New Techniques for Seed Shape Description in Silene Species

Seed shape in Silene species is often described by means of adjectives such as reniform, globose, and orbicular, but the application of seed shape for species classification requires quantification. A method for the description and quantification of seed shape consists in the comparison with geometric models. Geometric models based on mathematical equations were applied to characterize the general morphology of the seeds in 21 species of Silene. In addition to the previously described four models (M1 is the cardioid, and M2 to M4 are figures derived from it), we present four new geometric models (model 5–8). Models 5 and 6 are open cardioids that resemble M3, quite different from the flat models, M2 and M4. Models 7 and 8 were applied to those species not covered by models 2 to 6. Morphological measures were obtained to describe and characterize the dorsal view of the seeds. The analyses done on dorsal views revealed a notable morphological diversity and four groups were identified. A correlation was found between roundness of dorsal view and the geometric models based on lateral views, such that some of the groups defined by seed roundness are also characterized by the similarity to particular models. The usefulness of new morphological tools of seed morphology to taxonomy is discussed.

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.

Seed Morphology in Silene Based on Geometric Models

Seed description in morphology is often based on adjectives such as “spherical”, “globular”, or “reniform”, but this does not provide a quantitative method. A new morphological approach based on the comparison of seed images with geometric models provides a seed description in Silene species on a quantitative basis. The novelty of the proposed method is based in the comparison of the seed images with geometric models according to a cardioid shape. The J index is a measurement that indicates the seed percentage of similarity with a cardioid or cardioid-derived figures used as models. The seeds of Silene species have high values of similarity with the cardioid and cardioid-derived models (J index superior to 90). The comparison with different figures allows species description and differentiation. The method is applied here to seeds of 21 species and models are proposed for some of them including S. diclinis, an endangered species. The method is discussed in the context of previous comparison with the measures used in traditional morphometric analysis. The similarity of seed images with geometric figures opens a new perspective for the automatized taxonomical evaluation of samples linking seed morphology to functional traits in endangered Silene species.

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.

Ethyl Methanesulfonate and Caffeine Mutagenetic Treatment to Four Ornamental Silene Species

Mutagenesis breeding for horticultural crops is valuable not only for creating new cultivars, but also expanding the genetic pool for hybridization. Four Silene species were subjected to ethyl methanesulfonate (EMS) and/or caffeine mutagenesis to obtain valuable ornamental traits and to test the effects of different mutagens and combinations. Species responded differently to the mutagens. Generally, caffeine plus EMS treatments had a greater effect on mutation rate than either treatment applied alone. Caffeine alone was found to enhance seed vigor of S. floscuculi. Caffeine as a plant mutagen should be further investigated to determine the most efficient concentration as well as effects on other plant species, as several desirable mutants were obtained with leaf variegation.