Sex chromosome-based sex determination (SD) systems have evolved from autosomes in many animals and some plants. Suppression of recombination around the SD locus drives the differentiation of X/Y or Z/W pairs, often resulting in the degeneration of the Y (or W) chromosome. Despite this vulnerability, sexual reproduction remains stable through compensatory mechanisms, one of which is ‘turnover’, the replacement of one sex chromosome system by another. While ‘turnover’ is relatively rare in mammals, it occurs more frequently in fish and amphibians. Recent genomic studies have shown that ‘turnover’ also occurs in plants. In poplar and willow, the duplication and relocation of the SD gene to another autosome suggests ‘turnover’ events. In Silene latifolia, the Y chromosome retains a masculinisation gene (GSFY), whereas the X chromosome harbours a feminisation gene (SlWUS1). As the Y chromosome degenerates, GSFY may be lost. In this scenario, turnover may occur if SlWUS1 expression increases as a feminising SD gene, shifting from an XY-type SD system to an X/A-type system. Although further analysis is needed in Silene, these findings suggest that plants may have turnover mechanisms, as in animals, to compensate for the loss of sex chromosomes. Insights into plant turnover emphasise that it is not limited to animals and is a general evolutionary process common to plants and animals.

Human bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exos) have shown potential as an effective therapeutic tool for the management of colorectal cancer (CRC). Aberrant Wnt pathway activation has been established as a primary mechanism that drives CRC progression. This study aimed to evaluate the potential efficacy of BMSCs-Exos in CRC cell proliferation, migration, and invasion via modulation of the Wnt pathway in vitro. Exos were isolated from the supernatant of cultured human BMSCs and characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blotting. BMSCs-Exos were introduced to human CRC cell lines (HCT116 and SW480) to detect the effects of BMSCs-Exos on CRC cell proliferation, invasion, migration, and apoptosis by CCK-8, Transwell, and flow cytometric assays. Furthermore, the potential mechanism of BMSCs-Exos in regulating these functions of HCT116 and SW480 cells was investigated by quantitative reverse transcription-PCR (RT-qPCR) and Western blotting for the expression levels of the Wnt pathway-related genes. BMSCs-Exo treatment decreased HCT116 and SW480 cell proliferation, migration, and invasion, and potentiated apoptosis of CRC cells. Moreover, mRNA and protein expression patterns of the Wnt pathway-related genes Wnt1, Wnt2, Wnt3, and Wnt3a, as well as protein expression of nuclear β-catenin, were downregulated in HCT116 and SW480 cells after treatment with BMSCs-Exos. Conversely, the activated Wnt pathway partially offset the regulatory effects of BMSCs-Exos on HCT116 and SW480 cell malignant behaviors and nuclear β-catenin protein expression. These findings suggest that BMSCs-Exos repress the Wnt pathway with subsequent reduction of β-catenin nuclear translocation, promoting cell apoptosis and thereby attenuating proliferation, migration, and invasion of CRC cells in vitro.

Homoarginine is a toxic non-protein amino acid that occurs naturally in plants and adversely affects plant growth and development. In this study, it was aimed to investigate the effects of different externally applied L-homoarginine doses (10, 50, and 100 mM) on various physiological, cytogenetic, biochemical, and anatomical parameters of onion (Allium cepa L.) bulbs. All L-homoarginine doses caused a decrease in the physiological parameters examined (germination percentage, root length, root number, and fresh weight), a rise in chromosomal aberrations and micronucleus frequency, and a decrease in the mitotic index. L-Homoarginine applications promoted chromosomal aberrations such as cellular budding, accumulation of micronuclei, C-metaphase, chromosomal stickiness, chromatid bridges, vagrant chromosomes, unequal separation of chromosomes, and polar slip in the root meristem cells. In addition, this non-protein amino acid caused an enhancement in the free proline, catalase, superoxide dismutase, and malondialdehyde contents in the root cells of onion bulbs. Moreover, this toxic amino acid revealed some serious damage and changes such as the epidermal and cortex cell deformations, wall thickening in the cortex layer cells, accumulation of some chemical compounds in cortex layer cells, flattening of the cell nuclei, and deformation of the cell nuclei in the anatomical structure of onion roots. In summary, it was concluded that L-homoarginine is an amino acid with inhibitory effects and that the A. cepa test is a useful bioindicator for monitoring these effects.

We report the first chromosome counts for four species of Begonia sect. Platycentrum, three with 2n=44 and one with 2n=66, and reinvestigated the chromosome cytology of two species of the section with chromosome numbers of 2n=44 and 2n=60, respectively. The karyotypes of these six species are reported for the first time. Based on these karyotypes, species with 2n=44 and 2n=66 are shown to be tetraploids and hexaploid with x=11, respectively, whereas B. formosana (2n=60) is hypothesized to be an amphidiploid, likely originating from hybridization between a diploid with 2n=22 (i.e., B. longifolia or B. palmata) and a tetraploid with 2n=38, which are represented by four species endemic to Taiwan.

The chromosomal karyotype characteristics and phylogenetic relationships within 42 germplasm accessions from the genus Rosa L. sect. Chinenses were investigated through an integrative cytogenetic approach. Chromosome structural variation and evolutionary patterns were further assessed by combining karyotype clustering, a phylogenetic tree constructed based on SNPs, and fluorescence in situ hybridization (FISH) targeting ribosomal DNA (rDNA) loci. The analysis revealed that the chromosomes of sect. Chinenses are predominantly characterized by median and submedian centromeres, with low karyotype asymmetry indices, reflecting an overall conserved chromosomal architecture. Karyotype-based clustering offered partial resolution of ploidy levels and phylogenetic affinities among accessions, yet discrepancies were observed when compared with the SNP-derived phylogenetic tree, particularly in the delimitation between the ‘Ser. Chinenses’ and the ‘Ser. Odoratae.’ FISH results demonstrated that the number of 45S rDNA loci corresponded well with ploidy levels, while 5S rDNA loci were mainly localized in the centromeric regions. All accessions exhibited a collinear arrangement of 5S and 45S rDNA signals. In triploid accessions, the chromosomal locus composition mirrored that of R. chinensis var. spontanea, suggesting its potential role as a genomic donor. The combined application of karyotype analysis and rDNA-FISH proved effective in elucidating chromosomal evolutionary features within sect. Chinenses, providing valuable cytogenetic evidence for taxonomic classification and phylogenetic studies in Rosa.

Cycas rumphii Miq. (queen sago) is a dioecious gymnosperm of considerable evolutionary and ecological significance. This study provides a comprehensive cytogenetic comparison of male and female C. rumphii through integrated mitotic and meiotic analyses. Mitotic investigation revealed a uniform diploid chromosome complement (2n=22) in both sexes. Detailed karyotype assessment revealed subtle morphological distinctions, with male plants having heteromorphic sex chromosomes and females having homomorphic karyotypes. Both sexes lack satellite-bearing chromosomes; however, males bear distinct heteromorphic sex chromosome pairs, suggesting a reliable sex-linked chromosomal marker. Meiotic evaluation of male sporocytes revealed normal progression from leptotene to tetrad formation. During diakinesis, 11 ring bivalents were observed with their subsequent equatorial alignment at metaphase, followed by regular segregation at anaphase I and balanced tetrad formation, indicating the absence of meiotic irregularities. According to Stebbins’ (1971) asymmetry index, the male C. rumphii karyotype was assigned to the 2A class, showing low asymmetry, while the female counterparts fell into the 2B class, revealing moderate asymmetry, thereby reflecting a subtle intra-karyotype heterogeneity. These findings provide deeper insights into the cytogenetics of C. rumphii, elucidating the chromosomal features underlying sex determination and meiotic stability. These insights offer valuable markers for early sex identification and contribute to conservation strategies aimed at safeguarding the diversity of cycads.

Mentha L. is a valuable source for cytological investigations due to its pronounced polymorphism and diverse chromosomal races within species. Chromosome numbers have been studied in many species, but detailed karyotype analysis remains unexplored for the studied species. This study analyzed Mentha arvensis and M. viridis using aceto-orcein and DNA-based fluorochrome staining to elucidate their ploidy and karyotypic variation. The somatic chromosome formulae were 2n=6x=72m in M. arvensis and 2n=3x=36m in M. viridis. M. viridis showed comparatively larger chromosomal lengths, higher CV_CI and CV_CL values than M. arvensis, indicating greater variation in chromosomal length and centromeric dispersion. The GC-specific stain, chromomycin A₃, revealed 5 and 2 CMA^+ve chromosomes in M. arvensis and M. viridis, respectively. The AT-specific stain, 4,6-diamidino-2-phenylindole, showed 6 DAPI^+ve chromosomes in M. viridis only. This unique banding pattern found in the CMA/DAPI staining highlights the distribution of AT- and GC-rich regions.

The somatic chromosome numbers were counted in seven species of the subtribe Erantheminae from various localities in China. The chromosome numbers were determined as 2n=2x=28 in Echinacanthus lofouensis, Ec. longipes and Ec. longzhouensis, 2n=8x=88 in Eranthemum austrosinense, 2n=4x=44 in Er. pulchellum, 2n=2x=28 in Leptosiphonium venustum and 2n=2x=28 in Pararuellia glomerata. Combined with existing reports, it is inferred that x=14 may represent the original basic chromosome number for Echinacanthus and Pararuellia, and x=11 for Eranthemum. The results support the close relationship between Echinacanthus and other genera of Erantheminae. This study enriches the cytogenetic data for seven species and provides a basis for the taxonomy of four genera in terms of chromosomal characteristics.

Cytological investigations were carried out on 87 accessions of Sida species collected from the regions of North India. The study showed the occurrence of six species of Sida in the region, namely, Sida acuta, S. cordata, S. cordifolia, S. keralensis, S. mysorensis, and S. rhombifolia. S. acuta, S. cordifolia, and S. keralensis showed the presence of a gametophytic chromosome number of n=14, while S. cordata and S. mysorensis showed n=16 chromosomes. All these species were thus observed to be tetraploid based on x=7. The accessions of S. rhombifolia were observed to be diploid with n=7. The phylogenetic analysis showed the prevalence of two genetically distinct clades within the genus. The study provides novel data about the genetic status of Sida from the study area, particularly for S. keralensis.