Biogeographic origins of southern African Silene (Caryophyllaceae)

New cyclic glycolipids from Silene succulenta promote in vitro MCF-7 breast carcinoma cell apoptosis by cell cycle arrest and in silico mitotic Mps1/TTK inhibition

In vitro anticancer screening of Silene succulenta Forssk. aerial parts (Caryophyllaceae) showed that the n-hexane fraction was a highly effective fraction against breast carcinoma cell lines (MCF-7) with IC50 = 15.5 μg mL-1. The bioactive-guided approach led to the isolation of two new cyclic glucolipids from the n-hexane fraction, identified as a 1,2'-cyclic ester of 11-oxy-(6'-O-acetyl-β-d-glucopyranosyl) behenic acid (1) as a C-11 epimeric mixture and 11(R)-oxy-(β-d-glucopyranosyl)-1,2'-cyclic ester of behenic acid (2). An in vitro cytotoxicity study showed the potential suppression of MCF-7 cells with IC50 values of 11.7 ± 0.04 and 6.6 ± 0.01 μg mL-1 for compounds 1 and 2, respectively, compared to doxorubicin (IC50 = 3.83 ± 0.01 μg mL-1). Accordingly, only cell cycle tracking for the most active compound (2) was assessed. The cell cycle investigation showed that compound 2 altered the cell cycle at G0/G1, S, and G2/M phases in MCF-7 treated cells. In addition, its powerful apoptotic ability resulted in a significant increase in the early and late stages of apoptosis. Moreover, molecular docking analysis, which was performed against the anticancer mitotic (or spindle assembly) checkpoint target Mps1 kinase, showed that the two new cyclic glycolipids (1 and 2) possess high binding affinity of -7.7 and - 7.6 kcal mol-1, respectively, compared to its ATP ligand. Overall, this report emphasizes that natural cyclic glycolipids can be used as potential antitumour breast cancer agents.

The role of hybrid seed inviability in angiosperm speciation

Understanding which reproductive barriers contribute to speciation is essential to understanding the diversity of life on earth. Several contemporary examples of strong hybrid seed inviability (HSI) between recently diverged species suggest that HSI may play a fundamental role in plant speciation. Yet, a broader synthesis of HSI is needed to clarify its role in diversification. Here, I review the incidence and evolution of HSI. Hybrid seed inviability is common and evolves rapidly, suggesting that it may play an important role early in speciation. The developmental mechanisms that underlie HSI involve similar developmental trajectories in endosperm, even between evolutionarily deeply diverged incidents of HSI. In hybrid endosperm, HSI is often accompanied by whole-scale gene misexpression, including misexpression of imprinted genes which have a key role in endosperm development. I explore how an evolutionary perspective can clarify the repeated and rapid evolution of HSI. In particular, I evaluate the evidence for conflict between maternal and paternal interests in resource allocation to offspring (i.e., parental conflict). I highlight that parental conflict theory generates explicit predictions regarding the expected hybrid phenotypes and genes responsible for HSI. While much phenotypic evidence supports a role of parental conflict in the evolution of HSI, an understanding of the underlying molecular mechanisms of this barrier is essential to test parental conflict theory. Lastly, I explore what factors may influence the strength of parental conflict in natural plant populations as an explanation for why rates of HSI may differ between plant groups and the consequences of strong HSI in secondary contact.

The Outline of Seed Silhouettes: A Morphological Approach to Silene (Caryophyllaceae)

Seed morphology is an important source of information for plant taxonomy. Nevertheless, the characters under study are diverse, and a simple, unified method is lacking in the literature. A new method for the classification of seeds of the genus Silene based on optical images and image analysis has recently been described on the basis of morphological measurements of the lateral seed views. According to the outline of their silhouettes, seeds from 52 species (49 of Silene and three related species) were classified in three groups: smooth, rugose and echinate, revealing remarkable differences between these groups. This methodology has been applied here to 51 new species, making a total of 100 species of Silene analyzed so far. According to our data, a new group was described, termed papillose. The results showed morphological differences between the four mentioned seed groups, with reduced values of circularity for dorsal and lateral seed views in the papillose and echinate groups and reduced values of solidity in the papillose seeds. The method was applied to the analysis of individual as well as to average seed silhouettes and some of the differences between groups were maintained in both cases.

Relationships within Mcneillia Indicate a Complex Evolutionary History and Reveal a New Species of Minuartiella (Caryophyllaceae, Alsinoideae)

The genus Mcneillia has been recently segregated from Minuartia L. based on molecular results, also supported by morphology. However, to date, a comprehensive study on the phylogenetic relationships within this genus is lacking. In this paper, we provide a multigene phylogeny of all the species and subspecies of Mcneillia employing two nuclear and six chloroplast markers. We documented extensive gene flow between taxa, sometimes separated at specific rank. In addition, Mcneillia as currently circumscribed, is not monophyletic. In fact, Mcneillia graminifolia subsp. brachypetala, strictly endemic to Greece, truly belongs to Minuartiella, a genus otherwise limited to South-West Asia. Moreover, even after removal of this taxon, our results do not support the monophyly of the taxa included in M. graminifolia s.l., the most variable and widespread species of the genus. Further controversial subspecies of Mcneillia graminifolia, i.e., subsp. hungarica and subsp. rosanoi, are shown to deserve taxonomic recognition as separate species, whereas Mc. moraldoi is not distinct at specific rank. In addition, Mc. saxifraga subsp. tmolea is here regarded as a further distinct species. A consistent taxonomic treatment is therefore proposed with six new combinations and nomenclatural notes, providing the necessary typifications.

Long-read transcriptome and other genomic resources for the angiosperm Silene noctiflora

The angiosperm genus Silene is a model system for several traits of ecological and evolutionary significance in plants, including breeding system and sex chromosome evolution, host-pathogen interactions, invasive species biology, heavy metal tolerance, and cytonuclear interactions. Despite its importance, genomic resources for this large genus of approximately 850 species are scarce, with only one published whole-genome sequence (from the dioecious species Silene latifolia). Here, we provide genomic and transcriptomic resources for a hermaphroditic representative of this genus (S. noctiflora), including a PacBio Iso-Seq transcriptome, which uses long-read, single-molecule sequencing technology to analyze full-length mRNA transcripts. Using these data, we have assembled and annotated high-quality full-length cDNA sequences for approximately 14,126 S. noctiflora genes and 25,317 isoforms. We demonstrated the utility of these data to distinguish between recent and highly similar gene duplicates by identifying novel paralogous genes in an essential protease complex. Furthermore, we provide a draft assembly for the approximately 2.7-Gb genome of this species, which is near the upper range of genome-size values reported for diploids in this genus and threefold larger than the 0.9-Gb genome of Silene conica, another species in the same subgenus. Karyotyping confirmed that S. noctiflora is a diploid, indicating that its large genome size is not due to polyploidization. These resources should facilitate further study and development of this genus as a model in plant ecology and evolution.