An efficient and rapid protocol has been reported for the first time for plant regeneration through somatic embryogenesis from corm and young corm buds of Iphigenia indica Kunth et Benth, an important colchicine yielding threatened medicinal plant of Colchicaceae. Soft, friable and well proliferating callus was initiated in Murashige and Skoog's modified basal medium (MS) supplemented with 3% (w/v) sucrose, 0.05 mg/l (w/v) each of nicotinic acid, thiamine-HCl, pyridoxine-HCl, ascorbic acid, 0.1 mg/l (w/v) glutamine, 0.25% (w/v) Gelrite® and a combination of α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) (2.0/0.5 mg/l). Such callus became nodular and embryonic in nature after transferring to the same MS modified medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) (1.0 mg/l). The globular embryos were observed in this medium after 4 weeks in culture. The transition of globular stage occurred when embryonic callus mass was shifted to half strength of MS medium containing 0.1 mg/l kinetin with production of maximum percentage of embryos showing distinct epicotyl and hypocotyl differentiation (65.4±0.46). These growing embryos developed into complete plants with well-formed root and shoot systems in the same medium containing 1% (w/v) sucrose. All the regenerates showed stability in chromosome number (2n=22) with 87.4% survival rate after 2–3 weeks of hardening. High Pressure Liquid Chromatography (HPLC) analysis revealed higher amount of colchicine in the regenerated corm-like bulbous structures than in vivo corms. However, both regenerated and in vivo shoots contained negligible amount of colchicine.
Detailed chromosome analysis of 8 populations of Xylocarpus granatum showed a constant somatic chromosome numbers of 2n=48 with a very symmetric karyotype. Structural details recorded no such major variation in the chromosome morphology. Random amplified polymorphic (RAPD) markers were used for determining the genetic diversity among 8 populations of this minor tree mangrove species. Individuals collected from several sites in north-east coast of India were analyzed for their genetic relationship. A total 444 amplicons were generated among the ecotypes out of which ~67% bands were found polymorphic. Inter population polymorphism among 8 populations of X. granatum varied between 36.25 to 72.5%. Clustering based on similarity index was done following Unweighted Pair Group with Arithmetic mean (UPGMA) method and intra-genetic relationships were analysed. The obtained dendrogram of the RAPD data showed prominent patterns of interpopulation relationships that are discussed in the light of the respective habitats of the ecotypes distributed in different mangrove pockets of the north-east Indian sea coast. It was evident from RAPD data that high degree of divergence exists among 8 studied populations, which suggests their adaptation in various microclymatic condition is suitable for the specific habitat of a particular ecotype.
Partial or complete stickiness of chromosomes and disorientation of spindle were the major anomalies observed in meiocytes of Trigonella plants raised from seeds treated with different concentration of sodium azide for three durations. Other aberrations were unequal separation, non synchronous division, bridge, laggard, stray etc. The pollen fertility and yield showed an increase over control despite the high frequency of stickiness and spindle disorientation. Yield was positively correlated with stickiness, indicating a balancing/regulatory effect of stickiness at the time of gamete formation.
In yeast, melatonin had previously been shown to be formed and to be metabolized to other 5-methoxylated indoles. We now demonstrate that an alternate melatonin metabolite, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), is converted by S. cerevisiae to N1-acetyl-5-methoxykynuramine (AMK), which is subsequently released to the culture medium. By means of an NO donor, PAPA-NONOate, AMK extracted from the medium is nitrosated to 3-acetamidomethyl-6-methoxycinnolinone (AMMC). The deformylation of AFMK was enhanced by aspartate or glutamine. This is not a general phenomenon of providing nitrogen sources, since asparagine and arginine were slightly, and guanidine strongly inhibitory, whereas addition of ammonium caused only small increases. Experiments with glutamine or high ammonium indicate the formation of another metabolite, N-[2-(6-methoxyquinazolin-4-yl)-ethyl]-acetamide (MQA).
The seven different primary trisomics, isolated by the present authors in grass pea (Lathyrus sativus L.) transmitted at reduced rate than the expected 50% in the progeny of selfed trisomics and in the intercrossed progeny of trisomics and diploid plants (2n=14). Among the trisomics, type-IV (ternate-verticillate leaflet) exhibited the highest transmission rate (29.3%) while it was minimum (16.0%) in case of type V (alternate leaflet) in selfed progeny. When trisomic plant was used as seed parent during intercrossing with normal diploids, rate of transmission of trisomy was found to be higher than when it was used as pollen parent. Several factors like seed size, rate of germination and survival of seedlings, trivalent/univalent frequency and pollen sterility might affect the transmission of trisomics in grass pea. Small, light-weight seeds germinated poorly and survival of its seedlings was not good at all but higher number of trisomic plants appeared from small sized seeds than from large, heavy weight seeds although it germinated and survived at better rate than small seeds. Higher frequency of trivalent during metaphase-I as well as transmission rate of extra chromosome were encountered in trisomics I, II, IV and VI than types III and V where univalents appeared more frequently than trivalents at microsporocytes. Among the trivalents, frying pan configuration was the lowest in type IV showing highest rate of transmission, while this configuration was maximum in PMCs of type V exhibiting lowest rate of transmission. Increased frequency of trivalent led to high incidence of pollen sterility and influenced rate of transmission of the extra chromosome in trisomic plants through anaphasic disturbances.
Caltha palustris L. (Ranunculaceae), popularly known as Kingcup or Marsh Marigold is a polymorphic species distributed in the cold temperate regions of western Himalayas. The species exhibits considerable amount of intraspecific morphological and chromosomal diversity involving polyploidy, aneuploidy and hybridization. Besides, some individuals also show the presence of B-chromosomes. Presently three populations from the cold desert region of Kullu and Lahaul-Spiti districts of Himachal Pradesh have been studied for detailed meiotic studies. These populations which uniformly show the presence of 16 bivalents at M-I are tetraploid on x=8. Presence of eight large sized and eight small sized bivalents at M-I, suggest these populations to be allotetraploid. Majority of the individuals in one of the populations show normal meiotic course and high pollen fertility. However, in the other two populations, the individuals show inter PMC transfer of chromatin material at various stages of meiosis and associated meiotic irregularities such as chromosome stickiness, pycnotic chromatin, late disjunction of bivalents, micronuclei and chromatin bridges at anaphases and telophases. Besides, the chromatin migration also results in the formation of aneuploid with 8, 11 and 13 bivalents and anucleated PMCs. Although the phenomenon of cytomixis does not affect apparent pollen fertility but it surely resulted into heterogenous sized pollen grains. Although the genetic constitution and fate of such apparently fertile heterogenous sized pollen grains is yet to be ascertained, but their possible role in the development of individuals with varied chromosome number could not be ruled out. The phenomenon of chromatin transfer in the species seems to be under direct genetic control as the individuals with and without cytomixis found to grow in the same environmental conditions.
For this knowledge, the discovery of the chromosome trisomy 22 in siamang (Symphalangus syndactylus) is the first report. To our scheme, blood sample was collected from one female of Khao Kheow Open Zoo (KKOZ), Chonburi province, Thailand. Chromosomes were prepared by lymphocyte cells culture at 37°C for 72 h then stained by G banding technique. The result indicated that diploid (2n) of siamang was 51 (one irregular chromosome was found). The autosome consists of 47 metacentric and submetacentric, 2 telocentric chromosomes. The X chromosome was metacentric chromosome. The increasing of one metacentric chromosome 22 lead to the presence of the irregular chromosome and the changing of 2n=50 to 2n=51. The augmentation of chromosome 22 was found in all metaphase cells of the entire study. We suggested that the chromosome increasing is a consequence from the non-disjunction in meiosis cell division.
P. squamulatum Fresen. is an important Pennisetum species by virtue of its characters, such as, apomixis, perenniality and stress tolerance, which can be utilized for pearl millet improvement. This species is hitherto believed to be 2n=6x=54, however, recent reports of 2n=56 cytotypes rendered to recheck the ploidy status. In present study, meiotic system of F1 and advanced hybrids, such as F2, F1 sibs, and BC1, involving P. squamulatum (2n=56) and P. glaucum (2x and 4x) were investigated following a scheme to sequentially reduce P. squamulatum chromosome complement to half, in order to determine its ploidy. The cytological results indicating high bivalent frequencies in these generations confirmed octoploid (instead of 6x) nature of P. squamulatum, alongwith its basic chromosome number as 7 (similar to pearl millet) with its allo-octoploid (or auto-allo octoploid) status. On the basis of cytogenetical studies viz. crossability, DNA content, genetic relatedness and cytology of advanced hybrids, placement of P. squamulatum in secondary gene pool of pearl millet is supported.
The pseudoautosomal region (PAR) is the chromosomal region where XY sex-chromosome pairing occurs. The boundary of the PAR delineates the XY pairing and non-pairing regions, but detailed information about this region is lacking. In this study, we analyzed the sequences adjacent to SlX1 and SlY1 in the dioecious plant Silene latifolia. SlX1 and SlY1, which are linked to the X and Y sex chromosomes, respectively, are thought to be closely linked to the PAR. The Sl-distal-satDNA is a satellite DNA found at the ends of S. latifolia chromosomes. The chromosomal distance between SlX1/SlY1 and Sl-distal-satDNA has not been examined. It was probably almost entire the PAR. However, the region between SlY1 and the Sl-distal-satDNA could be amplified in PCR. The nucleotide sequence between SlY1 and the Sl-distal-satDNA was determined following PCR amplification and compared to the sequence adjacent to SlX1 using BAC clones. In addition, a new male-specific STS marker, Y202, was designed based on the sequence adjacent to SlY1. Y202 as well as SlY1 were mapped on the Y chromosome using a panel of deletion mutants and FISH analysis. Our data suggest that the sequences adjacent to SlX1 and SlY1 do not simply follow a gradient of sequence divergence, a feature that was thought to allow the functioning of the PAR boundary. Therefore, recombination suppression in the XY chromosomes probably occurs via other mechanisms.
Present study reveals the occurrence of inter PMC transfer of chromatin material in the PMCs of ‘Seabuckthorn’ (Hippophae rhamnoides L.). The migration of chromatin is observed from early prophase up to telophase-I. In majority of the cases 2–4 PMCs are involved in chromatin transfer, however in rare occasions migration of chromatin occurs in groups. The migration of chromatin is observed to be partial as well as complete, which resulted into the formation of anucleated, hypo and hyperploid PMCs. In rare cases, direct fusion between two PMCs at AI lead to the formation of a polyploid PMC with 36 chromosomes. As a consequence of cytomixis various other associated meiotic anomalies such as chromatin stickiness at MI and late disjunction of bivalents at AI, pycnotic chromatin, bridges and laggards at anaphases and telophases are resulted. Microsporogenesis is also abnormal resulting in the formation of dyads, triads, and polyads with micronuclei. The cytomixis though do not cause much pollen sterility but it surely results in the formation of heterogenous sized fertile pollen grains. The pollen grains are classified into small, medium and large sized with medium sized pollen grains being in high frequency. The role of such fertile, especially, small and large sized pollen grains, in the origin of plants with aneuploid and polyploid chromosome number, can not be ruled out. The present meiotic count of n=9 is the first record for the study area.
A study was carried out to understand the flowering behaviour of some commercial sugarcane clones of sub-tropical India and the changes taking place in the target tissues in relation to flowering. The clones studied showed a wide range of flowering behaviour. The shoot apex tissues showed initiation of changes much before the short blade stage. The changes were characterized by an increase in the length and width of the shoot tip tissues and primordial initiation. These changes could be observed 4–5 weeks before the initiation of short blade, which is considered to be an early stage at which flowering could be detected. This gives an idea about specific stages of the crop at which, changes in gene expression patterns during the transition from vegetative to reproductive stage may be observed.
Interspecific variation and molecular phylogenetic analysis among the four species of Astrophytum i.e.A. asterias, A. capricorne, A. myriostigma and A. ornatum of the family Cactaceae were studied using cytological and molecular markers. In all the four species, the somatic chromosomes found were 2n=22. Though they showed a high level of similarity in the number of chromosomes, karyotype analysis revealed species-specific chromosomal characteristics. The total chromosome length varied from 53.05 μm in A. aterias to 60.12 μm in A. capricorne. The chromosome volume varied from 41.82 μm3 in A. ornatum to 61.65 μm3 in A. myriostigma. The centromeric index (TF %) among the four species varied from 35.93% in A. myriostigma to 45.25% in A. capricorne. The symmetrical karyotype with same number of secondary constricted chromosomes in A. asterias & A. myriostigma suggests their close affinity between them. The 4C DNA contents were varied significantly from 8.95 pg in A. aterias to 10.23 pg in A. capricorne. The amplification products in PCR generated RAPD analysis of the four species, revealed a total of 315 bands with fragment size ranging from 0.21 kb to 3.1 kb that showed high correlation of A. asterias with A. aterias and A. capricorne with A. ornatum that were also confirmed from the karyotype analysis. Analysis of the nuclear DNA content showed significant variation in the amount of 4C DNA between the three species. The correlation coefficients showed the various chromosomal and nuclear parameters were interdependent to some extent suggesting interspecific relationship between structural and molecular changes of the genome architecture during evolution of speciation.
Seventeen chromosome counts of 15 taxa (15 species) in the tribe Anthemideae of the family Astraceae are reported. All taxa were collected from Zanjan, Iran. Six counts are new reports (including Achillea talagonica, Anthemis coleopoda, Anthemis haussknechtii, Tanacetum pinnatum, Tanacetum polycephalum, and Tanacetum kotschyii), four are not accordance with previous counts (or are new reports for ploidy levels) and reminders are confirmation of very limited (one to six records) previous data. All of studied taxa have the basic number x=9, with ploidy levels ranging from 2× to 10×.
Plastids were derived from free-living cyanobacterium ancestors that were engulfed by a primary non-photosynthetic eukaryotic host cell and subsequently evolved into plastids. Consistent with their bacterial origin, plastids use the bacterial FtsZ ring, the gene of which was transferred to the host eukaryotic nucleus over evolutionary time. However, recent genome sequencing projects show that most of the other proteins once involved in bacterial division have been lost. Here we show, highly sensitive immunofluorescence analysis using plastid FtsZ antiserum revealed that plastid FtsZ forms two types of ring structures during plastid division: (i) the 1st FtsZ ring is formed at the division site to constitute the foundation of the plastid division machinery and (ii) the 2nd FtsZ ring is formed at a right angle with the 1st FtsZ ring. One notable point is that the 2nd FtsZ ring disappears at the end of plastid division. This result suggests that the nuclear encoded plastid FtsZ may function in daughter plastids, in addition to foundation of the plastid division machinery.
The spruce, genus Picea is distributed throughout Eurasia and North America. Because all Picea species have the same chromosome number (2n=24) and very similar karyotypes, comparative karyotype analysis using traditional staining methods is difficult or impossible. Fluorescent in situ hybridization (FISH) with probes of 45S rDNA, 5S rDNA, and Sau3A repetitive family is reported a powerful tool for comparative karyotype analysis in some species of Picea. We report here FISH karyotypes in 11 Picea species and compare them each other. Comparative FISH karyotyping clarified the interspecific relationships of eight Eurasian and seven North American species. Eurasian species displayed conservative FISH karyotypes, while North American species showed variable FISH signal patterns. Two American species, P. rubens and P. mariana, were very similar to Eurasian species in FISH karyotype. We discuss the differences at each FISH signal site and compare the interspecific relationships of FISH karyotypes to molecular phylogenetic trees reported in Picea.