Bioactive properties of Sanguisorba minor L. cultivated in central Greece under different fertilization regimes.

In this study, the chemical characterization and bioactive properties of S. minor cultivated under different fertilization rates (control, half rate and full rate) were evaluated. Twenty-two phenolic compounds were identified, including five phenolic acids, seven flavonoids and ten tannins. Hydrolysable tannins were prevalent, namely Sanguiin H-10, especially in leaves without fertilization (control). Roots of full-rate fertilizer (660 Kg/ha) presented the highest flavonoid content, mainly catechin and its isomers, whereas half-rate fertilizer (330 Kg/ha), presented the highest content of total phenolic compounds, due to the higher amount of ellagitannins (lambertianin C: 84 ± 1 mg/g of dry extract). Antimicrobial activities were also promising, especially against Salmonella typhimurium (MBC = 0.44 mg/mL). Moreover, root samples revealed activity against all tested cell lines regardless of fertilization rate, whereas leaves were effective only against HeLa cell line. In conclusion, S. minor could be a source of natural bioactive compounds, while fertilization could increase phenolic compounds content.

Chemical composition and bioactive properties of Sanguisorba minor Scop. under Mediterranean growing conditions.

Sanguisorba minor Scop. is a perennial plant native to the Mediterranean region which exhibits several medicinal activities. In the present study, plant growth, chemical composition, and antitumor and antimicrobial properties of S. minor plants were evaluated under different growing conditions. In particular, plants were grown on different substrates, namely (A) peat, (B) peat : perlite (1 : 1) and (C) peat : perlite (2 : 1). The dry weight of the aerial parts and roots was higher for the peat treatment (A), whereas plant growth was severely affected in the peat : perlite (1 : 1) treatment (B). The major detected sugars were fructose and glucose, while the peat : perlite (2 : 1) treatment resulted in a significant increase of α-tocopherol, glucose and total sugars content, especially in the aerial parts. Oxalic acid and citric acid were the major organic acids detected, with a varied effect of growth substrate on organic acid profile. Growth substrate and plant part also had a significant effect on fatty acid composition, especially on linoleic acid and α-linolenic acid content which was higher in the peat : perlite (1 : 1) treatment in both aerial parts and roots. An impact on the composition of phenolic compounds was also observed, where the plants grown on peat : perlite (2 : 1) and peat : perlite (1 : 1) substrates had the highest content of individual and total phenolic compounds in their aerial parts and roots, respectively. Moreover, roots contained significantly higher amounts of phenolic compounds than the aerial parts. Moreover, plant extracts exhibited antiproliferative activity against four tumor cell lines (HeLa, HepG2, MCF-7 and NCI-H460) and a primary culture of porcine liver cells (PLP2), as well as significant antimicrobial properties. In conclusion, S. minor presented significant bioactive properties, while growth substrates affected the nutritional value, chemical composition, antitumor and antimicrobial properties of the species which could be probably attributed to the higher phenolic compound content and different compositions of phenolic compounds. Therefore, although the species is commonly found in the Mediterranean region, it is underexploited yet and its plant tissues could be a potential source of natural bioactive compounds with further use in pharmaceutical and medicinal applications.

A biotrophic fungal infection of the great burnet Sanguisorba officinalis indirectly affects caterpillar performance of the endangered scarce large blue butterfly Phengaris teleius.

Interactions between ecological communities of herbivores and microbes are commonly mediated by a shared plant. A tripartite interaction between a pathogenic fungus-host plant-herbivorous insect is an example of such mutual influences. In such a system a fungal pathogen commonly has a negative influence on the morphology and biochemistry of the host plant, with consequences for insect herbivore performance. Here we studied whether the biotrophic fungus Podosphaera ferruginea, attacking the great burnet Sanguisorba officinalis, affects caterpillar performance of the endangered scarce large blue butterfly Phengaris teleius. Our results showed that the pathogenic fungus affected the number and size of inflorescences produced by food-plants and, more importantly, had indirect, plant-mediated effects on the abundance, body mass and immune response of caterpillars. Specifically, we found the relationship between caterpillar abundance and variability in inflorescence size on a plant to be positive among healthy food-plants, and negative among infected food-plants. Caterpillars that fed on healthy food-plants were smaller than those that fed on infected food-plants in one studied season, while there was no such difference in the other season. We observed the relationship between caterpillar immune response and the proportion of infected great burnets within a habitat patch to be positive when caterpillars fed on healthy food-plants, and negative when caterpillars fed on infected food-plants. Our results suggest that this biotrophic fungal infection of the great burnet may impose a significant indirect influence on P. teleius caterpillar performance with potential consequences for the population dynamics and structure of this endangered butterfly.

Flooding tolerance of four floodplain meadow species depends on age.

Numerous restoration campaigns focused on re-establishing species-rich floodplain meadows of Central Europe, whose species composition is essentially controlled by regular flooding. Climate change predictions expect strong alterations on the discharge regime of Europe's large rivers with little-known consequences on floodplain meadow plants. In this study, we aim to determine the effects of flooding on seedlings of different ages of four typical flood meadow species. To this end, we flooded seedlings of two familial pairs of flood meadow species of wetter and dryer microhabitats for 2 weeks each, starting 2, 4, 6, and 8 weeks after seedling germination, respectively. We show that a 2-week-flooding treatment had a negative effect on performance of seedlings younger than 6 weeks. Summer floods with high floodwater temperatures may have especially detrimental effects on seedlings, which is corroborated by previous findings. As expected, the plants from wet floodplain meadow microhabitats coped better with the flooding treatment than those from dryer microhabitats. In conclusion, our results suggest that restoration measures may perform more successfully if seedlings of restored species are older than the critical age of about 6 weeks before a spring flooding begins. Seasonal flow patterns may influence vegetation dynamics of floodplain meadows and should, therefore, be taken into account when timing future restoration campaigns.

Seed-litter-position drives seedling establishment in grassland species under recurrent drought.

Changes in land use and climate interfere with grassland ecosystem processes. Here I experimentally investigated the combined effects of land-use change related litter cover and contrasting water supply on seedling emergence. In this context, the role of the initial relative position of seeds, i.e. seeds on top of the litter versus seeds beneath the litter in interaction with water supply has not been investigated so far. I hypothesised that facilitative effects of litter on seedling emergence occur when seeds are covered by litter and deteriorate when litter covers the ground and seeds fall on it (seeds on top of the litter). Further, I hypothesised that the importance of seed position for seedling emergence will increase under conditions of recurrent drought. I performed a controlled pot experiment on seedling emergence of three common European grassland species (Pimpinella saxifraga, Leontodon autumnalis, Sanguisorba officinalis) by experimental manipulations of litter and water availability. Seedling emergence under moist conditions showed no significant differences between each litter position compared to the control across species. In contrast, under recurrent drought, seedling emergence was significantly higher below the litter compared to seeds on top of the litter and the control (i.e. no litter). In abandoned land, seedling emergence may be limited when seeds fall on ground-covering litter. In contrast, in grasslands with regular low-intensity land use, seedling emergence may be enhanced when a moderate level of litter covers seeds at the end of the growing season. Protective mechanisms that occur with seeds positioned beneath litter are particularly important under recurrent drought.