Silene aminiradii (Caryophyllaceae), an Interesting Alpine Plant in Iran

Botanical explorations in the alpine zone of the Shahvar and Shah Kouh Mountains from Semnan and Golestan Provinces (northeastern Iran) led to the collection of interesting specimens of the genus Silene L. (Caryophyllaceae). Taxonomic study of these plants and comparison with determined plant specimens showed that the specimens belong to an unknown species. I describe it as S. aminiradii Gholipour, belonging to section Auriculatae (Boiss.) Schischk. from northeastern Iran. The new species is compared with S. lucida Chowdhuri and S. crispans Litv. as the most similar species. Silene aminiradii is a caespitose perennial alpine gynodioecious plant with prostrate stems covered with dense, retrorsely simple hairs. The distribution, ecological features, reproductive phenology, and photos of S. aminiradii are presented.

Adaptation of the autosomal part of the genome on the presence of dioecy

We have attempted to answer the question of whether the presence of sex chromosomes in the genome can affect the evolution of the autosomal part of the genome. As a model, we used dioecious plants from the section Otites of the genus Silene. We have observed a rise in adaptive evolution in the autosomal and pseudoautosomal parts of the genome, which are associated with the evolution of dioecy. This rise is caused neither by the accumulation of sexually antagonistic genes in the pseudoautosomal region nor by the co-evolution of genes acting in mitochondria (in spite of the fact that the dioecy evolved in this case most likely from cytoplasmic male sterility). Thus, this rise in the amount of positively selected codons is most likely caused by the adaptive evolution of genes involved in the specialization of the autosomal part of the genome on the dioecy as described in sex-allocation theory.

Rapid sequence evolution is associated with genetic incompatibilities in the plastid Clp complex

The plastid caseinolytic protease (Clp) complex plays essential roles in maintaining protein homeostasis and comprises both plastid-encoded and nuclear-encoded subunits. Despite the Clp complex being retained across green plants with highly conserved protein sequences in most species, examples of extremely accelerated amino acid substitution rates have been identified in numerous angiosperms. The causes of these accelerations have been the subject of extensive speculation but still remain unclear. To distinguish among prevailing hypotheses and begin to understand the functional consequences of rapid sequence divergence in Clp subunits, we used plastome transformation to replace the native clpP1 gene in tobacco (Nicotiana tabacum) with counterparts from another angiosperm genus (Silene) that exhibits a wide range in rates of Clp protein sequence evolution. We found that antibiotic-mediated selection could drive a transgenic clpP1 replacement from a slowly evolving donor species (S. latifolia) to homoplasmy but that clpP1 copies from Silene species with accelerated evolutionary rates remained heteroplasmic, meaning that they could not functionally replace the essential tobacco clpP1 gene. These results suggest that observed cases of rapid Clp sequence evolution are a source of epistatic incompatibilities that must be ameliorated by coevolutionary responses between plastid and nuclear subunits.

Taxonomic Revisiting and Phylogenetic Placement of Two Endangered Plant Species: Silene leucophylla Boiss. and Silene schimperiana Boiss. (Caryophyllaceae)

The genus Silene L. is one of the largest genera in Caryophyllaceae, and is distributed in the Northern Hemisphere and South America. The endemic species Silene leucophylla and the near-endemic S. schimperiana are native to the Sinai Peninsula, Egypt. They have reduced population size and are endangered on national and international scales. These two species have typically been disregarded in most studies of the genus Silene. This research integrates the Scanning Electron Microscope (SEM), species micromorphology, and the phylogenetic analysis of four DNA markers: ITS, matK, rbcL and psb-A/trn-H. Trichomes were observed on the stem of Silene leucophylla, while the S. schimperiana has a glabrous stem. Irregular epicuticle platelets with sinuate margin were found in S. schimperiana. Oblong, bone-shaped, and irregularly arranged epidermal cells were present on the leaf of S. leucophylla, while Silene schimperiana leaf has “tetra-, penta-, hexa-, and polygonal” epidermal cells. Silene leucophylla and S. schimperiana have amphistomatic stomata. The Bayesian phylogenetic analysis of each marker individually or in combination represented the first phylogenetic study to reveal the generic and sectional classification of S. leucophylla and S. schimperiana. Two Silene complexes are proposed based on morphological and phylogenetic data. The Leucophylla complex was allied to section Siphonomorpha and the Schimperiana complex was related to section Sclerocalycinae. However, these two complexes need further investigation and more exhaustive sampling to infer their complex phylogenetic relationships.

Dioecy Is Associated with High Genetic Diversity and Adaptation Rates in the Plant Genus Silene

About 15,000 angiosperm species (∼6%) have separate sexes, a phenomenon known as dioecy. Why dioecious taxa are so rare is still an open question. Early work reported lower species richness in dioecious compared with nondioecious sister clades, raising the hypothesis that dioecy may be an evolutionary dead-end. This hypothesis has been recently challenged by macroevolutionary analyses that detected no or even positive effect of dioecy on diversification. However, the possible genetic consequences of dioecy at the population level, which could drive the long-term fate of dioecious lineages, have not been tested so far. Here, we used a population genomics approach in the Silene genus to look for possible effects of dioecy, especially for potential evidence of evolutionary handicaps of dioecy underlying the dead-end hypothesis. We collected individual-based RNA-seq data from several populations in 13 closely related species with different sexual systems: seven dioecious, three hermaphroditic, and three gynodioecious species. We show that dioecy is associated with increased genetic diversity, as well as higher selection efficacy both against deleterious mutations and for beneficial mutations. The results hold after controlling for phylogenetic inertia, differences in species census population sizes and geographic ranges. We conclude that dioecious Silene species neither show signs of increased mutational load nor genetic evidence for extinction risk. We discuss these observations in the light of the possible demographic differences between dioecious and self-compatible hermaphroditic species and how this could be related to alternatives to the dead-end hypothesis to explain the rarity of dioecy.

Antioxidant Capacity of Three Silene Extracts Obtained by Ultrasonication-Assisted Extraction (UAE)

Many plants with high antioxidant activity are great of significant in the pharmaceutical and cosmetic industries. Oxidative stress plays a major part in the development of many diseases including cancer, which is known imbalance free radicals and antioxidants. Herein, new natural antioxidant compounds have great interest in the scientific research. The genus Silene is a major group in the Caryophyllaceae family. In Turkey, Silene species have been used for several medicinal purposes such as skin softening, asthma, bronchitis. In our study, the antioxidant capacity of three Silene species (S. conoidea, S. dichotoma and S. italica) were evaluated by different in vitro assays, including free radical scavenging, reducing power, metal chelating, and phosphomolybdenum. In addition, total phenolic and flavonoid contents were analyzed spectrophotometrically. The water extracts contained higher total phenolic content than ethyl acetate extracts. All extracts showed antioxidant capacity. This data indicated that Silene species could potentially be used as antioxidant sources in pharmaceutical and cosmetic areas.

C-/O-GLYCOSYL FLAVONES OF SILENE ITALICA

Chemical research of Silene genus focused on the study of terpene compounds including ecdysteroids and triterpenoids, to the detriment of other classes of compounds. One of these poorly estimated group of substances are flavonoids, namely C-/O-glycosyl flavones, widely represented within the family Caryophyllaceae. Early studies revealed the presence of some C-glycosyl flavones (Zemtsova, Dzhumyrko, 1976; Darmogray, 1977), but a detailed study of the flavonoids was not conducted. Application of high performance chromatography with diode-array detection and electrospray ionization mass-spectrometry detection (HPLC-DAD-ESI-MS) allowed to found 14 flavonoids, which are C-, O- and C,O-glycosyl flavones in the aerial part of S. italica of Georgia origin. Ten components were discovered in S. italica for first time. The identified C-glycosides included monoglycosides as isoorientin, isovitexin, isoscoparin (chrysoeryol-6-C-glucoside) and diglycosides as carlinoside (luteolin-6-C-glucoside-8-C-arabinoside), schaftoside (apigenin-6-C-glucoside-8-C-arabinoside), isoschaftoside (luteolin-6-C-arabinoside-8-C-glucoside) and genkwanin-6-C-glucoside-8-C-arabinoside. Two O-glycosides, cosmosiin and cynaroside, and mixed C,O-glycosides as saponarin, isovitexin-2′′-O-arabinoside, isovitexin-6′′-O-arabinoside and O-hexosides od schaftosude and genkwanin-6-C-glucoside- 8-C-arabinoside were not previously identified in Silene genus. The known literature data (Mamadalieva et al., 2014) and the present data demonstrate the useful role of C-/O-glycosyl flavones in the systematics of the genus Silene.