Project description:Nitrogen (N) fertilization is an important abiotic factor for the growth of potato (S. tuberosum) because of its potential effects on yield. Because excess N in the soil runs off into water systems and negatively impacts the environment, studies on N use by the plant are key to decrease N-fertilizer use. Three commercial potato cultivars (Shepody, Russet-Burbank and Atlantic) were grown under two different rates of applied N-fertilizer (0 kg N ha-1 and 180 kg N ha-1) to obtain more information on the underlying gene regulation mechanisms associated with N. Plants with no added N had significantly lower concentrations of petiole nitrates, chlorophyll level indices, biomass and yield per hectare. Total mRNA samples were taken at two different time-points during the growth season and used for sequencing. The results for each cultivar and time-point were analysed separately to find differentially expressed genes. In total, thirty genes were found to be over-expressed and nine genes were found to be under-expressed in plants from all potato cultivars when they were grown with added N-fertilizer. The 1000 bp upstream flanking regions of the differentially expressed genes were analysed to find overrepresented motifs using three motif discovery algorithms (Seeder, Weeder and MEME). Nine different motifs were found, indicating potential gene regulatory mechanisms for potato under N-deficiency.
Project description:Phloem localization of plant viruses is advantageous for acquisition by sap-sucking vectors but hampers host-virus protein interaction studies. In this study, Potato leafroll virus (PLRV)-host protein complexes were isolated from systemically infected potato, a natural host of the virus. Comparing two different co-immunoprecipitation support matrices coupled to mass spectrometry, we identified 44 potato proteins and one viral protein (P1) specifically associated with virus isolated from infected phloem. An additional 142 proteins interact in complex with virus at varying degrees of confidence. Greater than 80% of these proteins were previously found to form high confidence interactions with PLRV isolated from the model host Nicotiana benthamiana. Bioinformatics revealed that these proteins are enriched for functions related to plasmodesmata, organelle membrane transport, translation and mRNA processing. Our results show that model system proteomics experiments are extremely valuable for understanding protein interactions regulating infection in recalcitrant pathogens such as phloem-limited viruses.
