Hans-Ulrich Jürgens

Feeding behavior of aphids on narrow-leafed lupin (Lupinus angustifolius) genotypes varying in the content of quinolizidine alkaloids

Since the beginning of breeding narrow‐leafed lupins [Lupinus angustifolius L. (Fabaceae)] with a low alkaloid content, susceptibility to several aphid species has increased. Therefore, the probing and feeding behavior of Aphis fabae Scopoli, Aphis craccivora Koch, Acyrthosiphon pisum (Harris), Myzus persicae (Sulzer), and the well‐adapted Macrosiphum albifrons Essig (all Hemiptera: Aphididae) was studied over 12 h on narrow‐leafed lupin genotypes containing varying amounts and compositions of alkaloids. We used the electrical penetration graph (EPG) technique to obtain information on the influence of alkaloid content and composition on the susceptibility to various aphid species. Results indicated that the total time of probing of A. fabae, A. craccivora, A. pisum, and M. persicae increased with a reduced alkaloid content, whereas the alkaloid content had no influence on M. albifrons. Almost all of the individuals (>93%) conducted sieve element phases on the highly susceptible genotype Bo083521AR (low alkaloid content). A reduced occurrence of phloem phases was observed during the 12‐h recording on the alkaloid‐rich cultivar Azuro, especially for A. pisum (37.5%) and A. fabae (55.0%). Furthermore, aphids feeding on genotypes with low alkaloid content had in most cases significantly longer sieve element phases than when feeding on resistant genotypes (Kalya: low alkaloid content, yet resistant; Azuro: high alkaloid content, resistant), whereas M. albifrons showed the longest phloem phase on the alkaloid‐rich cultivar Azuro. As most significant differences were found in phloem‐related parameters, it is likely that the most important plant factors influencing aphid probing and feeding behavior are localized in the sieve elements. The aphids’ feeding behavior on the cultivar Kalya, with a low alkaloid content but reduced susceptibility, indicates that not only the total alkaloid content influences the feeding behavior but additional plant factors have an impact.

Effect of the Soil pH on the Alkaloid Content of Lupinus angustifolius

Field studies were conducted in growing seasons 2004, 2005, and 2010 to investigate the effect of different soil pH values on the alkaloid content in seeds of Lupinus angustifolius. Two-year experiments with eleven cultivars were carried out in acid soils with an average of (Mecklenburg-Western Pomerania) and on calcareous soils with an average pH of 7.1 (Bavaria), respectively. In addition, in 2010, eight cultivars were grown in field experiments in soils with pH values varying between and . In all experiments conducted on soils with a higher pH ( and ), a significantly lower alkaloid content was detected in all Lupinus angustifolius cultivars than on soils with a lower pH ( and ). Results clearly show that the alkaloid content is significantly influenced by the soil pH but genotypic differences regarding the reaction to different pH values in the soil were observed.

Composition, environmental stability and potential of genetic improvement of fatty acids of Lupinus angustifolius

In the last decades procedures for obtaining protein isolates and concentrates derived from narrow-leafed lupins ( L. angustifolius ) for human nutrition have been developed. Since this processes starts with defatting of seeds, lupin oil is obtained in large quantities. Therefore, 50 genotypes of L. angustifolius were analysed regarding the fatty acid (FA) composition of seed oil and the environmental stability of fatty acid contents in order to get information on the application of lupin oil in the food industry. The results revealed an n-3/n-6 poly unsaturated fatty acid ratio of 0.13. Furthermore, the seed oil of L. angustifolius contains rather high amounts of saturated FAs (22%). Significant genotypic differences and a high heritability (h2>85%) for the content of all fatty acids are suggesting that the potential for genetic improvement of fatty acid composition by breeding is given. However, coefficients of variation below 10% for all considered traits point out that a rapid improvement in seed oil quality will be hindered by the narrow genetic base of the breeding material tested.

Phenotyping of Brassica napus genotypes for resistance to drought

The main role of MADS-box transcription factors in plant developmental processes has been well described in the model plant Arabidopsis thaliana. However, little is known about their function in crops of important agricultural and commercial value. Our study aims to investigate their role in two agronomical relevant Rosaceae crops: apple (Malus x domestica Borkh.) and strawberry (Fragaria vesca). Expression studies using qPCR and RNA seq have identified two apple Dormancy Associated MADS-box (DAM) genes. They group with the StMADS11 clade, and were named MdDAM1 and MdDAM2, the last one discovered ex novo. Real time expression studies in dormant buds collected during the chilling period and chromatin immunoprecipitation (ChIP) analyses confirmed that the genes are downregulated by exposure to cold and MdDAM1 is epigenetically repressed, as it has been demonstrated for Arabidopsis FLC and peach DAM genes. In parallel we worked on strawberry MADS-box genes of known function involved in flower development. We chose three MADS-box genes that are homologs of Arabidopsis PISTILLATA and AGAMOUS to perform gene expression and functional analysis using a RNA interference approach to obtain post-transcriptional gene silencing. The positive transgenic lines of each transformation were evaluated at the molecular and phenotypic level. Single gene mutants does not show altered flower phenotype, suggesting a different mechanism of flower development in strawberry, probably due to the peculiar flower structure.The quarantine pest pine wood nematode (PWN) Bursaphelenchus xylophilus, native in North America, can be found in wood and root parts of infected conifer trees with focus on Pinus species. At the beginning of the 20 century this species was introduced into Japan supposedly with timber imports where it induced pine wilt expression on susceptible native pine species. Further outbreaks outside Europe are reported from China, Korea, Taiwan and Mexico. In 1999 PWN was found in Portugal, which today is declared as complete infested, since followed by first single tree outbreaks in Spain. The European Union (EU) member states have to undertake measures to prevent further spread of this nematode according to the emergency measures of the EU Commission.The box tree pyralid Cydalima perspectalis (Walker 1859) is an invasive alien moth from East Asia which occurs in Central Europe since 2007. It is an insect pest on plants of the genus Buxus, causing serious damage. Because of the rapid spread in Germany and nearby countries like Switzerland, one part of this study was testing different ways of eco-friendly regulation with commercially available beneficials and biological control agents.1 Julius Kühn-Institute, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany. 2 Geisenheim Research Center, Section Phytomedicine, Geisenheim, Germany. 3 Área de Genética, Facultad de Ciencias, Universidad de Málaga, Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Málaga (Spain). 4 Suez Canal University, Faculty of Agriculture, Ismailia, Egypt. Email of corresponding author: namis.eltlbany@jki.bund.deExcessive use of mineral nitrogen (N) fertilizer is a common practice in rice-wheat rotations in southeastern China. At the same time N use efficiencies (NUEs) in these rice-based cropping system are very low (Peng et al., 2006). The consequences are high N losses from arable land to water bodies (surfaceand groundwater) and to the atmosphere (Richter and Roelcke, 2000). To investigate the scope and scale of reductions in mineral N fertilizer inputs, demonstration field experiments on farmers’ field sites were conducted for three consecutive winter wheat-summer rice double crop rotations in two counties of Jiangsu Province from 2008 to 2011. Results from the first two years are presented here. NUEsPolycyclic aromatic hydrocarbons (PAHs) are important environmental pollutants which often persist in soil. The biochemistry of microbe-driven degradation of PAHs is well-studied though less is known about abiotic soil environmental factors influencing the microbe-phenanthrene interaction. Since minerals and charcoal are major soil components we matured different microbial communities in artificial soils based only on variation in the mineral content (montmorillonite, illite, ferrihydrite) and presence of charcoal for 2 years after addition of Luvisol microorganisms and sterile manure. Established microbial communities in soils were exposed to PAHs’ model compound phenanthrene (2 mg/g) to study microbial functionality depending on soil composition. Furthermore, litter which was previously shown to enhance microbial activity was added to the soils (1 wt%). Both treatments with corresponding controls were further incubated for 63 days with sampling on day 0, 7, 21 and 63. A natural Luvisol soil was treated similarly for control. Fingerprints by denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA or ITS gene fragments, respectively, amplified from extracted total community DNA were generated. The presence of phenanthrene-degradative genes was screened by PCR-Southern Blot detection and soil treatments were subjected to a chemical phenanthrene analysis. DGGE fingerprints revealed that the addition of phenanthrene and litter caused a shift in microbial community composition. Differences in bacterial response to phenanthrene were seen depending on litter addition and soil composition. The incubation time was determined as additional influencing factor. Furthermore, a dominance of a specific genotype for phenanthrene degradation is assumed based on PCR-Southern Blot analysis.1 Julius Kühn-Institute Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11-12, D-38104 Braunschweig 2 Institute of Crop Science and Resource Conservation, Soil Science and Ecology, University of Bonn, Nussallee 13, D-53115 Bonn 3 Institute of Bioand Geosciences 3, Agrosphere, Forschungszentrum Jülich GmbH, D-52425 Jülich Email of corresponding author: sven.jechalke@jki.bund.de