A flowchart as a tool to support student learning in a laboratory exercise

Practical laboratory exercises are an essential part of university education in natural sciences. The multitude of positive aspects of this active and lively teaching approach is, however, accompanied by some challenges, which have to be observed by the teacher(s) of practical exercises. In this project, a strategy was designed, employed and evaluated to support teaching and student learning in laboratory exercises spread over several days by implementing a flowchart as a central component. Initial co-construction of the flowchart with the students gives ownership of the exercise to the students and forms a common basis for communication and interaction as well as a point of reference throughout the exercise. This approach supported student learning as evidenced by increased understanding of the content and the ability to connect individual parts of the exercise. In addition, it allows the teacher to easily track student progress

Silver Nanoparticles Affect Arabidopsis thaliana Leaf Tissue Integrity and Suppress Pseudomonas syringae Infection Symptoms in a Dose-Dependent Manner

Pathogens are a major threat of plant-based production. Expanding restrictions for the use of classical pesticides is increasing the need of alternative applications to control plant diseases. Nanoparticles have recently received increasing research interest as a potential means to protect plants from adverse conditions including pathogen attack. To assess the beneficial potential of silver nanoparticles to protect plants against the bacterial pathogen Pseudomonas syringae, of which numerous economically relevant pathovars are known, we evaluated the effect of silver nanoparticle pre-treatment in the model pathosystem Arabidopsis thaliana-P. syringae. For this purpose, A. thaliana leaves were treated with different silver nanoparticle concentrations prior to P. syringae infection and visible alterations of the leaf tissue in relation to the individual and combined treatments were scored. While treatment with silver nanoparticles in the concentration range between 0.5 and 10 ppm suppressed P. syringae symptom development, concentrations above 5 ppm caused necroses and chloroses in a dose-dependent manner. This indicates that silver nanoparticles affect plant physiological processes related to cell and tissue integrity that are also associated with the development of infection symptoms caused by P. syringae. Therefore, silver nanoparticle treatments in a suitable concentration range support the maintenance of tissue integrity during pathogen infection in combination with their antimicrobial activity, thus preventing loss of biomass. This makes silver nanoparticles a promising tool for integrative crop protection strategies in commercial production

The Arabidopsis PLAT Domain Protein1 is Critically Involved in Abiotic Stress Tolerance

Despite the completion of the Arabidopsis genome sequence, for only a relatively low percentage of the encoded proteins experimental evidence concerning their function is available. Plant proteins that harbour a single PLAT (Polycystin, Lipoxygenase, Alpha-toxin and Triacylglycerol lipase) domain and belong to the PLAT-plant-stress protein family are ubiquitously present in monocot and dicots. However, the function of PLAT-plant-stress proteins is still poorly understood. Therefore, we have assessed the function of the uncharacterised Arabidopsis PLAT-plant-stress family members through a combination of functional genetic and physiological approaches. PLAT1 overexpression conferred increased abiotic stress tolerance, including cold, drought and salt stress, while loss-of-function resulted in opposite effects on abiotic stress tolerance. Strikingly, PLAT1 promoted growth under non-stressed conditions. Abiotic stress treatments induced PLAT1 expression and caused expansion of its expression domain. The ABF/ABRE transcription factors, which are positive mediators of abscisic acid signalling, activate PLAT1 promoter activity in transactivation assays and directly bind to the ABRE elements located in this promoter in electrophoretic mobility shift assays. This suggests that PLAT1 represents a novel downstream target of the abscisic acid signalling pathway. Thus, we showed that PLAT1 critically functions as positive regulator of abiotic stress tolerance, but also is involved in regulating plant growth, and thereby assigned a function to this previously uncharacterised PLAT domain protein. The functional data obtained for PLAT1 support that PLAT-plant-stress proteins in general could be promising targets for improving abiotic stress tolerance without yield penalty