Entwicklung einer Unterrichtseinheit im Fach Biologie für die gymnasiale Oberstufe (Sekundarstufe II) basierend auf Untersuchungen zur Krankheitsresistenz von Gerste gegen Pilze der Gattung Magnaporthe

  • Development of a teaching sequence in biology for secondary school (Sekundarstufe II) based on investigations of disease resistance in barley to fungi of the genus Magnaporthe

Ulferts, Sylvia; Schaffrath, Ulrich (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2013)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2013

Abstract

In this study current scientific research methodology was linked to education of biology in secondary school by developing teaching aids for students and a teaching sequence based on the results of investigations of disease resistance in barley to fungi of the genus Magnaporthe. A possible impact of phytohormones and hordatines on host- and nonhost- interactions of barley with fungi of the genus Magnaporthe was examined. Generally the exogenous application of phytohormones had a stronger impact on host- than on nonhost interactions. Exogenous application of abscisic acid (ABA) increased susceptibility of barley to M. oryzae (host-interaction) in nearly all barley cultivars examined. This increased susceptibility after ABA-treatment in host-interaction correlates with a reduced accumulation of autofluorescent material in cell wall appositions (papillae) at penetration sides. Additionally, increased susceptibility of barley to M. oryzae was observed in pharmacological studies by application of 2-aminoindan-phosphonic acid (AiP); AiP inhibits L-phenylalanine ammonia-lyase (PAL) enzyme activity, the core enzyme of phenylpropanoid metabolism. After application of AiP the penetration-defense of barley against M. oryzae was reduced as observed by microscopic investigations, which indicates that compounds deriving from phenylpropanoid metabolism, potentially hordatines, are necessary for defense-reactions in barley. An analysis of transcript- accumulation of different genes involved in hordatine- biosynthesis was performed by RT-qPCR during infection of barley with M. oryzae. A histological approach (staining of guanidine compounds) indicates that guanidine containing substances such as hordatines and their precursors contribute to the formation of papillae. Furthermore a barley mutant altered in its wax composition on leaf surface (emr1) was investigated for alterations of pre- penetration infection structures of different plant-pathogenic fungi. To train students knowledge and understanding of current scientific research methodology in biology the barley-powdery mildew (Blumeria graminis f.sp. hordei, Bgh) system was selected as an example for a plant-pathogen interaction, which was tested for use in school. Based on the results of the interactions of barley with Bgh and Magnapothe, respectively, exercises were designed for students in secondary school. All exercises were developed as a modular system, which contains a variety of methods to make scientific texts for students accessible, to perform scientific experiments or to practice handling scientific models. Education standards (Kultusministerkonferenz, 2004) were taken into account to ensure high quality for each exercise to enable students to gain experience in the appropriate skills and requirements. Furthermore, one possible combination of exercises to a teaching sequence is given to show possibilities for use in secondary school. Some exercises have already been tested in school and were evaluated by students.

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