Marasmius oreades agglutinin enhances resistance of Arabidopsis against plant-parasitic nematodes and a herbivorous insect

Background Plant-parasitic nematodes and herbivorous insects have a significant negative impact on global crop production. A successful approach to protect crops from these pests is the in planta expression of nematotoxic or entomotoxic proteins such as crystal proteins from Bacillus thuringiensis (Bt) or plant lectins. However, the efficacy of this approach is threatened by emergence of resistance in nematode and insect populations to these proteins. To solve this problem, novel nematotoxic and entomotoxic proteins are needed. During the last two decades, several cytoplasmic lectins from mushrooms with nematicidal and insecticidal activity have been characterized. In this study, we tested the potential of Marasmius oreades agglutinin (MOA) to furnish Arabidopsis plants with resistance towards three economically important crop pests: the two plant-parasitic nematodes Heterodera schachtii and Meloidogyne incognita and the herbivorous diamondback moth Plutella xylostella. Results The expression of MOA does not affect plant growth under axenic conditions which is an essential parameter in the engineering of genetically modified crops. The transgenic Arabidopsis lines showed nearly complete resistance to H. schachtii, in that the number of female and male nematodes per cm root was reduced by 86-91 % and 43-93 % compared to WT, respectively. M. incognita proved to be less susceptible to the MOA protein in that 18-25 % and 26-35 % less galls and nematode egg masses, respectively, were observed in the transgenic lines. Larvae of the herbivorous P. xylostella foraging on MOA-expression lines showed a lower relative mass gain (22-38 %) and survival rate (15-24 %) than those feeding on WT plants. Conclusions The results of our in planta experiments reveal a robust nematicidal and insecticidal activity of the fungal lectin MOA against important agricultural pests which may be exploited for crop protection

From nutrients to competition processes: Habitat specific threats to Arnica montana L. populations in Hesse, Germany.

Populations of Arnica montana, a characteristic species of nutrient poor grasslands in Central Europe, have been deteriorating over the last decades, especially in lowland regions. Population size has been declining and signs of sexual reproduction are scarce. To start a long-term regeneration program, we investigated the major habitat specific drivers for the decline in Hesse, Germany. Firstly, we conducted a field study to analyze habitat characteristics of 32 Hessian lowland sites, comparing those on which this species has become extinct during the last 15 years with sites of small and declining, as well as large, stable populations. We compared habitat traits focusing on soil parameters, nutrients, and vegetation characteristics. Secondly, we set up a greenhouse experiment to study the response of A. montana seedlings to competition and nutrient input to assess the effects of competition pressure and fertilization. The results show lower carbon-to-nitrogen ratios and higher Ellenberg nitrogen indicator values on sites with extinct populations compared to existing populations. Both pH and Ellenberg soil reaction indicator values were higher on sites with extinct populations. In the greenhouse, the combination of nitrogen addition and competition resulted in lower seedling numbers. While rosette size was not dependent on fertilization, growth was strongly enhanced in the plots lacking vegetation. Both studies suggest that soil nutrient enrichment followed by competition pressure diminishes the number of safe sites for A. montana seedling recruitment and establishment and negatively impacts the growth of existing rosettes, thus leading to the continuous decline of populations. There is an urgent need for actions to reduce unintentional nitrogen deposition in the remaining nutrient poor areas as well as to modify land use to withdraw nutrients from enriched soils in order to preserve the remaining A. montana populations and to create bare ground for the safekeeping and enhancement of self-sustainable populations