Disentangling Relationships among the Alpine Species of Luzula Sect. Luzula (Juncaceae) in the Eastern Alps.

Polyploidisation, agmatoploidy and symploidy have driven the diversification of Luzula sect. Luzula. Several morphologically very similar species with different karyotypes have evolved, but their evolutionary origins and relationships are unknown. In this study, we used a combination of relative genome size and karyotype estimations as well amplified fragment length polymorphism (AFLP) fingerprinting to investigate the relationships among predominately (sub)alpine Luzula alpina, L. exspectata, L multiflora and L. sudetica in the Eastern Alps, including also some samples of L. campestris and L. taurica as outgroup. Our study revealed common co-occurrence of two or three different ploidies (di-, tetra- and hexaploids) at the same localities, and thus also common co-occurrence of different species, of which L. sudetica was morphologically, ecologically and genetically most divergent. Whereas agmatoploid L. exspectata likely originated only once from the Balkan L. taurica, and hexaploid L. multiflora once from tetraploid L. multiflora, the AFLP data suggest multiple origins of tetraploid L. multiflora, from which partly agmatoploid individuals of L. alpina likely originated recurrently by partial fragmentation of the chromosomes. In contrast to common recurrent formation of polyploids in flowering plants, populations of agmatoploids resulting by fission of complete chromosome sets appear to have single origins, whereas partial agmatoploids are formed recurrently. Whether this is a general pattern in Luzula sect. Luzula, and whether segregation of ecological niches supports the frequent co-occurrence of closely related cytotypes in mixed populations, remains the subject of ongoing research.

Genome Size of Life Forms of Araceae-A New Piece in the C-Value Puzzle.

The genome size of an organism is an important trait that has predictive values applicable to various scientific fields, including ecology. The main source of plant C-values is the Plant DNA C-values database of the Royal Botanic Gardens Kew, which currently contains 12,273 estimates. However, it covers only 2.9% of known angiosperm species and has gaps in the life form and geographic distribution of plants. Only 4.5% of C-value estimates come from researchers in Central and South America. This study provides 41 new C-values for the aroid family (Araceae), collected in the Piedras Blancas National Park area in southern Costa Rica, including terrestrial, epiphytic and aquatic life forms. Data from our study are combined with C-value entries in the RBGK database for Araceae. The analysis reveals a wider range of C-values for terrestrial aroids, consistent with other terrestrial plants, a trend toward slightly lower C-values for epiphytic forms, which is more consistent for obligate epiphytes, and comparatively low C-values for aquatic aroids.

Supercritical CO2 Plant Extracts Show Antifungal Activities against Crop-Borne Fungi.

Fungal infections of cultivated food crops result in extensive losses of crops at the global level, while resistance to antifungal agents continues to grow. Supercritical fluid extraction using CO2 (SFE-CO2) has gained attention as an environmentally well-accepted extraction method, as CO2 is a non-toxic, inert and available solvent, and the extracts obtained are, chemically, of greater or different complexities compared to those of conventional extracts. The SFE-CO2 extracts of Achillea millefolium, Calendula officinalis, Chamomilla recutita, Helichrysum arenarium, Humulus lupulus, Taraxacum officinale, Juniperus communis, Hypericum perforatum, Nepeta cataria, Crataegus sp. and Sambucus nigra were studied in terms of their compositions and antifungal activities against the wheat- and buckwheat-borne fungi Alternaria alternata, Epicoccum nigrum, Botrytis cinerea, Fusarium oxysporum and Fusarium poae. The C. recutita and H. arenarium extracts were the most efficacious, and these inhibited the growth of most of the fungi by 80% to 100%. Among the fungal species, B. cinerea was the most susceptible to the treatments with the SFE-CO2 extracts, while Fusarium spp. were the least. This study shows that some of these SFE-CO2 extracts have promising potential for use as antifungal agents for selected crop-borne fungi.

Root growth inhibition and ultrastructural changes in radish root tips after treatment with aqueous extracts of Fallopia japonica and F. ×bohemica rhizomes.

Allelopathic compounds released by invasive alien plants can suppress the growth of plants in their vicinity. The aim of this study was to investigate changes in tissue and cell structure in roots of radish seedlings treated with 10% aqueous extracts of rhizomes from the invasive knotweeds Fallopia japonica and F. ×bohemica. After 7 days of growth without and with aqueous extracts from these rhizomes, the anatomical and ultrastructural changes in the radish seedling roots were analyzed with light and transmission electron microscopy, and hydrogen peroxide was localized with diaminobenzidine, to define oxidative stress. The roots of radish seedlings treated with the knotweed extracts were shorter and thicker, due to the shorter and wider shapes of their cortex cells, which were organized in more columns than the control roots. There were signs of cell damage and oxidative stress in the root cap cells, and to a lesser extent in the meristematic zone. As well as the irregularly shaped nuclei and plasma membrane detached from the cell wall, the most prominent ultrastructural effects in the root cap cells of these aqueous rhizome extracts were the ring-shaped form of the mitochondria and large endoplasmic reticulum bodies. Excessive vacuolization was seen for the cells of the root apical meristem.

The Effect of Extracts and Essential Oil from Invasive Solidago spp. and Fallopia japonica on Crop-Borne Fungi and Wheat Germination.

RESEARCH BACKGROUND: Many plant extracts and essential oils show antibacterial and antifungal activities, with potential to replace the use of synthetic fungicides. We used invasive alien plants goldenrod (Solidago spp.) and Japanese knotweed (Fallopia japonica) as source materials to determine their antifungal activities against seed-associated fungi from wheat grain (Alternaria alternata, Alternaria infectoria, Aspergillus flavus, Epicoccum nigrum and Fusarium poae). EXPERIMENTAL APPROACH: Aqueous and organic extracts (ethanol, methanol and acetone) were prepared from leaves and flowers of S. canadensis, S. gigantea and S. virgaurea, and leaves and rhizomes of F. japonica. Additionally, essential oils were distilled from Solidago flowers and leaves. The extracts and essential oils were tested as inhibitors of fungal growth in vitro. Solidago essential oils were tested also as antifungal agents for protection of wheat grain by determining its fungal infection and germination rate. RESULTS AND CONCLUSIONS: The extracts showed a wide spectrum of low to moderate antifungal activities, with those of Solidago spp. generally more effective than those of F. japonica, and organic extracts more effective than aqueous extracts. The essential oils from leaves and flowers had similar antifungal activity and whole shoots can be collected for their production. This study presents the systematic study of the composition of essential oils from flowers and leaves of three widely distributed Solidago spp. in Slovenia, with the major constituents of terpenes and terpenoids α-pinene, germacrene D and bornyl acetate. NOVELTY AND SCIENTIFIC CONTRIBUTION: The study presents the first use of Solidago spp. and Fallopia japonica extracts and essential oils against fungal strains isolated from wheat grain.

Effects of exposure to nano and bulk sized TiO2 and CuO in Lemna minor.

Nanoparticles of TiO2 and CuO are among most commonly used nanoparticles, and elevated concentrations of them are expected to be found in all environments, including aquatic. A standard growth inhibition test ISO/CD 20079 was used to determine the toxicity of nano sized and larger micro sized (bulk) particles in the concentrations of 0.1, 1, 10, 100 and 1000 µM CuO and TiO2 on common duckweed (Lemna minor L.). Both nano and bulk CuO particles caused changes in the structure and function of treated plants. The number of fronds and colonies decreased by as much as 78%, the length of roots and fronds decreased by 99% and 14%, respectively. Furthermore, photochemical efficiency was reduced by up to 35%, and the activities of antioxidative enzymes guaiacol peroxidase, ascorbate peroxidase and glutathione reductase increased by more than 240%. The altered physiological state of the CuO exposed plants was also reflected in the elevated occurrence of necrosis and bleaching in the duckweed colonies. Nano sized particles of CuO proved more phytotoxic than bulk particles, and the effects of both studied CuO sizes were concentration dependent. On the other hand, both bulk and nano sized particles of TiO2 caused no severe phytotoxic effects, there was no concentration dependence and they could be considered as non-harmful to common duckweed.

A cellular study of teosinte Zea mays subsp. parviglumis (Poaceae) caryopsis development showing several processes conserved in maize.

The evolutionary history of maize (Zea mays subsp. mays) is of general interest because of its economic and scientific importance. Here we show that many cellular traits described previously in developing caryopses of maize are also seen in its wild progenitor teosinte (Zea mays subsp. parviglumis). These features, each with a possible role in development, include (1) an early programmed cell death in the maternal placento-chalazal (P-C) layer that may lead to increased hydrolytic conductance to the developing seed; (2) accumulation of phenolics and flavonoids in the P-C layer that may be related to antimicrobial activity; (3) formation of wall ingrowths in the basal endosperm transfer layer (BETL); (4) localization of cell wall invertase in the BETL, which is attributed to the increased transport capacity of photosynthates to the sink; and (5) endoreduplication in endosperm nuclei suggested to contribute to increased gene expression and greater sink capacity of the developing seed. In maize caryopsis, these cellular traits have been previously attributed to domestication and selection for larger seed size and vigor. Given the conservation of the entire cellular program in developing teosinte caryopses described here, we suggest that these traits evolved independently of domestication and predate human selection pressure.