Nucleomorphs are the reduced nuclei derived from endosymbionts found in some secondary symbiotic algae. Research into the nucleomorph has provided many insights into its role as a product of secondary endosymbiosis, as well as the resulting genome reduction and gene transfer. Recently developed biological techniques and bioinformatic tools have enabled us to examine the characteristics of nucleomorphs more comprehensively than was previously possible. Moreover, new approaches in synthetic biology have begun to emerge that may provide a valuable platform to study artificial endosymbiosis. Together, these technologies could allow greater insights into the mechanisms and regulation of genomic dynamics within the nucleomorph.
Ten germplasms of three Crotalaria species viz. C. pallida (Acc. No. 4250, 4803, 4805, 4806, and 4807), C. incana (Acc. No. 4790, 4801, 4804, and 4809), and C. juncea (Local) were investigated cytogenetically through Chromomycin A3 (CMA) and 4′-6 diamidino-2-phenylindole (DAPI) fluorescent bandings. After CMA-banding, 10 Crotalaria germplasms showed 31 centromeric and 34 terminal bands which indicated a tendency of accumulating GC-rich sequences at centromeric regions or chromosomal ends. The number of DAPI bands was less than that of the CMA bands found in different germplasms of Crotalaria. Maximum terminal DAPI-bands indicated a tendency of accumulating AT-rich sequences at the chromosomal ends. Few chromosomes of Acc. No. 4803 of C. pallida and 4804 of C. incana could be used as a marker of respective germplasms due to their unique DAPI-banding pattern. Fluorescent banding revealed the occurrence of genomic alteration within these germplasms. In Acc. No. 4790 and 4804 of C. incana, 2n=17 chromosomes were observed indicating its the aneuploid origin that correlates with their phenotypic features like seedless pod formation. The diversity in CMA- and DAPI-banded regions in ten germplasms of Crotalaria from Bangladesh can help in further breeding programs.
Irano-Turanian floristic region in Turkey appears to be the center of origin of Crepis foetida subsp. rhoeadiflolia (Asteraceae). In this study, karyotype and flow cytometric analyses of six Irano-Turanian populations of C. foetida subsp. rhoeadiflolia in Turkey were performed. The cytogenetic characteristics of the populations using multivariate analyses (cluster analysis, principal components analysis) were evaluated in a cytogeographic context. Two main groups are found in C. foetida subsp. rhoeadiflolia based on cytogenetic characteristics among populations based on distribution pattern. The significant differences among populations mainly concern the long length of chromosome, centromeric index, and genome size. The ecological and evolutionary value of cytogenetic data are discussed within the framework of the results obtained.
Juncus L. (Juncaceae) is a genus of annual and perennial herbs composed of approximately 310 species distributed worldwide, but more rarely found in the tropics. Despite an increasing number of karyological studies in Juncaceae, reports on chromosome numbers in Korean Juncus taxa have been scarce owing to the small chromosome size. Here, we present detailed information on chromosome numbers obtained from 36 individuals of 10 Korean Juncus taxa. Chromosome numbers of eight taxa (J. diastrophanthus, J. prismatocarpus subsp. leschenaultii, J. krameri, J. papillosus, J. wallichianus, J. gracillimus, J. fauriei, and J. setchuensis) are reported for the first time. All studied taxa have different chromosome numbers and ploidy variations (2n=30, 60, and 80) with small chromosomes. These ploidy level variations are of no systematic relevance in Korean Juncus taxa; however, this variation in chromosome number might provide additional evidence for the importance of morphological diversification via polyploidization including both auto- and allopolyploidization.
Syzygium laetum (Myrtaceae) is an endemic species of Western Ghats. The karyomorphology is reported for the first time with mitotic chromosome number 2n=22. The karyotype formula is 2n=22=18m+4sm. The karyotype is a 2A type of the Stebbins category.
Longan is one of the most economically important fruits of Asian countries belonging to the family Sapindaceae. Essentially, there is a lack of fundamental karyological data on different cultivars in longan although the whole genome of longan has been successfully sequenced. This study is the first to report the chromosome numbers and karyotypes of nine cultivars of the genus Dimocarpus cultivated widely in the northern regions of Thailand. These cultivars are Chompoo, Haew, Phuangthong, Thao, Jumbo, Phuen-Mueang, Pumateenkong, Chuliang (China), Kohala (America), and one of them (Thao, Dimocarpus obtusus, Lithanatudom & Chaowasku, comb. et stat. nov.) is considered as a rare species found in Thailand. The somatic chromosome number of cells derived from the root tip collected from the air layering branch of all cultivars was determined as 2n=2x=30. All cultivars showed a predominance of metacentric chromosomes in each karyotype indicating their symmetric nature. The karyotype of these cultivars was placed into categories 1B and 2B based on Stebbins classification. In addition, we analyzed the scatter diagrams of asymmetry indices, UPGMA dendrogram with fruit morphology, and PCoA graph together with the karyotypic relationship, and overall, the results revealed that all cultivars of the genus Dimocarpus examined can be divided into two major groups.
The present study reports the chromosome number and meiotic behavior including microsporogenesis of Actaea kashmiriana J. Compton and its relation with pollen fertility and seed set. The species showed a chromosome count of 2n=4x=32 and meiotic chromosomal irregularities such as chromatin stickiness, cytomixis, laggard formation, chromosomal bridges, micronuclei and polysporads. B-chromosomes were also observed in this species. Due to these meiotic irregularities, reduced pollen fertility was observed in the range of 85–87%, and the seed set was also significantly reduced to 67.16 to 70.45%.
Chromosome numbers of six Strobilanthes (Acanthaceae) species from China have been reported for the first time: S. compacta (2n=30), S. longzhouensis (2n=30), S. reptans (2n=30), S. bantonensis (2n=32), S. hongii (2n=32) and S. retusa (2n=32). Based on reports at present, x=15 and x=16 are assumed to be the main basic chromosome numbers of Strobilanthes.
The chromosome numbers and karyotypes of five species of the genus Iris distributed in Turkey were analyzed. These taxa are I. aucheri (Baker) Sealy, I. reticulata var. reticulata M. Bieb., I. persica L., I. peshmeniana Güner & T. Hall, I. sarii Schott ex Baker. Two of them (I. sari and I. peshmeniana) are endemic in Turkey. The chromosome numbers of studied taxa were determeined as 2n=18 (I. persica), 2n=20 (I. sari), 2n=24 (I. peshmeniana and I. aucheri), and 2n=36 (I. reticulata var. reticulata). Haploid chromosome lengths varied from 53.45 µm (I. persica) to 130.78 µm (I. reticulata var. reticulata) among species. Karyotype analysis indicated that Iris taxa generally have median (m), submedian (sm), and subterminal (st) chromosomes. In addition, only I. sari has two terminal (T) chromosome pairs. The karyotype of I. peshmeniana was determined for the first time.
Previous chromosome information for Asian Begonia sect. Platycentrum with 2n=22 is restricted to 28 taxa. Here we add another 23 species to the list and reconfirm this chromosome number for nine species of sect. Platycentrum. The number of species of sect. Platycentrum with 2n=22 reported is increased to 51 taxa, covering ca. 70.8% of the 72 taxa with reported chromosome numbers in the section. Additionally, we provide the first report of karyotypes of 32 species with 2n=22 of the section. Based on the present results and previous chromosome reports for a total of 51 taxa with 2n=22, the chromosome evolution for 2n=22 in sect. Platycentrum is discussed.
The 45S and 5S rDNA loci were physically mapped by double-probe FISH on mitotic metaphase chromosomes in the six strains of F. esculentum and F. tataricum. Results showed that the chromosomes of F. esculentum and F. tataricum were very small and similar. F. esculentum and F. tataricum were diploid and the karyotype formulas of these two species were 2n=2x=16=12m+4m (SAT) and 2n=2x=16=12m+4sm (SAT), respectively. Four pairs of 45S rDNA loci on IS, IIS, IIIL, and VL, as well as two pairs of 5S rDNA loci on IL and IVS in F. esculentum, and five pairs of 45S rDNA loci on IS, IIS, IIIL, VL, and VIIS, as well as three pairs of 5S rDNA loci on IL, IVS, and VIS in F. tataricum. There are differences in 45S and 5S rDNA loci between F. esculentum and F. tataricum, suggesting they are far in phylogenies. Based on 45S and 5S rDNA loci location and karyotype characteristics of mitotic metaphase chromosomes, eight pairs of homologous chromosomes of F. esculentum and F. tataricum all can be distinguished distinctly, respectively. Traditional karyotype analysis together with rDNA FISH was a powerful approach for the studies on cytogenetics and breeding in plants, especially for these species with very small and similar chromosomes.
The chromosome numbers and karyotypes of eight species of the genus Allium distributed in Turkey were analyzed. These taxa are A. armerioides Boiss., A. orientale Boiss., A. stamineum Boiss., A. tuncelianum (Kollmann) Özhatay, B.Mathew & Şiraneci, A. subakaka Razyfard & Zarre, A. muratozelii Armağan, A. dumanii Koyuncu & Koçyiğit and A. colchicifolium Boiss. Four of them (A. armerioides, A. tuncelianum, A. muratozelii and A. dumanii) are endemic in Turkey. The chromosome numbers of all studied taxa were determined as 2n=2x=16, while A. dumanii had the chromosome number 2n=2x=16+2B. A basic number of x=8 was confirmed for all investigated species. Haploid chromosome lengths varied from 91.48 µm (A. armerioides) to 176.16 µm (A. colchicifolium) among species. Karyotype analysis indicated that Allium taxa generally are symmetrical, consisting of metacentric and submetacentric chromosome pairs. Only A. stamineum has subtelocentric chromosomes. Satellites were observed in three species; A. tuncelianum, A. subakaka, and A. armerioides. The karyotypes of A. muratozelii and A. armerioides were determined for the first time in this study.
Chromosome numbers and 2C-values of six Byblis species were determined to investigate the chromosome differentiation and genome diversity in this genus. Somatic chromosome numbers of the B. liniflora complex showed the diploid and the tetraploid numbers of 2n=16 and 32. In contrast, the chromosome number of B. gigantea, which belongs to the B. gigantea complex, displayed only the tetraploid numbers of 2n=36. The 2C DNA contents across all species studied were over a three-fold range, from the lowest value of 2C=0.64 pg in B. rorida to the highest value of 1.93 pg in B. gigantea. Since two cytotypes with different ploidy levels were seen in B. filifolia, the 2C contents of 0.70 pg and 1.81 pg were measured in the diploid (2n=2x=16) and the tetraploid (2n=4x=32), respectively. Haploid genome sizes of the tetraploid B. filifolia were, thus, 1.3 times larger than that of the diploid. The lowest haploid value of 1Cx=271 Mbp was shown in B. guehoi.
The genotoxic effects of the herbicide oxyfluorfen on the root meristem cells of Heianthus annuus L. (sunflower) were investigated. The roots were treated with 75, 150, and 300 ppm concentrations of oxyfluorfen for 12 and 24 h. The different genetic endpoints such as the mitotic index (MI), chromosome aberrations (CA), and micronuclei (MN) were analyzed in both control and test groups. The oxyfluorfen showed a marked mitodepressive action on mitosis. Additionally, MN were observed in interphase cells. The types of chromosome aberrations included disturbed prophase, c-mitosis, stickiness, laggards, and chromatid bridges. A pronounced toxic effect was observed at all concentrations applied. The herbicide oxyfluorfen may have genotoxic and clastogenic effects on sunflowers.
Coleus scutellarioides (L.) Benth. is a very popular ornamental plant with attractive colorful foliage and also has several medicinal properties. A detailed cytogenetical study was conducted in the ‘Red Trailing Queen’ horticultural form of this species. Hitherto, elaborate cytogenetic studies in this species received less attention and all of the previous studies on chromosomes are decades old. Thus, a reassessment and detailed cytogenetic study of this species are necessary. The karyotype study revealed that somatic cells contain 2n=48 small chromosomes, classified into metacentric to submetacentric. Meiotic chromosomes stained with acetocarmine and 4′,6-diamidino-2-phenylindole (DAPI) revealed the occurrence of univalent, bivalent, and multivalent associations of chromosomes along with secondary associations. The result confirms the allopolyploid origin of this plant. Meiotic irregularities like laggard chromosomes and multipolarity movement have also been found. In addition to that, variation in the chromosome numbers within pollen mother cells (PMCs) has been observed frequently. Pollen viability has been determined by fluorescein diacetate (FDA) and found to be very low. Rosmarinic acid (RA) is a natural polyphenol utilized as an anti-microbial, immunomodulatory, anti-diabetic, anti-allergic, anti-inflammatory, hepato-protectant, and renal-protectant agent. The RA content has been quantified through high-performance liquid chromatography (HPLC) to find out the medicinal efficacy. The present investigation on detailed cytogenetics study along with the pollen viability will be beneficial in the breeding program and accordingly useful in further improvement of this ornamental medicinal plant.