Wasserlinsen als Nutzpflanzen

Duckweeds as crop plants Members of the plant family Lemnaceae (duckweeds) are not only interesting because they represent the smallest flowering plants; they possess also the fastest rates of producing biomass. As aquatic plants, duckweed production is not in competition with other agricultural crops that require fertile land while the cultivation of duckweeds does not contribute to further eutrophication of surface water. Instead, they can be cultivated on municipal or agricultural waste water and remove the nutrients during their propagation and growth. Duckweeds can thus be used for cleaning of waste water and the resulting biomass can be valuable starting material for animal feeds and the production of biofuels. Research focusing on these goals has begun to transfer from research laboratories to pilot plants in different parts of the world, e.g. in New Jersey and North Carolina, USA; Chengdu, P. R. China; and Armidale, Australia.     

Cytokinin-induced growth in the duckweeds <Emphasis Type="Italic">Lemna gibba</Emphasis> and <Emphasis Type="Italic">Spirodela polyrhiza</Emphasis>

Duckweeds, quick-growing aquatic plants, have been recently recognized as promising hosts for the large-scale production of recombinant proteins and as an ideal biomass feedstock for biofuel production. These possible wide-spread industrial uses of duckweeds intensified research aimed at understanding the mechanisms that control duckweed growth. Here, we describe how the hormone cytokinin affects growth. We performed a number of standard cytokinin growth- and physiological-response assays using sterile-grown colonies of Lemna gibba and Spirodela polyrhiza. Similar to land plants, cytokinin inhibited root elongation in duckweeds. Surprisingly, and in contrast to land plants, cytokinin promoted growth of aerial organs in both duckweed species, suggesting that the cytokinin growth response fundamentally differs between aquatic and land plants.     

Species interactions in three Lemnaceae species growing along a gradient of zinc pollution

Duckweeds (Lemnaceae) are increasingly studied for their potential for phytoremediation of heavy‐metal polluted water bodies. A prerequisite for metal removal, however, is the tolerance of the organism to the pollutant, e.g., the metal zinc (Zn). Duckweeds have been shown to differ in their tolerances to Zn; however, despite them most commonly co‐occurring with other species, there is a lack of research concerning the effect of species interactions on Zn tolerance. Here, we tested whether the presence of a second species influenced the growth rate of the three duckweed species Lemna minor, Lemna gibba, and Lemna turionifera. We used four different Zn concentrations in a replicated microcosm experiment under sterile conditions, either growing the species in isolation or in a two‐species mixture. The response to Zn differed between species, but all three species showed a high tolerance to Zn, with low levels of Zn even increasing the growth rates. The growth rates of the individual species were influenced by the identity of the competing species, but this was independent of the Zn concentration. Our results suggest that species interactions should be considered in future research with duckweeds and that several duckweed species have high tolerance to metal pollution, making them candidates for phytoremediation efforts.     

Sekundärstoffe – die Geheimwaffen der Pflanzen

Secondary metabolites Already 400 million years ago when land plants evolved, they probably produced secondary metabolites as means of defence against herbivores, microbes and competing plants. Secondary metabolites usually are bioactive agents, which can interfere with molecular targets in animals and microbes. Therefore, many plants and substances isolated from them can serve as valuable drugs in medicine and pharmacy. Some secondary metabolites also serve as signal compounds to attract pollinating animals and seed‐dispersing animals, but also for UV protection, as antioxidants or mobile nitrogen stores. Biology and evolution but also physiological and genetic bases of secondary metabolism are discussed in this overview.     

Gesundheit und Ernährung: Die Macht der Kultur

Health and nutrition: The power of cultural patterns Despite enormous educational efforts and widely spread common knowledge about the subject, today's nutrition as it is practiced by many consumer groups concerning health in Germany, shows great potential to be optimized. On one side this is due to a cognitive dissonance: The knowledge about a healthy nutrition is opposed to a practice that is often detrimental to health. Among other factors, the main reasons for that phenomenon can be found within psychological aspects of nutrition: Practices that are tried and tested have a stabilizing effect and lead to emotional security. On the other side nutritional systems in principle change slowly and are difficult to control, especially since food itself and communicating about it function as ideological placings, as a representation of status or are matter of distinction in a society driven by modern lifestyles. Oftentimes supposedly reasonable nutritional practices hardly show any commonalities with these realities. Furthermore people who live in Germany but who were socialized with a different cultural background tend to have conceptions of a valuable nutrition that are often contradictorily to scientific findings. That also counts for people who obtain information from internet platforms that are not scientifically oriented. There they pick up superficial knowledge, esoteric beliefs or ideology‐based hints delivered through a science‐based appearance.     

Efficient genetic transformation and CRISPR/Cas9‐mediated genome editing in Lemna aequinoctialis

The fast growth, ease of metabolic labelling and potential for feedstock and biofuels production make duckweeds not only an attractive model system for understanding plant biology, but also a potential future crop. However, current duckweed research is constrained by the lack of efficient genetic manipulation tools. Here, we report a case study on genome editing in a duckweed species, Lemna aequinoctialis, using a fast and efficient transformation and CRISPR/Cas9 tool. By optimizing currently available transformation protocols, we reduced the duration time of Agrobacterium‐mediated transformation to 5–6 weeks with a success rate of over 94%. Based on the optimized transformation protocol, we generated 15 (14.3% success rate) biallelic LaPDS mutants that showed albino phenotype using a CRISPR/Cas9 system. Investigations on CRISPR/Cas9‐mediated mutation spectrum among mutated L. aequinoctialis showed that most of mutations were short insertions and deletions. This study presents the first example of CRISPR/Cas9‐mediated genome editing in duckweeds, which will open new research avenues in using duckweeds for both basic and applied research.     

Von der Krebsschale in die Creme

From crustacean to cream Chitin is one of the most abundant biopolymers on earth and can be obtained in large quantities from shell waste from the fishing industry. However, established chemical technologies are hazardous to human health and the environment due to the use of highly acidic and alkali conditions. Microbiological fermentation and the use of enzymes for the extraction of the polymer have been proven valuable alternatives which also yield other added‐value compounds from this raw material. However, the variety of organisms and conditions used and the varying yields that are obtained make it difficult to evaluate and compare these methods for upscaling to industrial use. Nonetheless, chitin and its derivatives have shown great potential in their antimicrobial antioxidative and binding properties that find use in food technology and medicine as well as in agriculture and consumer goods. To drive the innovation forward in this field, an interdisciplinary approach joining biology and chemistry is required.     

Warum gibt es eine Waldgrenze?

Why are there alpine and polar treelines? The low temperature, high elevation or polar range limit of trees falls at a surprisingly uniform global isotherm, irrespective of whether the growing season lasts 3 or 12 month, or whether 'winter phenomena' occur or not. This potential 'life‐form' limit is predictable from climate data and is not to be confused with random, disturbance effects that may cause the local absence of trees from that boundary. The upright stature of trees exposes them to free atmospheric circulation, whereas small stature alpine plants profit from the warmer conditions near the ground, the reason why these plants can reach much higher elevations than trees. Physiologically, these plants are not more robust than trees.     

Survey of duckweed diversity in Lake Chao and total fatty acid,triacylglycerol, profiles of representative strains

Lemnaceae (duckweeds) are widely distributed aquatic flowering plants. Their high growth rate, starch content and suitability for bioremediation make them potential feedstock for biofuels. However, few natural duckweed resources have been investigated in China, and there is no information about total fatty acid (TFA) and triacylglycerol (TAG) composition of duckweeds from China. Here, the genetic diversity of a natural duckweed population collected from Lake Chao, China, was investigated using multilocus sequence typing (MLST). The 54 strains were categorised into four species in four genera, representing 12 distinct sequence types. Strains representing Lemna aequinoctialis and Spirodela polyrhiza were predominant. Interestingly, a surprisingly high degree of genetic diversification within L. aequinoctialis was observed. The four duckweed species revealed a uniform fatty acid composition, with three fatty acids, palmitic acid, linoleic acid and linolenic acid, accounting for more than 80% of the TFA. The TFA in biomass varied among species, ranging from 1.05% (of dry weight, DW) for L. punctata and S. polyrhiza to 1.62% for Wolffia globosa. The four duckweed species contained similar TAG contents, 0.02% mg·DW^?1. The fatty acid profiles of TAG were different from those of TFA, and also varied among the four species. The survey investigated the genetic diversity of duckweeds from Lake Chao, and provides an initial insight into TFA and TAG of four duckweed species, indicating that intraspecific and interspecific variations exist in the content and composition of both TFA and TAG in comparison with other studies.     

Plants as 'chemical factories' for the production of polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs) are valuable products because of their involvement in several aspects of human health. Market demand for most PUFAs is growing continually and current sources are considered insufficient for satisfying this demand; alternative sources are actively sought after. Oilseed plants can be a potential source of PUFAs if they are appropriately gene engineered. Most of the basic tools for genetic engineering of oilseed plants for giving them the ability to produce PUFAs are already developed. Here we review the prospects of genetic engineering of oilseed plants for producing some valuable long-chain polyunsaturated fatty acids. Genetic transformation for GLA production seems to be a near-term possibility, but gene engineering seems considerably more difficult for the other long-chain PUFAs. Nevertheless, with the current rapid pace of biotechnological advancement, the remaining difficulties may be surmounted in the near future.     

DNA barcoding of the <Emphasis Type="Italic">Lemnaceae</Emphasis>, a family of aquatic monocots

Background  

Members of the aquatic monocot family Lemnaceae (commonly called duckweeds) represent the smallest and fastest growing flowering plants. Their highly reduced morphology and infrequent flowering result in a dearth of characters for distinguishing between the nearly 38 species that exhibit these tiny, closely-related and often morphologically similar features within the same family of plants.     

Die facettenreiche Welt der Apocarotinoide. Farben,Düfte,Aromen und Hormone

Apocarotenoids are tailored from carotenoids by highly specific oxidative enzymes cleaving different double bonds. New chromophores can be generated, which make additional nuances of the yellow‐red color spectrum available. Colorless C13 apocarotenoids can constitute potent scent and aroma compounds. Many apocarotenoid hormone functions are well‐known (abscisic acid in plants, trisporic acid in fungi, retinoic acid in mammals). A new class of apocarotenoid plant hormones, which take part in determining shoot branching has recently been identified as strigolactones. In the biosyntheses of strigolactones and mycorrhiza‐induced C13/C14 apocarotenoids several sequential cleavage reactions occur. The knowledge about biosynthetic pathways and functions of apocarotenoids opens up new perspectives for its application in horticulture and in the control of parasitic weeds as well as in the manipulation of flower scents and fruit aromas.     

Molekulare Studien an Ameisenbäumen

Molecular systematic studies in Southeast Asian ant‐plants Myrmecophytes are plants that are permanently inhabited by ants. They provide nesting space and feed their partners, whereas the ants protect their hosts from herbivores and competitors such as climbers and lianas. The manifold relationships between tropical pioneer trees of the genus Macaranga and their partner ants of the genus Crematogaster constitute the most important and species‐rich mutualistic ant‐plant relationship of the Paleotropics. We use comparative DNA sequencing and molecular marker technologies to evaluate phylogenetic relationships among the about 30 myrmecophytic Macaranga species as well as their co‐evolution with ants. We also study the population genetics and historical biogeography of particular Macaranga species groups. Patterns of genetic diversity and differentiation in these pioneer tree species show interesting correlations with their reproductive biology and with characteristics of the increasingly fragmented pioneer habitats in the rainforests of Sundaland.     

Food or sex; pollinator–prey conflict in carnivorous plants

Carnivorous plants potentially trap their own pollinators and it has been argued that considerable spatial separation of flowers and traps has evolved to protect pollinators. We investigated flower-trap separation of Drosera and Utricularia . Short Drosera had a greater element of floral–trap separation than tall Drosera . Such a relationship is unexpected for plants whose peduncles were evolved to protect their pollinators. Utricularia can not trap pollinators but this genus still produces exceptionally long peduncles. We propose that flower-trap separation evolved because carnivorous plants are often short and need to project their flowers well above ground level to make them more attractive to pollinators.     

Linking Plant Specialization to Dependence in Interactions for Seed Set in Pollination Networks

Studies on pollination networks have provided valuable information on the number, frequency, distribution and identity of interactions between plants and pollinators. However, little is still known on the functional effect of these interactions on plant reproductive success. Information on the extent to which plants depend on such interactions will help to make more realistic predictions of the potential impacts of disturbances on plant-pollinator networks. Plant functional dependence on pollinators (all interactions pooled) can be estimated by comparing seed set with and without pollinators (i.e. bagging flowers to exclude them). Our main goal in this study was thus to determine whether plant dependence on current insect interactions is related to plant specialization in a pollination network. We studied two networks from different communities, one in a coastal dune and one in a mountain. For ca. 30% of plant species in each community, we obtained the following specialization measures: (i) linkage level (number of interactions), (ii) diversity of interactions, and (iii) closeness centrality (a measure of how much a species is connected to other plants via shared pollinators). Phylogenetically controlled regression analyses revealed that, for the largest and most diverse coastal community, plants highly dependent on pollinators were the most generalists showing the highest number and diversity of interactions as well as occupying central positions in the network. The mountain community, by contrast, did not show such functional relationship, what might be attributable to their lower flower-resource heterogeneity and diversity of interactions. We conclude that plants with a wide array of pollinator interactions tend to be those that are more strongly dependent upon them for seed production and thus might be those more functionally vulnerable to the loss of network interaction, although these outcomes might be context-dependent.     

Limitation of current probe design for oligo-cross-FISH,exemplified by chromosome evolution studies in duckweeds

Chromosoma - Duckweeds represent a small, free-floating aquatic family (Lemnaceae) of the monocot order Alismatales with the fastest growth rate among flowering plants. They comprise five genera...     

新型能源植物浮萍的研究进展

能源需求以及化石能源所产生的环境问题已引起全世界的重视,而浮萍作为一种极具应用潜力生产生物燃料的非粮淀粉原料,目前已受到越来越多的关注。对能源浮萍的生长特性、遗传学和生化方面及其主要应用现状进行综述,并展望浮萍未来的发展前景。     

Neophyten in Mitteleuropa

Neophytes in Central Europe – Success stories of invasive alien plant species Since the 17th century, the introduction of alien plant species has been increasing constantly. They have been introduced intentionally (for example as ornamental garden plants) or accidentally. More than 430 alien species are permanent wild plants in Germany by now, mainly growing in anthropogenic, ruderal habitats without causing any problems. However, some of them build up large, monodominant stands in near‐natural sites. They cause negative impacts on native species diversity, ecosystems or even human health. These species are considered as invasive. They are tough to manage because of their high regenerative capacity and intensive reproduction. Climate change will probably produce more favourable conditions for many of them. Thus preventive action against their further dispersal and against new invasions is of particular importance.     

Stadtamseln sind anders

City blackbirds are different Abiotic factors such as traffic noise and especially artificial light do not just influence species in cities but also change them. The example of the European blackbird (Turdus merula) illustrates how adaptions to city environments can initiate micro‐evolutionary changes. Artificial light clearly alters daily activity patterns and leads to changes in reproductive behaviour: blackbirds sing earlier in the morning, are awake for longer and start reproduction earlier in the year. Traffic noise also changes their song. In order to compensate for interfering traffic noise, city blackbirds sing louder and at higher frequencies. In addition, blackbirds in cities are less curious but also show less fear towards humans than their forest counterparts. Cities have the potential to become a home for some species, but they also change them. One of the big questions of the future will be if, in the globally expanding city environments, this process will lead to the evolution of adapated city species.     

Die Eh da‐Initiative

The “Eh da”‐Initiative: more space for Biological Diversity in Cultural Landscapes The “Eh da”‐initiative is based on the principle that definite land in cultural landscapes is “available anyway” (what ?eh da“ means in German) and has the potential for ecological upgrading without relevant limitations of land use. “Eh da” could be the acronym “Ecological habitat development areas.” This land is located in open landscapes: along waysides, on uncropped plots in farmland, it could be communal lawn and other land categories. The initiative uses geodata in order to detect and quantify “Eh da”‐sites. According to an analysis based on geodata in selected landscapes “Eh da”‐land constitutes 2–6 per cent of the total area of Germany. “Eh da“‐sites are mostly narrow, longitudinal and spread like a net all over the landscape. Mainly insects and other invertebrate animals can be supported by upgrading of “Eh da”‐land. Since these sites often form corridors, they may be part of communal biodiversity protection initiatives under the perspective of ecological networks, or they may be used for distinct projects. Communication is a key element of any local initiative in which not only the ecological upgrading options, but also potential trade‐offs (like increase of agricultural pests and weeds, neophyta and pyrrolizidine containing or allergenic plants) should be discussed.