Project description:St (common potato) is a freezing sensitive species unable to cold acclimate. The close wild relative Sc is freezing tolerant and able to cold acclimate. Here we compare the cold transcriptome of these two species with different levels of freezing tolerance. We also identify the putative CBF regulons by comparing the transcriptomes of wild type plants with that of 35S::AtCBF3 transgenic lines in both species.
Project description:The potato is susceptible to water stress at all stages of development. We examined four clones of tetraploid potato, Cardinal, Desirée, Clone 37 FB and Mije, from the germplasm bank of the National Institute of Agricultural Research (INIA) in Chile. Water stress was applied by suspending irrigation at the beginning of tuberization. Stomatal conductance, tuber and plant fresh and dry weight was used to categorize water stress tolerance. Cardinal had high susceptibility to water stress. Desirée was less suscepetible than Cardinal and had some characteristics of tolerance. Mije had moderate and Clon 37 FB high tolerance. Differential gene expression in leaves from plants with and without water stress were examined using transcriptome sequencing. Water stress susceptible Cardinal had the fewest differentially expressed genes at 101, compared to Desirée at 1867, Clon 37 FB at 1179 and Mije at 1010. Water stress tolerance was associated with up-regulation of expression of transcription factor genes and genes involved in osmolyte and polyamine biosynthesis. Increased expression of genes encoding late embryogenesis abundant (LEA) and dehydrin proteins along with decreased expression of genes involved in nitrate assimilation and amino acid metabolism were found for clones showing water stress tolerance. The results also show that water deficit was associated with reduced biotic stress responses. Additionally, heat shock protein genes were differentially expressed in all clones except for highly susceptible Cardinal. Together the gene expression study demonstrates variation in the molecular pathways and biological processes in response to water stress contributing to tolerance and susceptibility.
Project description:St (common potato) is a freezing sensitive species unable to cold acclimate. The close wild relative Sc is freezing tolerant and able to cold acclimate. Here we compare the cold transcriptome of these two species with different levels of freezing tolerance. We also identify the putative CBF regulons by comparing the transcriptomes of wild type plants with that of 35S::AtCBF3 transgenic lines in both species. Plants were grown in 16:8 photoperiod. Eight hours after dawn, plants were either transfered to cold or kept in the warn. Wild type S. tuberosum and S. commersonii were grown at 2oC for 2h, 24h and 7 days. Wild type plants grown under warm temperatures for 2h was used as control for 2h cold samples; wild type warm grown plants for 24h were used as controls for 24h and 7 days cold samples. Under warm conditions, S. commersonii 35S::AtCBF3 lines were compared to S. commersonii wild type plants (same thing was done for S. tuberosum).
Project description:Although significant work has been undertaken regarding the response of model and crop plants to heat shock during the acclimatory phase, few studies have examined the steady state response to the mild heat stress encountered in temperate agriculture. In the present work we therefore exposed tuberising potato plants to mildly elevated temperatures (30/20C), day/night) for up to five weeks and compared tuber yield, physiological and biochemical responses, and leaf and tuber metabolomes and transcriptomes with plants grown under optimal conditions (22/16C). Growth at elevated temperature reduced tuber yield despite an increase in net foliar photosynthesis. This was associated with major shifts in leaf and tuber metabolite profiles, a significant decrease in leaf glutathione redox state and decreased starch synthesis in tubers. Furthermore, growth at elevated temperature had a profound impact on leaf and tuber transcript expression with large numbers of transcripts displaying a rhythmic oscillation at the higher growth temperature. RT-PCR revealed perturbation in the expression of circadian clock transcripts including StSP6A, previously identified as a tuberisation signal. Our data indicate that potato plants grown at moderately elevated temperatures do not exhibit classic symptoms of abiotic stress but that tuber development responds via a diversity of biochemical and molecular signals. In this submission we are looking at gene expression changes with respect to both temperature and time, every 4h over a 24h period whereby diurnal changes may be apparent.
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.