The Japanese common wheat cultivar Shirodaruma, a descendant from the landrace Daruma, is the ancestor of the donor of the semidwarfing genes, Norin 10. Breakpoints of translocations and translocated chromosomes were identified in Shirodaruma and Daruma, respectively. An amphihaploid plant containing telosome 4BS and the translocated chromosome 6B was isolated from the progeny of the cross; Shirodaruma/Chinese Spring ditelosomic 4BS//rye cv. At the first metaphase of this plant, the telosome 4BS was paired with the long arm of chromosome 6B forming a heteromorphic bivalent in 70.0% of the pollen mother cells. This indicates that the reciprocal translocation in Shirodaruma involved 4BS and 6BL. Southern hybridization of digested DNA from the isolated amphihaploid plant with probes having RFLP markers Xglk 661d and the centromere on 4BS and between Xglk 582 and 736 on 6BL, thus, gave rise to translocation chromosomes T4BL ·4BS : 6BL and T6BS ·6BL : 4BS. On the other hand, the isolated amphihaploid plant showed significantly high frequency of meiotic pairing between homoeologous chromosomes that was probably atributed to inhibition or imbalance in the normal Ph system of wheat. Telosomics and chromosomal banding analyses indicated that Daruma has translocation chromosomes T3AS ·7AS and T3AL ·7AL. Thus, Shirodaruma and ancestor Daruma carry different chromosomal translocations. This suggests that either the translocation in Daruma was restructured and a new one between 4B and 6B was formed in Shirodaruma or it is likely that the existing stock of Daruma and Shirodaruma were selected from an old landrace Daruma that was heterogeneous for both of these translocations.
In structural heterozygotes for the T3-6 chromosomal interchange in pearl millet, the percent pollen fertility correlated with percent seed set. The duplicate-deficient (dp/df) microspores degenerated at binucleate stage. The effect of the dp/df condition on the structure and function of the female gametophyte was investigated in this interchange heterozygote. Inflorescences from the interchange heterozygote plants were fixed at five developmental stages : -at pre pollination (i.e. stage 1) and post pollination (i.e. stages 2 to 5) at 24 hr intervals up to 96 hr after pollination (hap). The embryo sac (female gametophyte) was dissected from the ovule and stained with 2% acetocarmine. In the post pollination samples the rate of early seed development was estimated by counting the number of cells in the embryo and endosperm. A normal looking embryo sac was found in all the ovules at pre pollination stage. Post pollination, two kinds of abnormalities were found in 50% of the ovules : some had unfertilized embryo sacs; some showed a lag in development of the embryo and endosperm. These abnormalities could be due to the dp/df condition of the embryo sacs-the two kinds representing the two types of dp/df products formed in the interchange heterozygote. The difference in tolerance of the dp/df condition on the male and female sides is attributed to a) the (programmed) difference in the control of gametophyte development in the two sexes, and b) the existence of competition among the (three) microspore categories (normal, dp/df of one kind and dp/df of another kind) as opposed to the non-competitive aspect of megaspore development (which ever is the category)
Karyotype studies including chromosome length, chromosome volume and cytophotometric estimation of nuclear DNA amount were carried out in 8 ginger (Zingiber officinale Rosc.) cultivars. Significant variations in the nuclear DNA amount were recorded at cultivar level. The correlation coefficient studies revealed that the 4C DNA content and genome volume were positively correlated. Structural alterations in the chromosomes without the changes in the numeric chromosome number (2n=22) as well as loss or addition of highly repetitive sequences in the genome caused variations in the DNA amount at cultivar level. Marginal variations in the genome size indicated a close relationship between the cultivars.
A plant was isolated from the progeny of a cross between a translocation heterozygote mother and disomic pollen donor which carried an additional chromosome (2x+ 1) in all cells of the root tip and sporogenous tissue. The chromosome was unlike any in the standard chromosome complement. The nature and synaptic behaviour of this chromosome suggest that the aneuploid is a tertiary trisomic. The posible mode of origin of the extra chromosome and the aneuploid plant have been discussed.
The present paper presents the chromosome numbers of five brazilian species of diplopods : Plusioporus setiger (2n=10 and 2n=10+ 1B, the distinction of the sexual pair was not possible), Pseudonannolene ophiulus (2n=12, XY), Pseudonannolene halophila (2n=16, XY), Rhinocricus sp. (2n=28, XY) and Rhinocricus padbergi (2n=20, the distinction of the sexual pair was not possible).
The chromosome complements of eight species of Egyptian birds are investigated. The diploid chromosome numbers of these species, Hirundo daurica, Turdus migratorius, Corvus splendens, Bubulcus ibis, Ardeola grayii, Meleagris gallopavo, Upupa epops and Columba oenas, 74, 58, 78, 60, 60, 58, 110 and 76 are respectively. The sex chromosome constitutions are of homogametic ZZ in males and of heterogametic ZW in females. Karyotypic and morphometric data for the chromosome complements of these species have also been studied.
In this study, 1C nuclear DNA content of Pinus koraiensis collected from different sample areas was reported. Mean 1C nuclear DNA content of this species was 24.60 pg. Plants with higher 1C nuclear DNA content distributed in southern, southwestern and northeastern slopes and tableland, those with lower 1C nuclear DNA content in western slope and mountain spur. Climatic factors may be important factors related to genome size of Pinus koraiensis.
A. palustris Krapov., W. C. Gregory et Valls and A. praecox Krapov., W. C. Gregory et Valls, wild annual relatives of the cultivated peanut, belong to sect. Arachis. These species have qualities which deserve being incorporated into the cultivated peanut. Karyotypes were analysed, being for both species 2n=2x=18= 16m+ 2sm. The chromosome number of A. praecox is reported for the first time. Both species can be distinguished by a combination of parameters : karyotype formula, chromosome length, type and position of SAT chromosome, size of satellite and asymmetry indices. Knowledge about the chromosome number and karyotypes of both species is of great value for the improvement of cultivated peanut. The basic number x = 9 may have derived from ancestral x = 10 probably by aneuploidy. This fact supports the hypothesis that section Arachis is the one which presents the most advanced traits within the genus.
Zea mays ssp. mays cv. Colorado Klein organogenic calli were initiated from 11 daysold embryos on basic medium containing 2.25 μM 2, 4-D. The callus originated from one of the embryos was subcultured every month to fresh medium supplemented with 4.5 or 9 μM 2, 4-D, for 84months. The first chromosomal abnormalities appeared after 17 months of culture : 70% of regenerated plants were normal, 20% aneuploid and the remaining 10% were tetraploid. Thereafter chromosomal aberrations increased. Most (95%) of the plants regenerated after 32 months had one extra chromosome, and meiotic analysis of regenerants showed deficiencies, duplications, inversions, translocations and ring chromosomes. Chromosome number of cells from 60 months old callus ranged from 2n=18 to 2n=23, but 90% of regenerated plants had 2n=21 and the remaining 10% had 2n=20. Plants regenerated from 64 to 84 months old callus were sterile. Also, phenotypic alterations were observed in plants regenerated from 32 months and older calli. Although original maize plants are yellow flint, 75% of R0 ears showed white flint kernels and their progeny exhibited yellow flint, white flint, white dent and white sugary caryopses.
Karyotypes and meiotic chromosome pairing were studied in natural autotriploid and autotetraploid Tradescantia pallida. At both ploidy levels chromosomes appeared as metacentrics, being larger at the triploid than at the tetraploidy level (9.6-15.3 μm and 7.5-10.0 μm, respectively).T. pallida exhibits polymorphism with respect to number and position of secondary constrictions. The tetraploid had three large satellites and a small-spheric one. While the triploid had two large satellites and one small-spheric. Both the triploid and tetraploid showed reduced multivalent pairing for triploid, only one trivalent was seen in 32.8% PMC's while 67.2% PMC's had 6 bivalents plus 6 univalents. In the tetraploid, bivalent pairing was very predominant, 87.72% PMC's had 12 bivalents. The presence of a bivalent-forming system in these polyploids, most probably a genetic one, is suggested.
The Drosera chromosomes studied were not localized-centromeric but diffused-centromeric. Among the Drosera taxa studied, only D. filiformis (2n=20) had 20 weak CMA-negative orDAPI-positive large bands more than 2.97 μm2 area each at the same site of 20 chromosomes. Thus, its hybrid with D. intermedia (=Drosera × hybrida, 2n=20) had ten CMA weakly-negative orDAPI-positive bands more than 3.00 μm2 each in the same site of ten chromosomes which could be of the gamete of D. filiformis. Drosera petiolaris (2n=14) displayed the meiotic chromosome configuration of six circular bivalents with four distinct chromatids held each other with end-to-end association and two univalents at metaphase I, while D. rotundifolia (2n=20) displayed ten ring-shaped bivalents, that were quite similar to the bivalents of the localized-centromeric chromosomes. These differences in CMA-positive and DAPI-negative bands, IBAS-area, and meiotic chromosome behavior might be correlated with chromosome differentiation and speciation in the species of Drosera of the Northern and the Southern Hemispheres.
Cytological analysis were done in microsporogenesis of Boehmeria nivea (ramie) var.'Miyasaki' which was treated with 0.1+0.1% colchicine solution in seed and seedling phases. Control plants without any treatment in seed and seedling phases were also analyzed. Meiosis was normal except for the occurrence of cytomixis in both control and treated plants. Colchicine did not cause cytomixis occurrence. It was supposed that this phenomenon would be associated with crop culture condition. Although colchicine treatment was not effective to induce chromosome duplication, it may have caused reduction in average of chiasma number per cell and also reduction in pollen grain germination. Two types of pollen with different cytoplasm content were noticed in treated and in control plants. One type had full cytoplasm and other type had less cytoplasm which in many cases was wrinckled. It was supposed that this latter pollen type was consequence of cytomixis. Only full pollen grains germinated in agar media. Test for apomixis in 'Miyasaki' variety showed it did not form apomictic fruits, either in control or in 0.1+0.1% treated plants.
Although Crinum pratense and C. defixum have similar karyomorphology i.e. 2n=22 chromosomes, diffuse type of interphase nuclei and continuous type of prophase chromosomes when stained with orcein, yet a major variation, such as two CMA-positive bands in C. pratense and one in C. defixum at mataphase were found. The CMA-positive bands in both the species were found in in-terphase and as well as prophase. The GC-rich repetitive sequences seemed to keep their domain in-tact throughout the cell cycle. During counter staining with DAPI, the CMA-positive portions showed DAPI-negative bands. Reversible banding indicated that the amount of GC-rich bases was more abundant in the former species. Moreover, DAPI-positive bands appeared at the centromeric regions of 18 out of 22 chromosomes in C. pratense which were totally absent in C. defixum. It showed the AT-rich nature of C. pratense chromosome complements. Two species had different isozyme activity. Activities of esterase and acid phosphatase were higher in C. defixum. Thus the two species showed distinct variations in their fluorescent karyotypes and activities of isozymes. These features support their different species rank.
1) During a chromosomal survey of the tettigonids an unusual specimen No. 207 (in our list of specimens) was discovered which is tentatively placed under the genus Euhexacentrus of the subfam : Listroscelinae. 2) Euhexacentrus sp. (specimen No. 207) is unusual among the tettigonids as its karyotype has the lowest chromosome number of 2n=9 (8A+X) with 4 pairs of metacentric autosomes and a smaller acrocentric X chromosome. 3) This karyotype is compared with the karyotype of E. annulicornis, whose chromosome number is 12 (10A+XY) and are all metacentric. 4) The karyotype details of all the known species of the subfam : Listroscelinae are presented for comparison along with the present Euhexacentrus sp. 5) The probable evolution of the present karyotype is discussed.
This study was carried out to present cytogenetical information on the natural hybrid, 2x R.×hiraseanus, and the artificial hybrids between R. coreanus and R. parvifolius. 2x R.×hiraseanus and artificial hybrids had similar karyotypes, formulated as 2n= 14 = 10m+2sm+2tst. The formation of seven bivalents at M I in almost all PMCs of hybrids indicates that R. coreanus and R. parvifolius are closely related species with similar genomes.