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:The periderm is a protective barrier crucial for land plants survival, but genetic factors involved in its regulation are fairly unknown. In a previous transcriptomic approach in the cork oak periderm (Quercus suber) we identified a RS2-INTERACTING KH PROTEIN (RIK) homolog, of unknown function and with a K homology (KH)-domain RNA-binding protein, as a regulatory candidate gene in the periderm. To gain insight into the function of RIK in periderm, the potato (Solanum tuberosum) tuber periderm was used as a model. The StRIK transcript profile showed ubiquitous accumulation in all vegetative tissues analyzed, including periderm and other suberized tissues such as root and wound-healing tissues. Downregulation of StRIK in potato by RNA interference (StRIK-RNAi) did not show evident effects in tuber periderm anatomy but unexpectedly unlike Wild type, the transgenic plants flowered. Nevertheless, the periderm of StRIK-RNAi lines did show altered expression of genes associated with RNA metabolism, stress and signaling, mirroring the biological processes found enriched within the in silico co-expression network of the Arabidopsis ortholog. Altogether those findings suggest that the potato StRIK might play roles in RNA maturation and stress response throughout diverse plant developmental processes such as flowering and periderm formation.
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:The goal of the current research is to identify factors that involved with heat induced russeting of the potato tuber skin. Potato plants of the variety Desirèe were grown in pots filled with perlite, in a greenhouse under natural winter conditions (Nov 2005- Jan 2006, average temperatures range of 10-18°C). For the exposure of tubers to heat stress (H) hot water (33-35°C) was circulated in tubes lined at the internal side of the pots. The heat was applied one week before tubers harvest. Tubers were harvested at two time points: 8 weeks post sprouting and a week post mechanical vine killing. The skin (S) of young tubers was peeled by hand, as the remaining phelloderm (PH) layers, the periderm of young tubers (P) and the periderm of mature tubers (ST) were peeled using a scalpel blade. Leaves (L) and tuber flesh (TF) samples were collected as well. For each RNA sample 4 biological replicates were prepared; each one represents pooled tissues from 4-6 plants grown at different location in the greenhouse. RNA was extracted using CTAB protocol, and was further purified by RNeasy Mini Kit (Qiagen) using the On-Column DNase Digestion protocol. Keywords: Loop design 28 hybs total