Chromatin remodeling represents a dynamic change of open or closed chromatin structure, which is closely related to the transcriptional regulation. The regulation by the Switch/Sucrose non-fermenting (SWI/SNF) chromatin remodeling complex is crucial for embryonic, vegetative, and reproductive development. A catalytic ATPase of the SWI/SNF complex, BRAHMA (BRM), is evolutionarily conserved among eukaryotes. We focus on the role of plant BRM in the regulation of gene expression by altering the accessibility of the target DNA. We also introduce the interacting partners required for the recruitment of BRM to the target loci.
In vitro propagation of Psidium guajava L. has been significant for breeding programs and conservation. Hereby, distinct explants are chosen and inoculated into media supplemented mainly with the growth regulators 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA). As growth regulators have been considered the main inducers of somaclonal variation (SV), this study verified the occurrence of karyotype and DNA sequence variation in P. guajava ‘Paluma’ and ‘Cortibel XIII’ plantlets. Plantlets propagated in different media—4.44 µM BAP, 4.44 µM BAP/0.54 µM NAA, or 4.44 µM BAP/2.70 µM NAA—were assessed concerning their nuclear 2C value, karyotype, and DNA sequence. Nuclear DNA content and chromosome number of all plantlets were 2C=0.95 pg and 2n=22, respectively, identical to P. guajava. Therefore, the media did not promote karyotype changes. In contrast, molecular analysis showed appearance and disappearance of allele forms. These alterations in the DNA sequence were found in plantlets propagated in all media, indicating that BAP and especially NAA are related to the event of somaclonal variation (SV). Based on these results, the media most employed for P. guajava induced SV at the DNA-sequence level. This approach provided data about the more appropriate media for propagation of P. guajava.
Polyploidy is a typical trait in human cells (2n=46) in cancer diseases. In the present investigation, polyploid cells (2n＞16) due to erroneous division of centromere at metaphase are induced in root tip meristem of Allium cepa following treatments (0.25%-72 h, 0.50%-48 h, and 1.00%-24 h) of colchicine. The objective of the work is to foresee whether or not the induced ploidy level can be ameliorated by administering the doses of aqueous extracts of Curcuma longa rhizome and Nigella sativa seeds. Cisplatin at its pharmaceutical dose (1 mg mL−1) is used as a positive control in the study. Results show the formation of enhanced polyploid cell frequency in the root meristem of A. cepa in a dose-dependent manner and effectivity of the aqueous plant extracts in ameliorating the polyploid frequency is differential. Cisplatin demonstrates total inhibition of cell division and apoptosis of cells. From the results, it can be inferred that the plant resources having enthnomedicinal properties could be potential in cancer treatment if the selection of appropriates dose(s) could be made. Thus, the present investigation is significant in suggesting the further exploration of ethnomedicinal resources in the development of low cost, readily available, household treating agents in cancer therapy through proper scientific intervention followed by a clinical trial.
Analysis of the ploidy levels between different plant species can help the breeder to select strategies for cross-based breeding programs. In this study, various ecotypes of Festuca pratensis, F. arundinacea, F. rubra, Lolium perenne, L. multiflorum, and L. hybridum were cytologically characterized and grouped based on their chromosomal and karyotypic parameters. Moreover, 5S and 45S rDNA loci were determined by fluorescence in situ hybridization (FISH) in four species. Based on the mitotic chromosome complements, all the F. arundinacea and F. rubra ecotypes were hexaploid, L. multiflorum ecotypes were tetraploid and both diploid and tetraploid ecotypes of L. perenne and L. hybridum were identified. All ecotypes were located in the 2A class of Stebbins’s asymmetry, except for Fa2 (F. arundinacea) from Iran, Fr1 (F. rubra) from Finland, and Lp3 (L. perenne) from Switzerland, which was classified as 2B. One or two B chromosomes were observed in several individuals of an Iranian F. pratensis. In a cluster analysis based on karyotype parameters, Lp2 (L. perenne) from Switzerland and Fp2 (F. pratensis) from Sweden showed the minimum distance, suggesting that their crossing might be successful. FISH identified three 5S and two 45S rDNA loci in F. arundinacea, one 5S, and one 45S rDNA loci in F. pratensis, three 5S and two 45S rDNA loci in F. rubra, and one 5S and three 45S rDNA loci in L. hybridum.
Five endemic Muscari taxa in Turkey are examined in terms of chromosome number and morphology. Muscari sivrihisardaghlarense (2n=18), M. serpentinicum (2n=18), M. atillae (2n=18) and M. ufukii (2n=18) are diploid. M. tuzgoluense is polyploid with 2n=36 chromosome number. Chromosome counts have confirmed the previous reports that Muscari genus is x=9 of basic chromosome number. The chromosome number and morphology of these species are reported for the first time. The karyotypes have the predominance of metacentric and submetacentric chromosomes. Six quantitative asymmetric indices were used to evaluate the karyological characteristics of the species, and these results increase our karyological knowledge about the species.
The mitotic chromosomal complement of Prosopis juliflora from a population of Mexico was analyzed using the method of air drying and Giemsa staining. In addition to an unequivocal and constant chromosome number 2n=4x=56, detailed characteristics of its general chromosomal morphology and karyotype are described for the first time, where metacentric (m) and submetacentric (sm) chromosomes and few subtelocentric (st) predominate. Only two SAT chromosomes were recorded with microsatellites on short arms in apparently st chromosomes and their nucleolar organizer region (NOR) condition was verified by locating them close to or embedded in the nucleolus of prometaphase cells. A maximum number of two nucleoli in interphase nucleus and rarely traces of two additional micronucleoli were also corroborated. The average chromosome size exhibits a notable reduction compared to that recorded in diploid species of the genus. Taken together, these results show P. juliflora as an allotetraploid taxon whose complements show amphiplasty or nucleolar dominance. Finally, it is proposed that the current distribution of this species, adjusted mainly to coastal environments, responds to an adaptive and functional novelty as a result of a hybrid condition.
The chromosome numbers and karyotypes of eight species of the genus Muscari distributed in Turkey were analyzed. These taxa are M. macrocarpum Sweet, M. racemosum Mill., M. aucheri (Boiss.) Baker, M. armeniacum Leichtlin ex Baker, M. sivrihisardaghlarensis Yıldırımlı & B. Selvi, M. discolor Boiss. & Hausskn, M. botryoides (L.) Mill. and M. neglectum Guss. Five of them (M. racemosum, M. aucheri, M. sivrihisardaghlarensis, M. discolor, and M. botryoides) are endemic in Turkey. The chromosome number of all studied taxa were determined as 2n=2x=18, while M. neglectum had the chromosome number of 2n=4x=36. Haploid chromosome lengths varied 24.94 µm (M. armeniacum) to 119.85 µm (M. racemosum) among species. Karyotype analysis indicated that Muscari taxa generally have a median point (M), median (m), and submedian (sm) chromosomes. In addition, only M. racemosum has one subterminal (st) chromosome pair. Satellites were observed in M. racemosum and M. botryoides. The karyotypes of M. sivrihisardaghlarensis was determined for the first time in this study.
In the budding yeast Saccharomycodes ludwigii, four spores in an ascus are in pairs of two spores, and the two spores of opposite mating type are tightly tethered by an interspore bridge, a so-called ledge. A pair of spores germinates and immediately conjugates to form zygotes in rich medium. We found that the interspore bridges are detached from spore walls during germination of spores and zygote formation. We successfully isolated the interspore bridges morphologically intact from the spores by a combination of treatment of zygotes with Zymolyase, sonication, and sucrose density gradient centrifugation. The interspore bridges are disc structures with a diameter of approximately 2 µm and a thickness of approximately 0.5 µm. The interspore bridges are composed of three layers, with the outer two being stained by Calcoflour. Detailed observations of the sporulation process suggested that the interspore bridges are formed concomitant with spore wall formation. This is the first report of the isolation of interspore bridges from yeast.
Saccharum spontaneum, the wild species of sugarcane, is an important germplasm resource with exceptional properties of pest and disease resistance and stress tolerance. Chromosomal diversity and its evolutionary dynamics in this species have been revealed through the study of 88 clones collected from the states of Punjab and Haryana, India. Twelve cytotypes were identified with five euploids [2n=40 (5x), 48 (6x), 56 (7x), 64 (8x), 72 (9x)] and seven aneuploids (2n=50, 52, 54, 60, 70, 74, 76). The random meiotic analysis showed predominant bivalent formation. The clone IND 16-1847 (2n=72) showed meiotic abnormalities like univalents, laggards, bridges, and multipolar chromosome segregation. Analysis of the evolutionary origin of different cytotypes revealed the independent, as well as multiple origins and the ploidy evolution, might be a network type rather than in a single direction. This leads to the increased allelic and genetic variation and gene flow among different ploidy levels of S. spontaneum.
Plant development depends on the activity of stem cells. The shoot branch, which is called a tiller in grasses, is derived from stem cells in the axillary meristem, which continuously emerges in the leaf axil during plant growth. TILLERS ABSENT1 (TAB1) and FLORAL ORGAN NUMBER2 (FON2) play important roles in axillary meristem development in rice. In this process, TAB1 is required for stem cell maintenance, whereas FON2 negatively regulates stem cell fate by restricting TAB1 transcription. FON2 encodes a signaling molecule, which was originally identified as a negative regulator of stem cell maintenance in the floral meristem, and is known to act in the same genetic pathway as FON1 encoding a putative receptor of FON2. Here, we investigated whether FON1 is involved in axillary meristem development. The fon1 mutation did not affect axillary meristem development or tiller formation. Consistent with this result, FON1 expression was not detected throughout axillary meristem development. In addition, the fon1 mutation, unlike fon2, did not rescue the failure in tiller formation in tab1. Therefore, the roles of FON1 and FON2 likely differ from each other in axillary meristem development, and FON1 seems not to be involved in stem cell maintenance. These results also suggest that FON2 might regulate axillary meristem development via a receptor other than FON1.
The toxic effect of iron in nano-composite and salt form was tested on onion (Allium cepa L.) root tip cells in this study. Heavy metals are core pollutants of the environment but their toxicity is dose dependant and has an issue in the state of Odisha particularly in iron contaminated soil for crop production and its food chain associated human health hazard. Plants growing in such an environment are the mute witnesses to these contaminations and crop plants played a major role as carriers of heavy metal. Onion is a biomarker that is used for various genotoxic studies as it has large chromosomes, pronounced mitotic phases in the root tip. Root growth dynamics are very sensitive to any kind of pollution. Iron accumulation within the plants can be toxic at the cellular level. Stable iron oxide/ silica nano-composite (Fe2O3 NC) is characterized by transmission electron microscopy (TEM). An increase in chromosomal aberrations in root meristems along with lipid peroxidation and a decrease in SOD activity was clearly seen after treatment with FeNC. Since, iron oxide nanocomposites, owing to their submicron dimension, permeate into the intracellular space and produce hydrogen peroxide that leads to an increase in an oxidative burst in the cell. To mitigate oxidative damage, scavenging of antioxidative enzymes were found in FeNC treatment more as compare to its salt form. However, a high dose of FeNC found carcinogenic in A. cepa root tip that might have the potential for human health hazards.
Begonia sect. Coelocentrum is a characteristic plant group in the limestone karsts of southern China and northern Vietnam and yet previous chromosome information is restricted to ca. 50 species and their karyotypes have never been investigated. Here we report the cytological investigations of 15 species of sect. Coelocentrum, including four karyotype analyses that are the first report in sect. Coelocentrum, ten species reported cytologically for the first time, and five species that were re-examined. Incorporating recent and present studies, chromosome numbers of 56 of the 82 species in sect. Coelocentrum are now available. Among the 56 species, 55 have a stable and common chromosome number of 2n=30, with a few species showing aneuploidy numbers of 2n=31, 32, 33, 35, 36, and a triploid number of 2n=45. Karyotypic formula of the four investigated species are uniform as 2n=30=8m+22sm(st). Based on our and previous studies, the chromosome evolution in Begonia sect. Coelocentrum is discussed.
Erianthus is a wild related genus of sugarcane. Its introgression is expected to impart better biomass production, multi ratoonability, and disease and pest resistance to the sugarcane cultivars. In this study, the introgression pattern of the wild genome, E. procerus, has been analyzed in the three consecutive generations. The field performance concerning important agronomic traits and reaction to one of the major diseases, red rot, also has been studied. We report here for the first time the chromosome composition of fertile E. procerus × S. officinarum F1, BC1 (F1×sugarcane cultivar, Co 06027), and BC2 (BC1×sugarcane cultivar, Co 775) hybrids via genomic in situ hybridization (GISH). The F1 resulted from 2n+n chromosome transmission, while BC1 and BC2 from n+n transmission. The hybridity of these clones was confirmed with the presence of both Erianthus and Saccharum specific amplified bands of 5S rDNA. The field evaluation revealed that though BC1 and BC2 hybrids recorded significantly higher stalk number and comparable stalk yields, the juice quality traits need further improvement with few more backcrosses. These Erianthus introgressed hybrid clones proved to be a potential source for red rot resistance in future sugarcane cultivars. This study is aimed to identify the agronomic value of chromosomes from E. procerus and to conduct targeted breeding based on these information.