Abschlussarbeiten

Beet necrotic yellow vein virus (BNYVV) is a member of the genus Benyvirus in the family Benyviridae. BNYVV causes Rhizomania disease in sugar beet, which is characterized by the abnormal proliferation of lateral roots leading to a significant decrease in sugar content and massive yield losses. Therefore, all sugar beet cultivars carry the Rz1 resistance gene preventing infection with BNYVV. However, there are several reports describing the occurrence of Rz1 resistance breaking strains. The high selection pressure has led to several mutations in the pathogenicity factor P25 at amino acid positions 67-70 (AS67-70). Furthermore, an additional RNA component from the P-type (RNA5) has been associated with Rz1 resistance breaking. Experimental studies confirming the resistance breaking effect of the mutations and reassortments are missing. Therefore, a reverse genetic system for sugar beet using a cDNA clone of BNYVV A-type and P-type has been developed at the Institute of Sugar Beet Research. This infection system will be used to study Rz1 resistance breaking by BNYVV in sugar beet. The influence of mutations in the pathogenicity factor P25 will be investigated by PCR mutagenesis. Furthermore, reassortment experiments should be conducted to confirm an effect of RNA5 on resistance breaking. The student will learn modern molecular techniques including PCR mutagenesis, cloning and agroinfection of sugar beet.

Aphids can lead to yield losses in sugar beet production, especially through virus transmission. Insecticides can secure yields, but the number of available substances is limited. Therefore, we are investigating alternative methods of pest control. In the BetaCompP project we test companion plants as a cropping system alternative. One mode of action here is the attraction of aphid predators via more diverse agroecosystems. Tasks: Catching of insects in the field, sample preparation and species/taxonomic determination in the lab. Analysis of the results. Contents can be adjusted to interests. Requirements: You should be interested in field work and arthropods. Prior knowledge is helpful but not required. The thesis can be written in German or English. Period: The main field season is April to July, further analysis in the lab can also be done in autumn/winter.