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G. Madhusudana Rao, V. Manmada Rao
1983 Volume 48 Issue 3 Pages
427-436
Published: September 25, 1983
Released on J-STAGE: March 19, 2009
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Two varieties of rice, namely, Tella hamsa and IR-24 were utilized to study the mutagenic efficiency, effectiveness and factor of effectiveness by physical (gamma rays) and chemical mutagens (HA, NMU and MMS) in rice. The frequency of chlorophyll mutants in M
2 generation and mutants per mutation showed similar trend in physical and chemical mutagen treated population of Tella hamsa but differed in IR-24. The frequency of chlorophyll mutations was highest in medium fertile group of gamma treatment in both the varieties. Whereas in chemical mutagen treated population, the frequency was highest in high fertile group in Tella hamsa and in medium fertile group in IR-24. Chemical mutagens were efficient in Tella hamsa while gamma treatment in IR-24. Chemical mutagens were markedly effective than physical mutagens in the production of chlorophyll mutants in both the varieties. The factor of effectiveness was uniformly hgth in gamma treatment over chemical mutagens in IR-24, whereas in Tella hamsa the chemical mutagen MMS recorded the highest followed by gamma rays.
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C. Singh, J. Olejniczak
1983 Volume 48 Issue 3 Pages
437-444
Published: September 25, 1983
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Effect of soaking in oxygenated water, gibberelic acid on azide mutagenesis and DMSO used as carrier of sodium azide were investigated in barley. Presoaking for 8-16 hours in oxygenated water enhanced mutagenic efficiency of sodium azide. In treatment when mutagen was dissolved in 0.5 to 0.75% of DMSO it appeared to be more efficient. Pretreatments with GA slightly increased M
1 spike sterility whereas post treatments reduced seedling growth injury and enhanced mutagenic efficiency.
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Suniti Kumar Mandal, Rabindra Krishna Basu
1983 Volume 48 Issue 3 Pages
445-450
Published: September 25, 1983
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Pre- and post-irradiation treatments of root mesistems of
A. cepa, C. juncea and
L. esculenta with colchicine provided considerable protection against X-rayinduced chromosomal aberrations. The magnitude of radioprotection remained more or less equal pre- and post-treatments. The reduction in aberrant cells by colchicine implied that colchicine had provided radioresistance and stimulated restitution in pre- and post-treatments respectively.
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A. Badr
1983 Volume 48 Issue 3 Pages
451-457
Published: September 25, 1983
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The cytogenetic effects of two carbetamide containing herbicides have been investigated in the roots of
Allium cepa. These herbicides are carbetamex and paradone plus. The two herbicides exerted a marked mitodepressive action on mitosis and induced a number of chromosomal aberrations. Chromosomal aberrations produced are comprised of C-metaphase, C-anaphase, chromosomal stickiness, bridges, lagging and multipolar anaphases and telophases. Both herbicides also induced the formation of multinucleated cells, micronuclei and chromatin bridges in interphase cells. In addition to these aberretions chromatin lost its staining ability or appeared as dense granules and nuclei were vacuolated. Details of aberrations are described and probable reasons for their induction are discussed. The mutagenic potentiality of the two herbicides is pointed out.
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J. L. Tarar, V. R. Dnyansagar
1983 Volume 48 Issue 3 Pages
459-465
Published: September 25, 1983
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The present paper deals with the gamma radiation and EMS induced chromosomal aberrations in
Turnera ulmifolia Linn. Mitosis was found to be quite normal in control plants. As a result of the mutagenic treatment of seeds (gamma rays and EMS), chromosomal aberrations like stickiness, fragments, precocious movement of chromosomes, mitotic bridges and non-orientation of chromosomes were induced in the root tip cells. These irregularities were more at higher exposure of gamma rays and higher EMS concentrations for longer duration. The probable causes of the production of mitotic abnormalities following seed treatment with the mutagenic agents are discussed. The paper also includes effect of the physical and chemical mutagen on the cell division in the present plant.
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P. Abhayavardhani, Y. S. R. K. Sarma
1983 Volume 48 Issue 3 Pages
467-482
Published: September 25, 1983
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Karyological investigatoins were made on 24 taxa of
Spirogyra Link and their chromosome numbers have been reported. The chromosome numbers in various taxa exhibited a wide variation ranging from n=2 in S. VRG 80 to n=92±2 in
S. nitida, the latter being the highest chromosome number recorded for any species of
Spirogyra so far.
S. minuticrassoidea is a new addition to Indian flora. A survey of the chromosome numbers in
Spirogyra Link suggests that aneuploidy or agmatoploidy has played a more significant role than euploidy in its speciation. No correlations were observed between the width of filaments and/or number of chloroplasts per cell and chromosome numbers.
From the cytotaxonomic view point
S. paradoxa and
S. azygospora come close to each other.
S. azygospora may be a mutant of
S. paradoxa having lost the ability to conjugate. The wide range of variation in the nuclear and chromosomal characters in different taxa and their significance in the cytotaxonomy of the genus have been adequately discussed in the light of present and earlier studies.
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V. R. Dnyansagar, R. S. Nadkarni
1983 Volume 48 Issue 3 Pages
483-489
Published: September 25, 1983
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Tetraploidy was induced in
Crotalaria juncea by treating seedlings with 0.5% of aqueous colchicine. The tetraploids are characterised by possessing larger, rougher leaves, longer inflorescence axis, more output of flowers, high pollen sterility and very poor seed setting. Meiosis in C
1 and C
2 plants is irregular. The clumping of chromosomes, various tyeps of chromosomal associations, presence of univalents, unequal distribution and precocious movement of chromosomes, laggards and bridges at anaphase I and II and formation of triads and pentads of microspores have been frequently observed in the PMCs. The decrease in pollen fertility has been attributed to meiotic abnormalities. There is no correlation between pollen fertility and seed setting.
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T. Govindarajan, D. Subramanian
1983 Volume 48 Issue 3 Pages
491-504
Published: September 25, 1983
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The chromosome number of 30 species belonging to 16 genera of Acanthaceae from South India has been studied. Chromosome numbers determined in the present study range from 2n=16 to 2n=60.
Chromosome numbers determined in the present study and those reported previously in the family reveal the presence of a continuous series of basic numbers between x=8 and x=34. The commonest basic number in the family is x=16. In view of the low haploid numbers n=8 observed in two genera in the present study, x=16 is presumed to have been derived from the lower x=8 by doubling. According to the present investigation, the number 8 is suggested as the ancestral basic number of the family. It appears that aneuploid changes of chromosome numbers produced the basic numbers of x=11, 13, 14, 15 and 16 in the early evolution of the family, after which polyploidy and dibasic amphidiploidy gave rise to the higher basic numbers (x=17 to 34) now found in the family.
Karyotypes in the family also show differences in absolute chromosome size indicating changes in nuclear DNA in evolution. No definite trend of either phylogenetic increase or decrease of chromosome size is indicated by the available data.
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G. Pushpa, K. M. D. Nayar, B. G. Suryanarayana Reddy, K. G. Shambuling ...
1983 Volume 48 Issue 3 Pages
505-509
Published: September 25, 1983
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Studies on meisosis and pollen fertility have been made in BC
1F
1, BC
1F
2 and BC
1F
3 generations of
Arachis. The plants in the BC
1F
1 generation were found to contain 2n=50 chromosomes and the pollen fertility was about 36 per cent. In BC
1F
2 generation, a few plants which were erect showed 2n=40 chromosomes and a pollen fertility of 92 per cent. The seeds collected from BC
1F
2 generation (2n=40) maintained the chromosome number with a further improvement in pollen fertility (98.0 per cent). A few important yield contributing characters were studied in BC
1F
3 generation. It is suggested that a vast improvement could be made with respect to some of these characters. The plants in BC
1F
3 generation also appeared to possess field resistance to
Cercospora leaf spot disease. Selection pressure is being imposed to stabilize the yield and resistance to disease.
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G. S. Sethi, Vipan Kalia, Mamata Negi
1983 Volume 48 Issue 3 Pages
511-517
Published: September 25, 1983
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A meiotic mutant, inducing the formation of coenocytes in pollen mother cells, is reported in three lines of barley, viz., (BHS 24×Mari), HBL 175 and (Liguleless×USDA 606). The mutation appears to be of induced nature in BHS 24×Mari due to irradiation with gamma rays, of spontaneous nature in HBL 175 and of induced nature due to colchicine in Liguleless×USDA 606. It is characterised by fusion of variable number of PMCs at pre-synaptic or post-synaptic stages of meiotic prophase I, resulting into the formation of plasmodial masses or polyploid nuclei on their coalescence, irregular congression and subsequent distribution of chromatin, and formation of microspores of highly variable size and shape. The present studies establish that the phenomenon of coenocytism causes tip sterility and that the frequency of fused PMCs is higher in the tip region of the spike than in the mid or base region. These studies also indicate the occurrence of such a phenomenon during megasporogenesis too, though it needs confirmation through direct observation.
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Lilium Linn
Anima Langer, A. K. Koul
1983 Volume 48 Issue 3 Pages
519-526
Published: September 25, 1983
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Karyology and nucleolar studies on four species of
Lilium namely,
L. regale,
L. thomsonianum,
L. tigrinum and
L. roseum indicate collective functioning of all nucleolus organizing regions irrespective of the nature of cells and tissue employed.
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M. Bharathi, U. R. Murty, P. B. Kirti, N. G. P. Rao
1983 Volume 48 Issue 3 Pages
527-538
Published: September 25, 1983
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Chromosome pairing at the pachytene stage of meiosis was studied in triploid hybrids involving
A. hypogaea, and
A. chacoense and
A. villosa. There was very good pairing at least in respect of 10 chromosomes. Unpaired regions and heteromorphic bivalents were observed occasionally. Chromosome pairing indicated a close relation among the 3 species.
A. hypogaea has 10 chromosomes in common with
A. chacoense and
A. villosa although the 10 chromosomes of each these species are not necessarily homologous. Evidence was obtained for the existence of structural repatterning in the A-genome species and also in the genomes of
A. hypogaea. The information obtained was utilised in the discussion of the origin of
A. hypogaea.
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A. B. Sapre, Suniti S. Barve
1983 Volume 48 Issue 3 Pages
539-541
Published: September 25, 1983
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A method of studying somatic chromosomes from the leaf sheath meristem-intercalary meristem-of some genera of tribe Maydeae (Poaceae) has been described. The procedure outlined to bring out chromosomes from leaf sheath is simple and yields well-spread clear somatic chromosome complements for karyotype studies. The technique can be extended to all grasses with equally good results and could be found useful in chromosomal screening of a population.
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U. N. Rai, Y. B. K. Chowdary
1983 Volume 48 Issue 3 Pages
543-550
Published: September 25, 1983
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In the present communication nine species belonging to eight Chlorococcalean genera and one belonging to Chlorosarcinaceae of Chlorosarcinales have been collected locally, isolated, and grown in cultures. All the algae have been subjected to karyological investigation. Their studies have shown the existence of cytological races in the genus
Ankistrodesmus. Based on the chromosome number and karyological features the cytotaxonomic aspects of the algae have been discussed. It was concluded that taxonomic treatment on the basis of cytological data is possible only when a large number of species of each genus were undertaken and studied together.
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D. R. Malaviya, R. S. Shukla
1983 Volume 48 Issue 3 Pages
551-556
Published: September 25, 1983
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A spontaneous chimaera of
Lens culinaris var. L3991 with two triploid and one hexaploid branches was cytologically investigated. The meiotic behaviour of chromosomes in pollen mother cells of both triploid and hexaploid was abnormal. Pollen fertility study revealed that in hexaploid flowers about 87% pollen grains were sterile and in triploid ones the pollen sterility was nearly 100%. Open and artificial pollination of triploid flowers indicated total female sterility. Only a single pod could be obtained from hexaploid after self-pollination. Stomatal frequency ratio per unit area on the leaves in hexaploid and triploid branches was 2.2:3.7.
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Meiotic effects of the insecticide “Dursban”
Soheir M. Amer, Odette R. Farah
1983 Volume 48 Issue 3 Pages
557-563
Published: September 25, 1983
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The meiotic effects of the insecticide 0, 0-diethyl 0-3, 5, 6-trichloro-2 pyridyl phosphorothioate “Dursban” were studied.
Vicia faba plants (V. Giza I) were sprayed with aqueous saturated “Dursban” solution for different periods of time, at the seedling and flowering stages. All the treatments induced a significant percentage of abnormal pollen mother cells (PMCs/plant). The perentage of the induced abnormalities decreased from the 1st to the 2nd meiotic division, and neither tetrads nor pollen grains were affected. The most dominant type of the observed anomalies was chromosome stickiness in the different meiotic stages. Its percentage reached more than 90% of the observed abnormal PMCs in most of the conducted treatments. Disturbed meta- and anaphase II, lagging chromosomes, chromosome fragmentation, micronuclei and anaphase bridges were observed, however, in a low percentage.
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G. Pushpa, B. G. Suryanarayana Reddy
1983 Volume 48 Issue 3 Pages
565-568
Published: September 25, 1983
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Open pollination of the triploid hybrid between
A. hypogaea×
A. duranensis produced hexaploid plants with 2n=60 chromosomes. Cytomorphological studies were made in the OP
1 and OP
2 generations.
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Sanae Kasahara, Yatiyo Yonenaga-Yassuda
1983 Volume 48 Issue 3 Pages
569-576
Published: September 25, 1983
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Cytogenetic studies were performed on 26 specimens of the rodent
Zygodontomys lasiurus (2n=34, 2n=33/34), collected in the State of São Paulo, Brazil. The G- and C-band patterns of mitotic chromosomes were studied and the NORs were localized in the karyotype. Two types of acrocentric X chromosomes, morphologically distinctive, were observed, one of them having an enlarged short arm (X
m). In some females the sex chromosome pair consisted of an X
m and a small submetacentric X
d similar to the Y chromosome. The possibilities that these are females bearing a deletion in one X plus a duplication in the other, or are true XY females are discussed. A chromosome mosaicism of 2n=33/34 type was detected in one female. The 2n=34 cell line had an X
mX constitution, while the 2n=33 cells were X
mO. Both early dissociation between X and Y chromosomes and altered segregation of such chromosomes at metaphase II were observed in one male specimen.
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P. K. Agarwal
1983 Volume 48 Issue 3 Pages
577-580
Published: September 25, 1983
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Secondary association of bivalents, in groups ranging from 2-6 was observed in PMCs of
Cissus discolor (2n=48) at diplotene and metaphase I stages. Polyploidy and hybrid nature of the species have been attributed to be the possible causes of secondary association.
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Réginald Bolduc, Luc Couture
1983 Volume 48 Issue 3 Pages
581-595
Published: September 25, 1983
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Triticum aestivum L. and
Medicago sativa L., cultivars Kharkov and Saranac respectively, were germinated in presence of different doses of fungicides. Benomyl and triadimenol did not affect the germination of winter wheat while aluminium phosphite and benomyl had non adverse effect on alfalfa. Imazalil and mephforuxam decreased the germination of both species and triadimenol affected the germination of alfalfa. Fenapanil (0, 5g a.i./kg seeds) did not affect the germination of both species. Fenapanil (0, 5g) did not affect the frost resistance (LT-50) of both species. The other fungicides decreased this LT-50. Fenapanil and imazalil (0, 5g) had no effect on the root apex cell ultrastructure of winter wheat. Benomyl (4g) induced the formation of vesicles in the nuclear membrane and in the endoplasmic reticulum. Further, the interphase nucleus chromatin displayed a flocculation pattern. The nucleolus granular zones also disappeared and only the fibrillar zones remained visible. Mephfuroxam treatment (2g) induced a strong cell plasmolysis. The nuclear membrane showed a wrinkled appearance and the chromatin adopted a dense and compacted pattern. As a result of treatments with triadimenol and aluminium ethylphosphite (2g) the fibrillar zones aggregated in the center of the nucleolus while the granular zones dispersed at the edge. Fenapanil (0, 5g) had no effect on alfalfa root apex cell ultrastructure.
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Tomosaburo Yabuno
1983 Volume 48 Issue 3 Pages
597-604
Published: September 25, 1983
Released on J-STAGE: March 19, 2009
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The West African annual diploid
E. obtusiflora (2n=2x=18) is characterized by the morphology of its spikelets and is partially self-incompatible. The result of the author's field observation in Nigeria indicated that this species is a companion weed of African rice
Oryza glaberrima. The annual tetraploid
E. oryzicola (=
E. phyllopogon Stapf subsp.
oryzicola (Vasing.) Koss., 2n=4x=36) is a companion weed of common rice
Oryza sativa, and also is the carrier of two of the three genomes of the annual hexaploid
E. crus-galli (2n=6x=54), the wild form of the Asian cultivated species
E. utilis. The self-pollinated, stoloniferous perennial species
E. stagnina is distributed in tropical Asia and Africa, and includes some cytoytpes. The F
1 hybrids of
E. oryzicola and the Thai 4x strain (2n=4x=36) of
E. stagnina with
E. obtusiflora were artificially produced. The results of the cytogenetical studies on these F
1 hybrids indicated that the genome of
E. obtusiflora may be related to one of the genomes of the Thai 4x strain and that
E. obtusflora has more or less the cytological characteristics which are requisite for a presumable diploid carrier of the third genome of
E. crus-galli.
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A. A. Al-Taweel, D. P. Fox
1983 Volume 48 Issue 3 Pages
605-620
Published: September 25, 1983
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Germ cell differentiation and kinetics were investigated in the coleopteran genus
Dermestes. Each species undergoes a fixed number of encysted spermatogonial divisions in which the cell cycle remains constant but the cell size is progressively reduced. Primary spermatocyte development is characterised by considerable growth and the variable meiotic development time is correlated both with DNA C-value and taxonomic grouping within the genus. Spermatogenesis proceeds throughout most of larval and all of pupal and adult life. Cell renewal is from a small number (2-8) of undifferentiated spermatogonia in each testis follicle which probably divide quasi-dichotomously. A male
D. maculatus produces>10
7 sperm during its lifetime.
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R. K. Somashekar, Govindappa D. Arekal
1983 Volume 48 Issue 3 Pages
621-625
Published: September 25, 1983
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It is established that heavy metal complex ions and cyanides induce chromosomal aberrations in
Allium cepa. It is concluded that these pollutants present in the electroplating waste water increase mutation rates when they are present in high concentration. Further studies on the role of individual metal ions and cyanides may throw more light on their capacity in bringing about chromosomal aberrations.
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J. Christopher
1983 Volume 48 Issue 3 Pages
627-631
Published: September 25, 1983
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The cytology of two taxa of Pontederiaceae is reported, viz.
M. vaginalis (n=26, 2n=52) and
M. vaginalis var.
plantaginea (n=12, 2n=24). The chromosome number of the latter taxon is a new count. The karyotype of
M. vaginalis consisted of three pairs of M type, 7m type, 12sm type and 4 st type with 2B type of asymmetry. In
M. vaginalis var.
plantaginea, the karyotype consisted of 2 pairs of M type, 5m type, 4sm type and one st type with 2B type of asymmetry. These two taxa show the basic numbers 13 and 6 respectively. They are morphologically almost distinct with conspicuous differences in leaf-shape and plant size. The similarity in chromosome morphology shows their colse relationship. It is suggested that
M. vaginalis is an allotetraploid of
M. vaginalis var.
plantaginea and
M. hastaefolia.
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I. The genus Habenaria Willd
S. K. Kashyap, P. N. Mehra
1983 Volume 48 Issue 3 Pages
633-646
Published: September 25, 1983
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Sixteen species of
Habenaria are studied cytologically.
H. lawii (2n=48) and
H. triflora (2n=42) are investigated for the first time. Karyotype analysis is made of 12 species. Three different size categories i.e. small, medium and large are observed in different species. Chromosomal races are seen in
H. densa (2n=44, 48) and
H. edgeworthii (2n=42, 84). It is concluded that the original basic number is x=7 and most of the species in the genus have been stabilised at the hexaploid level with n=21 chromosomes. Aneuploidy is not infrequent.
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II. Several genera
S. K. Kashyap, P. N. Mehra
1983 Volume 48 Issue 3 Pages
647-657
Published: September 25, 1983
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Chromosomal information on 12 species under 8 genera is presented. Genus
Diplomeris with a single species (
D. hirsuta: 2n=42) is investigated for the first time.
Herminium congestum (n=20) and
H. duthiei (n=20) are cytologically newly recorded species. Aneuploid number n=18 is noticed in
Herminium gramineum. Cytological races are observed in
Orchis latifolia (2n=40, 80) and
Herminium lanceum (2n=36, 76).
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John E. Dillé, Elizabeth N. King
1983 Volume 48 Issue 3 Pages
659-662
Published: September 25, 1983
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Rye root tips were exposed to different concentrations of DMSO. Mitotic indices were determined for the various treatments. As the concentration of DMSO increased from 1% to 11%, the mitotic index decreased from 20.6 to 0.6. The dosage response curve for 50% inhibition was near 3% DMSO.
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I. Superchromosomal organization in polytene nuclei of Chironomus and Mycetophila
Lucian Gavrila
1983 Volume 48 Issue 3 Pages
663-669
Published: September 25, 1983
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Our investigations on salivary polytene chromosomes of different dipteran species allowed to reach the conclusion that the superchromosomal circular organization of eukaryotic genome is a normal state at least in interphase nucleus, being implied in eukaryotic DNA replication as well as in interphase functions of genetic material.
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Norman L. Taylor, John M. Gillett, Nirmala Giri
1983 Volume 48 Issue 3 Pages
671-677
Published: September 25, 1983
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Chromosome number and morphology have differentiated in section
Chronosemium independently of general morphology or longevity. Series of x=7 and x=8 exist and the only polyploid is
T. dubium (2n=28). The yellow-green seeds of
T. aureum and
T. badium, both in the x=8 series are distinctively different from other species of the section. Including the chromsome number of
T. boissieri reported for the first time here, the total number of species of section
Chronosemium for which numbers have been determined is now 12, with a total of 192 species determined for the entire genus
Trifolium, a genus of perhaps 250 species. Care should be exercised with respect to names supplied on seed packets. It is evident that a large percentage of seed sources are either misidentified or do not employ recent nomenclature.
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V. Cytotaxonomic consideration of the tribes vernonieae and eupatorieae
P. M. Mathew, Abraham Mathew
1983 Volume 48 Issue 3 Pages
679-690
Published: September 25, 1983
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Chromosome data from PMCs and/or root tip cells in 16 species belonging to four genera (
Struchium,
Centratherum,
Vernonia,
Elephantopus) of the tribe Vernonieae, and nine species belonging to four genera (
Adenostemma,
Ageratum,
Eupatorium,
Mikania) of the tribe Eupatorieae from South India are reported. Karyomorphology was studied in most of them.
The basic chromosome constitution and their evolution in the two tribes are discussed in the light of available chromosome data. In both tribes, x=10 is considered to be the original or earlier evolved condition from which the lower ones evolved by progressive reduction, and the higher ones by polyploidy followed by reduction. The consistently less specialised karyotypes in the x=10 taxa is shown to support this. In the Eupatorieae, the x=10 condition is postulated to have originated from an ancestral n=5. The occurrence of chromosome numbers in a regular series in multiples of 5 in the type genus
Eupatorium is shown to support this.
The systematic relationships of the Vernonieae and Eupatorieae are considered. The predominant occurrence of x=10 in both the tribes is pointed out to provide cytological support for their close relationship, which in turn are most related to the Heliantheae.
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P. K. Agarwal, R. P. Roy
1983 Volume 48 Issue 3 Pages
691-697
Published: September 25, 1983
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Seeds of
Coccinia indica were X-radiated to induce breakage in the Y chromosome to scan the active regions carrying female suppressing and male promoting genes in it and to study the effect of radiations on the sex ratio in the population. Irradiated plants showed poor development of sex organs in male and female flowers. Meiosis was highly irregular characterised by the presence of univalents and multivalents. A higher frequency of females (92.03%±2.71) in the irradiated population than in nature (63.8%±4.81) indicates the great susceptibility of male plants to radiations.
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D. R. Kutarekar, K. B. Wanjari
1983 Volume 48 Issue 3 Pages
699-705
Published: September 25, 1983
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Karyotype of twelve varieties of
Cicer arietinum L. has been reported. Karyotypic differences and similarities between these varieties have been discussed.
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Yoshio Yoshida, Katsufumi Nakamura, Akio Hiura
1983 Volume 48 Issue 3 Pages
707-717
Published: September 25, 1983
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The effects of isopropyl N-(3-chlorophenyl) carbamate (CIPC) on
Vicia faba root tip cells were studied. The contraction of mitotic chromosomes was conspicuously intensified by CIPC. The susceptibility to CIPC was comparatively lower in this plant than in other reported plants regarding to a growth inhibition, and the degree of contraction of chromosomes was rather time dependent but not very significantly dose dependent. Regular formation of mitotic apparatus was blocked. Autoradiography showed the depression of RNA synthesis in nucleus.
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VIII. Male meiosis in 26 species
R. C. Verma, S. N. Raina
1983 Volume 48 Issue 3 Pages
719-733
Published: September 25, 1983
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Detailed male meiosis was studied in 26 species. Twenty three species were diploid (n=7, 8) and three were tetraploid (n=16). Various evidences show that basic number of the genus is eight.
Twenty diploid species had either 7 (
C. incana) or 8 bivalents at diakinesis or metaphase I. The occurrence of 0-4 univalnets in a few cells in
C. maxillaris and
C. mucronata has been ascribed to early separation of synapsed homo/homoelogues and/or precocious separation of rod bivalents. The presence of 0-12 univalents in
C. pallida (6.24/cell) has been attributed to asynapsis/desynapsis. Complete bivalent formation in three tetraploid species indicates their allopolyploid origin. The occurrence of non-random distribution of chiasmata in many species seems to be an important genetic factor. B chromosomes were recorded in 6 species.
Only in a few species abnormalities like late disjunction of bivalent/bivalents, lagging chromosomes, chromatin bridges with/without fragments were observed at anaphase I, II/telophase I, II.
It has been concluded that apart from gene mutations, important genetic factors like non-random distribution of chiasmata, reduced chiasma frequency, cryptic structural hybridity and paracentric inversions have played an important role in the evolution within the genus. Polyploidy has played a minor role.
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S. S. Choudhary, R. P. Roy
1983 Volume 48 Issue 3 Pages
735-740
Published: September 25, 1983
Released on J-STAGE: March 19, 2009
JOURNAL
FREE ACCESS
Altogether eight species belonging to the genera
Clerodendrum L.,
Lippia Houst. ex Linn. and
Holmskioldia Retz. of the family Verbenaceae were karyotypically studied with a view to assess their phylogenetic position and trend of speciation. The karyological studies in six species of the genus
Clerodendrum of the family Vervenaceae showed 2n=46, 48, 50 and 52. The addition or deletion of a pair of chromosome appears to have played decisive role in speciation within the genus at tetraploid level.
Diploid numbers of chromosomes are found to be 36 and 32 in
H. sanguinea and
L. nodiflora respectively. They possess symmetrical karyotypes and appear to be more primitive than
Clerodendrum.
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