Photosymbiosis is a symbiotic relationship between microalgae and non-photosynthetic eukaryotes. Such associations have independently evolved multiple times across a wide range of eukaryotic lineages. In some photosymbiotic relationships, photosymbionts supply photosynthetic products to the host, and, on the other hand, host organisms supply some nutrients. Considering these trophic interactions, photosymbiosis appears to be mutualistic, but the balance between benefits and costs is highly dependent on environmental conditions. In this article, we focus on photosymbioses in green algae, which show particularly high diversity in both symbiont and host species, and discuss how these symbiotic relationships affect the fitness of symbionts and their hosts.

Tripleurospermum hygrophilum is a threatened rare endemic species in Türkiye. In this work, an effective in vitro propagation protocol was developed for T. hygrophilum using in vitro techniques. Nodal explants were used to test in vitro shoot induction in Murashige–Skoog (MS) medium supplemented with several combinations of cytokinins and auxins. The highest number of shoots (2.90±0.55) among all the media was obtained from MS medium supplemented 0.25 mg L⁻¹ 6-Benzylaminopurine+0.1 mg L⁻¹ Indol-3-butyric acid. Rooting was observed in all auxin concentrations studied, while the highest number of roots (15.85±2.87) was found in MS medium containing 0.25 mg L⁻¹ 1-Naphthaleneacetic acid (NAA). The survival rate of the plants transferred to the external environment was found to be 98%. No changes in chromosome number (2n=2x=18) and genome size between regenerants and mother plants in natural population were detected. This in vitro propagation protocol developed herein can be used as conservation activites of the threatened endemic species of T. hygrophilum.

The genus Hoplias (trahiras) represents a species-rich group of controversial taxonomy in the family Erythrinidae. Even though cytogenetic analyses have been useful to discriminate cryptic fish species, most chromosomal data in Erythrinidae are focused on Hoplias malabaricus (common trahira), considered a species complex based on the presence of reproductively isolated karyomorphs. In turn, the giant trahiras (Hoplias gr. lacerdae and H. aimara complexes) seem to be more cytogenetically conserved even though there are few karyotypic reports in this group. In order to increase the chromosomal information in the giant trahiras, we provided the first cytogenetic characterization in a population of H. brasiliensis from an isolated river basin in Northeastern Brazil. We confirmed the general karyotype trend observed in this fish group, i.e., a diploid number (2n) of 50 distributed into 20 metacentric (m) and 30 submetacentric (sm) chromosomes, pericentromeric heterochromatin segments and active nucleolar organizer regions (Ag-NORs) at interstitial region on long arms of a sm pair. On the other hand, heteromorphic GC-rich (CMA₃⁺) sites were observed at the pericentromeric region of up to 10 chromosomal pairs in H. brasiliensis, diverging from the usual pattern reported in other populations and species of giant trahiras. The present findings indicate that, in spite of the apparent chromosomal conservativeness in this fish group, some genomic regions have undergone distinct evolutionary pathways, even within a same nominal taxon. Therefore, the utilization of refined analyses of chromosomal microstructure is recommended as a powerful tool to resolve the taxonomic uncertainties in giant trahiras.

Drosophila ananassae males have a diploid chromosome number of 2n=8. During the first meiotic division, the X–Y and 4th chromosomes pair to form a stable heterologous chromosome association that ensures normal chromosome segregation. The pairing sites have been extensively studied in D. melanogaster; however, the genetic controlling of the pairing is elusive. This study aimed to identify the gene controlling the X–Y pairing in D. ananassae. In the somatic cell division of the L8 strain of D. ananassae obtained from Sri Lanka, numerical variation in the number of Y and the chromosome 4 was observed among individuals. Five chromosomal types (XX44, XXY44, XXYY44, XXY444, and XXY4) were observed in the females and four (XY44, XO44, XYY44, and XY444) in the males. The chromosomal variation in the L8 strain was attributed to chromosome non-disjunction, resulting from an incomplete pairing of the X and Y chromosomes during male meiosis. The genetic and cytological analyses revealed a major gene controlling to X–Y paring on the right arm of the chromosome 2 in D. ananassae.

Clerodendrum indicum (L.) Kuntze. (Family Lamiaceae, common name: bamunhati) is a medicinal plant traditionally used for various therapeutic purposes. This study aimed to evaluate the antimitotic and cytotoxic effects of leaf aqueous extract of C. indicum (LAECi) in Allium cepa root tip cells. Root tips of A. cepa were treated with varying concentrations up to 8 mg/mL of LAECi for 2 to 48 h and root growth retardation, mitotic index (MI) reduction, and the occurrence of cellular abnormalities such as hyperchromasia, nuclear lesion, nuclear erosion, and giant cells were analyzed. The results showed that LAECi induced a concentration- and time-dependent root growth retardation, MI reduction, and the formation of diverse cellular abnormalities. Thus, this study explores the antimitotic and cytotoxic effects of LAECi on A. cepa root tip cells.

The studies on meiotic behavior, pollen viability, and seed set are important for devising conservation strategies for a particular plant species. The presence of meiotic bottlenecks directly influences the reproductive success of a plant species. The present study elaborates on chromosome number, male meiotic behavior, pollen viability, and seed set in six populations of Gloriosa superba, an important medicinal plant. The chromosome count recorded across all these populations was predominantly 2n=2x=22; however, anomalies in the form of laggards, inter-chromosomal connections, and precocious separation of bivalents were observed. In one of the populations, synizetic knot stage and inter-chromosomal connections were seen. At anaphase I, along with the normal segregation of 11 : 11 chromosomes, irregular segregations of 9 : 8, 11 : 9, 9 : 9, and 10 : 10 were also recorded. Both fruit and seed set percentages were very low for the species. We speculate that meiotic abnormalities are one of the reasons contributing to low reproductive output in Gloriosa superba.

Male sterility and large floral traits are among the main breeding goals of ornamental plants. Both traits are controlled by jasmonic acid. Therefore, genetic modifications in the jasmonic acid biosynthesis pathway are expected to alter these traits. In the ornamental plant torenia (Torenia fournieri), a knockout mutant of the torenia ortholog of Arabidopsis thaliana OPR3 (TfOPR3), which is involved in the jasmonic acid biosynthesis pathway in A. thaliana, was produced using CRISPR/Cas9. The Tfopr3 exhibited reduced pollen viability, seed production, and germination. The whole petal size of Tfopr3 plants showed no change, whereas the petal cell size exhibited regions with enlarged and reduced cells. In addition, the numbers of petals, stamens, and pistils were comparable to those in the wild-type plants. These results suggest that the disruption of OPR3 orthologs may partially induce male sterility without changing floral phenotypes.

The family Schisandraceae comprises approximately 23 species across three genera worldwide. On the Korean Peninsula, the two species of Schisandra, S. chinensis, S. repanda, and the species of Kadsura japonica occur. Although many pharmacological studies have been conducted on S. chinensis, cytological studies remain limited. Thus, we conducted a cytogenetic study to examine the chromosome morphology and the locations of rDNA signals. Chromosome slides were prepared from the root tips of these three species to determine chromosome numbers. Additionally, fluorescence in situ hybridization was performed using 5S rDNA and 45S rDNA. All three species had a chromosome number of 2n=28. Each species exhibited one pair of the 5S rDNA and one pair of 45S rDNA signals. Unlike S. chinensis and S. repanda, K. japonica possessed a pair of satellite chromosomes. The 5S rDNA signal was consistently observed on chromosome 5 in all three species. In contrast, the 45S rDNA signal was located on chromosome 7 in S. chinensis, but on chromosome 12 in S. repanda and K. japonica. The presence of the SAT chromosome can distinguish Kadsura from Schisandra. Furthermore, the position of the 45S rDNA signal could be used to differentiate between S. chinensis and S. repanda. The total chromosome number (2n=28) and the presence of a 5S rDNA signal on chromosome 5 are thus considered symplesiomorphies in the chromosomal evolution of the Schisandraceae. The SAT chromosome of K. japonica is considered autapomorphic. In addition, the differing locations of 45S rDNA signals between the two Schisandra species suggest that Kadsura may be more primitive. Among Schisandra, species with a 45S rDNA signal on chromosome 7 are considered advanced. Thus, it can be inferred that chromosomes evolved to become shorter in length and lost the SAT chromosomes in Schisandraceae. Our study contributes to a better understanding of the evolutionary relationships within this family.