Extensive karyological analysis including determination of somatic chromosome number, total chromosome length and volume and estimation of 4C DNA amount were carried out on 8 different varieties of Coriandrum sativum L. A significant variation in nuclear DNA amount was recorded in the varietal level. The structural alteration of chromosome as well as loss or addition of highly repetitive sequences in the genome have played a vital role in intervarietal DNA variation. The absence of wide differences in nuclear DNA content in the varietal level indicate a close relationship between them.
The haploid number of chromosomes in S. hjertingii Hawkes is found to be 24 (n=24) and is therefore tetraploid. The average chiasma frequencies per bivalent at diplotene and diakinesis were 1.69 and 1.27 respectively. The incidence of quadrivalents in the tetraploid species investigated is high (80.00%) indicating that they are autotetraploid with a high degree of affinity between four sets of chromosomes. The percentage of univalents is low (2.50%). Its occurrence in tetraploid may be due to genetic dissimilarity of individual chromosomes or mechanical interference with pairing due to presence of four sets of homologous chromosomes. Their behaviours cause unequal distribution of chromosomes in second metaphase plates. Univelents and fragments which failed to be included in the daughter nuclei formed micronuclei (2.86 %). The frequency of chromatid bridge is 3.83%. There is no relationship between the chromatid bridge and deformity of pollen in S. hjertingii. The strong homology between the four sets of chromosomes indicates an autopolyploid origin. This shows that polyploidy plays a major role in their evolution.
The cytological effects of two benzoylphenylurea namely XRD 473 and IKI 7899 on mitotic cells of V. faba afd H. vulgare were studied. Both agents caused a depression in mitotic index of V. faba after seed soak and root treatments. Cytological irregularities like chromosome stickiness, laggards, bridges, multipolar cells, unequal chromosomes separation, chromosomal breaks, gaps, ring chromosome, and multinucleated cells were observed in V. faba and H. vulgare. XRD 473 induced a higher frequencies of breakage and reunion type abberations than IKI 7899. A maximum of 7.62% aberrant cells were noticed after root treatment with IKI 7899 in V. faba against 8.0% after root treatment with XRD 473 in H. vulgare. The frequency of abberant cells tend to increase by increasing the concentration of the used agents.
With the objective of determining the apparent isoelectric point (pI) of the protein bodies of Glycine max in situ both before and after germination, seeds imbibed for 0 and 3 days were stained with methylene blue (MB) or xylene cyanol (XC) at various pH values (from 2.2 to 7.8), followed by cytophotometric measurements at λ=600 nm (MB) and λ=630 nm (XC). The results showed similar values for the protein material of cotyledon cells far from the vessels (pI=4.4±1), a progressive decrease in pI of the proteins located within the embryo after germination and pI=4.2±1 in the radicular parenchymatous cells, suggesting that for the mobilization of the reserve material there is an increase in the acidic groups of the protein bodies, which return to their initial quantity on reaching the interior of the growing cells.
Meiosis was studied in twelve species of Pennisetum covering three basic chromosome numbers viz. x=7, 8 and 9. Except P. americanum, P. violaceum and P. hohenackeri all others were found to be polyploids. The auto- or allopolyploid nature of these species was discussed basing on the meiotic behaviour of the cytotypes examined. It is inferred that P. mezianum, P. divisum and P. orientale are autotetraploids while P. setaceum is an allotriploid, P. purpureum and P. clandestinum tetraploids, P. villosum an allopentaploid and P. squamulatum and P. polystachion allohexaploids. The possible causes for the stabilization of these species suggested.
The effects of three IGRs (namely, CME 134, SIR 8514 and Dowco 439) on meiotic behaviour and band patterns of zein proteins in maize were studied. Cytological examinations showed that the used IGRs are effective in inducing several meiotic irregularities in the treated maize plants such as chromosome stickiness, univalents, laggards, multiploar cells, unequal chromosomes separation, bridges and tetrads with micronuclei or microcytes. The percentage of abnormal cells tended to diminish from the 1st meiotic division (7.44%-21.33%) to the second meiotic division (4.68%-12.70%) and dropped to its lowest value (1.49%-2.48%) at the tetrad stage. Analysis of zein proteins, the major storage proteins of maize endosperm, by SDS-polyacrylamide gel electrophoresis showed no detectable effect of the used IGRs on the band patterns of zein proteins as compared to the control.
The cytology of Solanum jasminoides var. grandiforum has been investigated. The root tip cells showed 10 homologous pairs and two heteromorphic pairs of chromosomes. The pollen mother cells showed one or two rings or chains of four chromosomes, indicating segmental interchanges in the taxon. The heteromorphism in two pairs of chromosomes is shown to be the result of one of the two interchanges. Various abnormalities such as chromosome lesions, asynapsis, chromosome breakages in prophase and chromatin bridges at anaphase stages were also observed in the PMCs. Only about 20% of the pollen grains were stainable. The plant was completely sterile without fruit set. The cause of abnormalities in chromosome behaviour in S. jasminoides is not clearly known. The irregularities in meiosis found in the taxon are attributed to the two interchanges and consequent changes in the location of controlling sequence which effects related genes controlling meiotic events in a co-ordinate fashion.
Cytological studies have been carried out on four different species of Agave, distributed in different parts of India. They revealed triploid to hexaploid numbers ranging from 2n=90 to 180. A distinct bimodal karyotype with very long and very short chromosomes in a definite proportion of 5:25 ratio and a constant base number of n=30 chromosomes are the most significant characteristics. However, structural alterations, principally involving the nucleolar chromosomes of both long and short types, have been recorded. Clear absence of distinct multiples in the karyotypes rules out the absence of autopolypoloidy. Total chromosome length and volume do not necessarily represent direct multiplication along with the multiplication of the chromosome number. All these factors suggest the role of structural alterations along with differential degrees of coiling of chromosomes and allopolyploidy rather than autopolyploidy in the evolution of the different taxa.
The developments of anthocyanoplasts which appeared in the cells of the first layer of cortex were observed using the hypocotyls of radish (Raphanus sativus L.) seedlings. 1. The results obtained from the fresh materials sectioned by a razor are as follows: The numbers of anthocyanoplasts per cell were reduced but their diameters increased as the hypocotyls' age. Through continuous observations on fresh materials, the fusions of two anthocyanoplasts were noted. After fusion, the volume of an anthocyanoplast was very close to the sum of those of two bodies before fusion. 2. In the fixed materials with 10% neutral buffered formalin and stained with methyl blue, fused anthocyanoplasts were also recognized. 3. From these results it is evident that fusions of anthocyanoplasts take place in the principal process in their growth.
The chromosome pairing in F1 hybrid synthesized from morphologically dissimilar species of Solanum lucani F. Muell. and S. melongena L., at metaphase I, was very irregular. The hybrid exhibited significantly low level of bivalents (5.72) and this coupled with high frequency of unpaired chromosomes (7.29) was indicative of less genetic similarity between the parents. Majority of the chromosome associations in hybrid were asymmetrical chain, spoon or V-shaped, tri-, quadri- and multivalents. About 66.67% cells have 2-3 trivalents which indicates that 5 pairs of chromosomes are involved in bringing about three interchanges and that both the parental species have heterozygosity between them for reciprocal translocation in hybrid. During first anaphase 21.56 % cells suffered from 1-3 chromatid bridges with 10.0% acentric fragments (0-2) which gave further indications of heterozygosity between the parents. Lagging, elimination or unequal separation of chromosomes generally formed micronuclei to affect pollen and plant fertility significantly. Present observations are suggestive of the species evolving from different genetic stocks.
Plants were regenerated from callus derived from stem explants of Ruscus hypophyllum L. The regenerating callus could be maintained by subculturing to basal medium containing BAP (0.5mg/l) for over five years. Detailed analysis of mitotic and meiotic chromosomes and phenotypes of regenerants for a period of three years revealed no significant differences between cultured and non-cultured plants. The preliminary evidences indicate that genetic stability is maintained in this species generated from compact callus which provides with a source of rapid multiplication.
The cells of T-enriched population did not respond to low dose of Con A, whereas low dose of Con A could induce proliferation of the cells of mixed population. The response of the cells of T-enriched population was reconstituted by PMA or purified IL-2 which was added at the time of Con A addition. IL-2 could promote IL-2R expression and proliferation of the cells stimulated with non-mitogenic dose of Con A. These results indicate that IL-2 in cooperation with low dose of Con A can activate the cells, and induce both IL-2R expression and proliferation.
Inbreds with different ploidy level allow for the study of ploidy-genotype effects on various agronomic, morphological and physiological characteristics. Isogenic diploid (2n=14)-tetraploid (2n=28) pearl millet (Pennisetum glaucum (L.) R. Br.) inbred lines Tift 23BE, Tift 239DB and Tift 23R (red plant) grown at two planting dates were evaluated in replicated tests for polyploidy effects on several morphological characteristics and leaf pigment contents. Tetraploid inbred lines 23BE and 239DB flowered later, were shorter and produced smaller panicles with less seed, but showed small or non-significant differences in length and width, and one hundred seed weight. However, tetraploid inbred 23R averaged significantly higher than the diploid in all characteristics except number of days to flowering and seed weight per panicle. Chlorophyll a and b were in similar concentrations among diploid and tetraploid inbreds, except for tetraploid inbred 238E which had higher chlorophyll a concentration. Carotene and anthocyanin concentrations increased by 300% and 100%, respectively, from the diploid to the tetraploid level in inbred 23R. The data indicated that changes in morphological characteristics were due to ploidy, plant genotype, and/or environmental conditions. A 26 May planting date with increasing day lengths was more effective for distinguishing ploidy effects than a 30 June planting date with decreasing day lengths.
Cytomorphological studies were conducted in three intergeneric hybrids, Citrus jambhiri×Poncirus trifoliata, C. reshni×P. trifoliata and (C. paradisi×C. reticulata)×P. trifoliata. The hybrids had various morphological characters intermediate to parents. Trifoliate leaf character was found to be dominant. Meiotic studies showed formation of nine bivalents and equal distribution of chromosomes at anaphase I and II in majority of PMCs indicating thereby the close homology between the genomes of two genera. Low pollen fertility was observed in C. jambhiri×P. trifoliata hybrid, whereas the reciprocal cross had high pollen fertility, indicating cytoplasmic nature of its inheritance.
The karyomorphological studies of four species of Anemone were carried out. A. obtusiloba and A. elongata have shown the chromosome consitution 2n=14 while A. vitifolia and A. rivularis 2n=16. On the basis of karyotypic analysis it was pointed out that the structural change in chromosome is one of the basic factor that controls speciation within the genus.
This paper deals with cytomorphological studies in Urginea indica Kunth. (2n=20) and U. coromandeliana (Roxb.) Hook. f. (2n=40). It has been revealed from the present investigation that U. coromandeliana is not an exact multiplication of chromosomes of U. indica, but segmental polyploid of hybrid origin. The geographical isolation, ecological factors, chromosomal repattering, hybridization and ploidy level seem to be responsible for morphological diversity in U. coromandeliana and support Hooker's (1892) recognition as a separate species. Experimental interspecific hybridization in Urginea species indicated the close interrelationship between U. indica, U. polyantha, U. govindappae and U. coromandeliana, and ‘Weak’ incompatibility reaction between U. indica and U. razii, U. coromandeliana and U. razii and distant relationship of U. congesta with other species of Urginea under investigation.
Five wild populations belonging to three species of Rauwolfza viz., R. serpentina, R. vomitoria and R. canescens have been studied for their chromosome constitution, nuclear DNA and reserpine content. Populations of R. serpentina and R. vomitoria showed diploid chromosome number i. e. 2n=22 while R. canescens showed 2n=66 chromosomes. The diploid populations were distinguishable on the basis of chromosome size and number of nucleolar chromosomes. Reserpine content varies at the intra- and interspecific levels of Rauwolfia. Highest and lowest amounts were recorded in the diploid species R. serpentina population I and in hexaploid R. canescens, respectively. In R. serpentina the highest nuclear DNA content was recorded in the population I which has highest percentage of reserpine, while population II having lowest nuclear DNA also showed lowest reserpine content. The hexaploid species R. canescens showed significantly low amount of reserpine. The association of karyotype vis-à-vis genotypic difference with difference in reserpine content has been discussed.
Primary trisomic for chromosome No. 6 (a nucleolar trisomic) has been recovered from the progeny of about 1000 plants of the primary trisomic for chromosome No. 4 (a nonnucleolar trisomic). The paper describes the mode of origin of the non-parental trisomic, its meiotic behaviour, effect on nucleolar organization and plant phenotype.
DNA-content of nuclei from pollen was determined using flow cytometry. The pollen from diploid genotypes gave rise to a 1C- and a 2C-peak of identical size, representing the vegetative and the generative nuclei. Pollen of the interspecific hybrid (L. auratum×L. henryi) presented only 2C- and 4C-peaks, while in the interspecific hybrids (L.×‘Enchantment’×L.pumilum) 1C-, 2C- and 4C-peaks were distinguished. The different C-levels, representing the DNA-contents of the generative and vegetative nuclei in G1 and G2 phase respectively, can be related to haploid and diploid pollen. Results of a meiotic analysis, a number of crossing experiments and pollen measurements agreed with the outcome of the flow cytometric determinations. The flow cytometry method enables the large scale screening of collections of genotypes for their potential of 2n-pollen production.
Detailed microsporogenesis of hexaploid Morus serrata has been studied. This is the first record of natural hexaploidy (2n=6x=84) in the species. Meiosis has been found regular with high frequency of bivalents. The frequency of hexa-, penta-, tetra- and trivalents is considerably less suggesting its allopolyploid nature. Diploid like behaviour of this species with high frequency of bivalents, regular meiosis and high pollen stainability are discussed in relation to its evolution.
Chromosomal architecture of Cicer anatolicum Alef., a wild perennial relative of chickpea, was studied to assist in determining phylogenetic relationships within the genus Cicer L. The diploid chromosome number was confirmed as 2n=16. Mean haploid chromosome complement length and mean chromosome length were 18.88 and 2.36μm, respectively. The karyotype was asymmetrical and characterized by one metacentric, six submetacentric and one acrocentric chromosome pairs. The longest chromosome pair (acrocentric) carried a conspicuous secondary constriction on the long arm. The karyotype of C. anatolicum is compared to that of other annual Cicer species and further phylogenetic relationships discussed.