The technique of chromosome microdissection and microcloning, as a bridge between cytogenetics and molecular genetics, has been widely applied and play an important role in many genetic researches, such as chromosome painting probe isolation, genetic linkage map and physical map construction, and expressed sequence tags generation. To promote the further application of this technique in plants, in the present study, firstly, the experimental procedure was summarized. Secondly, the application status of this technique in plant researches was reviewed and the intractable problems of the application in plant researches were elucidated. Finally, the application of this technique in plants was looked into in the future. The results of the present study have obvious significance in promoting the application of chromosome microdissection and microcloning technique in plants.
Leaf epidermal tissue senses various environmental factors, such as light and pathogens, and is the site of plant responses to environmental changes. The epidermis is composed of stomata distributed at regular intervals and pavement cells shaped like jigsaw puzzle pieces. These characteristic forms are thought to be the basis of the plant’s excellent ability to respond to the environment. I have investigated the mechanisms of cell morphogenesis and distribution to understand the construction of the epidermal tissue at the cellular level. This review describes the quantitative analyses of cortical microtubules and membrane trafficking involved in the morphogenetic mechanisms of pavement cells and an induction system for clustered stomata that involves a sugar solution-based immersion treatment.
It is important to understand how a single circular chromosome in the prokaryotic nucleus evolved into multiple linear chromosomes in the eukaryotic nucleus. In most eukaryotic cells that have ＞∼15 Mbp of genomic DNA, chromosomes remain condensed through all the mitotic phases. Therefore, we observed nuclei of primitive organisms in which linear chromosomes had not been observed previously using conventional methods. Cells of the primitive red alga Cyanidioschyzon merolae, having a genome size of 16.5 Mbp, have been used to study the division of organelles, such as mitochondria, chloroplasts, and peroxisomes. However, morphologically condensed chromosomes have never been observed during mitotic metaphase. Recently, we demonstrated that plastid nuclei are swollen and change from a spherical to a ring shape after being subjected to the glutaraldehyde-fixed-drying method. Using a modified method, we visualized mitotic chromosomes in C. merolae cells. Chromosomal condensation occurred just after the chloroplast division when cells enter metaphase. Thus, chromosomal separation in C. merolae cells likely occurs in a manner similar to that of typical eukaryotic cells. However, mitotic condensed chromosomes were not observed in the primitive green alga Medakamo hakoo, having a genome size of 8 Mbp. Thus, the results support the use of C. merolae as a model for eukaryotic cell analyses.
Chromosomal traits and their variation were investigated for a total of 435 plants from 23 local populations of the three subspecies of Chamaelirium hisauchianum. 334 out of 340 plants of subsp. kurohimense had 2n=44=12L+32S (where L and S denote ‘long’ and ‘short’ respectively) with the base number 22 (x1), and six others were all hyperploids with 2n=45 (2x1+1; five plants) or 46 (2x1+2; one plant). In subsp. hisauchianum, 46 out of 48 plants had 2n=42=14L+28S with the base number 21 (x2), and two others had 2n=42 (2x2) with an aberrant karyotype or 2n=43 (2x2+1). In subsp. minoense, 45 out of 47 plants, like subsp. hisauchianum, possessed 2n=42=14L+28S (x2=21), and two others showed 2n=43 (2x2+1) or 45 (2x2+3). All of the observed chromosomal variants exhibited structural heterozygosity and presumably arose by fission, fusion, and duplication probably derived from irregular chromosomal disjunction. The chromosomal variants found in all populations examined amounted to 2.3% on average. Pollen stainability with cotton blue in four chromosomal variants of subsp. kurohimense and minoense was lower than in chromosomally normal plants. Some topics relevant to the results were also discussed, comparing with the data previously reported for C. japonicum and C. koidzumianum that markedly differ in the mating system as well as some chromosomal traits.
The genus Vateria L. (Dipterocarpaceae) with its three species namely, V. indica, V. copallifera and V. macrocarpa are distributed from India to Sri Lanka. The genus so far has not been screened for its cytological characters. In the present investigation, the mitotic chromosome number of 2n=22 and basic karyomorphology of V. indica were reported for the ﬁrst time.
Chromosome numbers of five Alyssum species (A. aizoides Boiss., A. aureum (Fenzl) Boiss., A. baumgartnerianum Bornm. ex Baumg. A. constellatum Boiss. and A. xanthocarpum Boiss.) from Turkey have been reported for the first time. A. aizoides and A. baumgartnerianum are tetraploid (2n=4x=32) while A. aureum, A. constellatum and A. xanthocarpum are diploid (2n=2x=16).
Pinus pumila, which habits around the timber line in Japanese mountains, propagates from adventitious roots of creeping or belowground stems and from seeds that are dispersed by animals. In an attempt to detect heterozygous simple sequence repeat (SSR) alleles in the nuclear genome of P. pumila, which may be useful to identify individuals in natural populations, we performed PCR using the DNA from this species and primer sets that have been reported for P. strobus SSR (Echt et al. 1996). Aligned subclone sequences originating from RPS150 product suggested that this locus included at least two [ga(t/g)]n alleles, [gat]3[gag]3 and [gat]3[gag]1[gat]1, while the direct sequence of RPS160 product included a single SSR allele of [acag]3[gcag]1[acag]3. This is the first report of the heterozygous nuclear SSR locus in P. pumila.
Investigation of aberrations caused by gamma radiation in mitosis and meiosis might be fundamental to elucidate the interaction between radiations and biological systems. To identify the effects of the various doses of gamma radiation (25, 35, 45, 55 Gy) on mitotic and meiotic traits and agronomical features, a field experiment and microscopy assays were conducted on M2 generation of Vicia faba cv. Saraziri. Various types of mitotic and meiotic anomalies including laggard chromosomes, precocious movement of chromosome, anaphase and telophase bridge, chromosome fragments, chromosome stickiness, micronuclei, disturbed anaphase, vagrant chromosomes, the trinucleate status in telophase and tripolar anaphase were observed in root meristem cells and pollen mother cells (PMCs). The meiosis of PMCs showed less sensitivity towards gamma radiation than mitosis of root meristem cells. Among different stages of mitosis and meiosis, the most anomalies in terms of frequency were attributed to anaphase in mitosis and telophase II in meiosis. The recorded data of different anomalies confirmed that the micronuclei in telophase of mitosis and meiosis had the most frequencies in all gamma ray doses. The effects of different doses of gamma rays on agronomic traits including the number of pods per plant, number of seeds per pod, number of seeds per plant, and seed yield per plant were significant and the values decreased as the irradiation dose increased. Moreover, increasing irradiation doses caused a delay in flowering, pod setting, and pod ripening period. The highly negative correlations between mitosis and meiosis anomalies and agronomical traits were reported in this research.
Previous chromosome information is restricted to Dipterocarpoideae, one of the two subfamilies of Dipterocarpaceae, and no chromosome information is available for another subfamily Monotoideae. Here we present the first karyomorphology of Marquesia macroura (2n=22) (Monotoideae), as well as of four species (2n=22) of four genera in tribe Dipterocarpeae and five species (2n=14) of tribe Shoreae in Dipterocarpoideae. Comparisons within Dipterocarpaceae and with Sarcolaenaceae (2n=22) sister to Dipetrocarpaceae in the light of phylogenetic relationships show that the basic chromosome number x=11 is plesiomorphic and x=7 apomorphic in Dipterocapaceae. Based on available information, tribe Shoreae (x=7) has a uniform karyotype where all chromosomes have a centromere at median position, while the rest of the family (x=11) have a diverse karyotype in terms of the frequency of chromosomes with a centromere at median, submedian and subterminal position. We discussed the meaning of lability of karyotype in chromosome evolution.
Allium cepa (2n=16) assay is conducted to ascertain cytotoxicity of two most used hazardous chemotherapeutic drugs namely, cyclophosphamide (CP) and 5-fluorouracil (5-FU) (doses at much lower than pharmaceutical concentrations—0.025, 0.050, 0.100, 0.250 and 0.500 g L−1 for 24 h) to ascertain possible “Cytothreat” of the drugs to the ecosystem on disposal, and in non-targeted cells of the host system. Mitotic aberrations encountered in both dividing (stickiness of chromosome, chromosomal disintegration(s), ring(s), laggards, bridges and tri- and multipolarity) and resting (cells with micronucleus, binucleate and giant cells, cells with cellular and nuclear deformities and anucleate cells) cells ranges from 0.00 to 33.04% and 3.49 to 7.55% respectively in CP treatments, and 0.00 to 21.24% and 0.00 to 6.07% in 5-FU treatments. Both the drugs induce similar aberration types; however, the effect is higher in CP than 5-FU. Result suggests that the chemotherapeutic drugs are clastogenic affecting spindle apparatus and cellular metabolism. The present study highlights the “Cytothreat” of the drugs and warrants safe dose application for ecological safety and non-targeted cells of the host system.
Salvia officinalis L. (2n=2x=14) is a perennial plant from Lamiaceae family. It has a long history of medicinal and culinary use. This study was aimed to investigate the polyploidy induction in S. officinalis L. via seed treatment with colchicine concentrations of 0, 0.05, 0.1, 0.25 and 0.5% at 12, 24 and 48 h treatment time as a factorial experiment based on the completely randomized design with three replications. Polyploidy induction firstly detected by morphological, anatomical and physiological characteristics and confirmed by flow cytometry and chromosome observation from leaves. Results showed that the colchicine concentration and treatment duration have significant effects on the survival rate of plants and the percentage of tetraploidy induction. The percentage of survived plants was decreased by increasing the treatment time and colchicine concentration. Meanwhile, the highest percentage of induced tetraploid plants was obtained at 0.25 and 0.5% colchicine with a treatment time of 48 and 24 h, respectively. Tetraploid plants specified by increasing in leaf length, leaf width, plant height, number of leaves, number of nodes, internodes length, stomata size, catalase, peroxidase and polyphenol oxidase activities, total phenolic and flavonoid contents and antioxidant capacity and on the contrary, decreasing in stomata count as compared with diploid ones.
Three species of Zephyranthes Herb. viz. Z. candida (Lindl.) Herb., Z. carinata Herb. and Z. tubispatha Herb. were cytotaxonomically studied to characterize and elucidate probable evolutionary relationship among them. These species were found to possess different chromosome number and karyotype formula such as 2n=38=32m+6sm in Z. candida, 2n=24=14m+10sm in Z. carinata and 2n=48=16m+32sm in Z. tubispatha. A pair of satellites was observed only in Z. tubispatha. Despite three Zephyratnes species showed close relationship with reference to morphological characters, however, they displayed notable differences in the karyological study. The present cytogenetical and taxonomical findings indicated that Z. tubispatha was relatively advanced and Z. carinata was primitive from the evolutionary point of view.
Genome size provides important information in ecology and evolution as well as genomics. Genome size may be different between the sexes within a species. However, little information on the genome size of both sexes is available, particularly in ulvophycean marine green algae, because few methods of genome size estimation are suitable for these algae. We developed a method to examine the genome sizes of males and females in the dioicous ulvophycean marine green alga Monostroma angicava. We examined three methods to isolate haploid nuclei: 1) chopping of a haploid gametophyte; 2) homogenization of protoplasts made from haploid gametophyte cells; and 3) homogenization of gametes and found homogenization of gametes to be the most suitable method for isolation of nuclei in M. angicava. Isolated nuclei were stained with propidium iodide. We measured the fluorescence intensity of nuclei using flow cytometry and successfully estimated the genome sizes of males and females as 178.8 Mbp and 185.4 Mbp, respectively, using Arabidopsis thaliana and Brassica rapa as standard plants with an internal standard method. The genome size of males was slightly smaller than that of females. This may be due to the difference in the length of sex-specific genome regions.