their natural and experimentally produced hybrids and shown to represent an aggregate of four very distinct ancestral diploids and three allotetraploids. The latter must have once been formed by chromosome doubling in the three diploid hybrids of C. maderensis Lowe with the other three diploid species. Theoretically three more allotetraploids would be possible but their formation has obviously been prevented by the geographical separation of the three respective diploids. The most widely distributed of the tetraploids, i.e. C. pteridioides (Reich.) C.Chr. has also been resynthesized from its ancestors (still sympatric) under experimental conditions. The intermediate morphology of the allotetraploids (as compared with their diploid ancestors) is obviously the reason why their status and existence has so long escaped recognition in Europe. These seven species form a natural group and, in our opinion, should not be divided into sections.

Meiotic chromosome behaviour in Cenchrus ciliaris

Bothalia ◽  
1998 ◽  
Vol 28 (1) ◽  
pp. 83-90 ◽  
Author(s):  
N. C. Visser ◽  
J. J. Spies
Keyword(s):  
Chromosome Number ◽  
Meiotic Chromosome ◽  
Basic Chromosome Number ◽  
Chromosome Behaviour ◽  
Meiotic Abnormalities ◽  
Single Specimen ◽  
Cenchrus Ciliaris ◽  
Basic Chromosome ◽  
Single Genome ◽  
Meiotic Irregularities

A basic chromosome number of x = 9 has been confirmed for Cenchrus ciliaris L. Polyploidy is common and levels vary from tetraploid to hexaploid. Aneuploidv is reported for a single specimen, where two chromosomes of a single genome were lost. Various meiotic irregularities were observed. The highest incidence of meiotic abnormalities was observed in the pentaploid specimens. This was attributed to their uneven polyploid level All specimens varied from segmental alloploid to alloploid.

Chromosome studies on African plants. 9. Chromosome numbers in Ehrharta (Poaceae: Ehrharteae)

Bothalia ◽  
1989 ◽  
Vol 19 (1) ◽  
pp. 125-132 ◽  
Author(s):  
J. J. Spies ◽  
E. J. L. Saayman ◽  
S. P. Voges ◽  
G. Davidse
Keyword(s):  
Chromosome Number ◽  
Ploidy Level ◽  
Chromosome Numbers ◽  
Basic Chromosome Number ◽  
B Chromosomes ◽  
Basic Chromosome ◽  
Cytogenetic Studies ◽  
African Plants ◽  
First Time

Cytogenetic studies of 53 specimens of 14 species of the genus  Ehrharta Thunb. confirmed a basic chromosome number of 12 for the genus. Chromosome numbers for 13 species are described for the first time. The highest ploidy level yet observed in the genus (2n = lOx = 120) is reported for E. villosa var.  villosa. B chromosomes were observed in several specimens of four different species.

Chromosome studies on African plants. 11. The tribe Andropogoneae (Poaceae: Panicoideae)

Bothalia ◽  
1994 ◽  
Vol 24 (2) ◽  
pp. 241-246 ◽  
Author(s):  
J. J. Spies ◽  
T. H. Troskie ◽  
E. Van der Vyver ◽  
S. M. C Van Wyk
Keyword(s):  
Chromosome Number ◽  
Basic Chromosome Number ◽  
Basic Chromosome ◽  
African Plants

Representative specimens of various species of the genera  Andropogon L.,  Cymbopogon Spreng.,  Elionurus Kunth ex Willd.,  Hyparrhenia Foum. and  Hyperthelia Clayton were cytogenetically studied. All specimens had a secondary basic chromosome number of ten. Polyploidy, either as alloploidy or segmental alloploidy. was frequent. The taxa studied represent mature polyploid complexes.  

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