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Response of potato and tobacco plants to photoperiod changes

ABSTRACT: Plants of Solanum tuberosum ssp andigena, which tuberize only under SD conditions, were grown in growth chambers under non-inductive LD conditions and half of the plants were transferred to inductive SD conditions for 1 or 15 days, whilst the rest of the plants were kept as controls in LD. Transgenic potato plants with reduced phyB levels, which tuberize irrespective of photoperiod, were also grown in LD conditions. All the plants, irrespective of treatment, were harvested 14 hours after the beggining of the photoperiod (i.e. immediately before dusk for plants on LD, and 8 hours after dusk for the plants on SD). A similar experimental protocol was used with plants of N. tabacum cv Hicks that flower at the same time irrespective of photoperiod and the isogenic line N. tabacum cv Hicks carrying the Maryland Mammoth mutant allele, which flower only on SD (i.e. the plants were grown under LD for 55 or 41 days in LD and then transferred for 1 or 15 days to SD conditions, respectively, whilst control plants were grown 56 days in LD). Finally, Nicotiana silvestris plants that flower only on LD were grown in non-inductive SD and then half of the plants were transferred to inductive LD conditions for 1 or 15 days. In all cases we harvested only the leaves, the organ in which daylength perception takes place and photoperiodic responses are initiated. SD conditions in this experiments were 8 hours of light/ 16 hours of darkness, 160 uEinstein, 22 °C. LD conditions were 16 hours of light/ 8 hours of darkness, 80 uEinstein, 22 °C. RNA was extracted with TRIZOL. Keywords: Direct comparison / Balanced Block Design

ORGANISM(S): Nicotiana sylvestris Solanum tuberosum subsp. andigenum Solanum tuberosum Nicotiana tabacum

PROVIDER: GSE8142 | GEO | 2007/09/01

SECONDARY ACCESSION(S): PRJNA101029

REPOSITORIES: GEO

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Project description:In bacteria, the biosynthesis of cysteine is accomplished by two enzymes that are encoged by the cysK and cysM genes. CysM is also able to incorporate thiosulfate to produce S-sulfocysteine. In plant cells, the biosynthesis of cysteine occurs in the cytosol, mitochondria and chloroplasts. Chloroplasts contain two O-acetylserine(thiol)lyase homologs, which are encoded by the OAS-B and CS26 genes. An in vitro enzymatic analysis of the recombinant CS26 protein demonstrated that this isoform possesses S-sulfocysteine synthase activity and lacks O-acetylserine(thiol)lyase activity. In vivo functional analysis of this enzyme in knockout mutants demonstrated that mutation of cs26 suppressed the S-sulfocysteine synthase activity that was detected in wild type; furthermore, the mutants exhibited a growth phenotype, but penetrance depended on the light regime. The cs26 mutant plants also had reductions in chlorophyll content and photosynthetic activity (neither of which were observed in oas-b mutants), as well as elevated glutathione levels. However, cs26 leaves were not able to properly detoxify ROS, which accumulated to high levels under long-day growth conditions. The transcriptional profile of the cs26 mutant revealed that the mutation had a pleiotropic effect on many cellular and metabolic processes. Our finding reveals that S-sulfocysteine and the activity of S-sulfocysteine synthase play an important role in chloroplast function and are essential for light-dependent redox regulation within the chloroplast. Using the Affymetrix ATH1 GeneChips, we performed a comparative transcriptomic analysis on leaves of the cs26 and wild type plants under two different photoperiod conditions. Wild type and cs26 mutant plants were grown on soil under a long-day photoperiod (LD) or under a short-day photoperiod (SD). Total RNA was extracted from the leaves of 3-week-old plants grown under identical LD conditions, and from the leaves of 5-week-old plants grown under identical SD conditions. Three biological replicates were performed for each sample and hybridized to the chips. We made two different comparisons to classify the differently expressed genes in the mutant plant: cs26 leaves under LD versus wild-type leaves under LD and cs26 leaves under SD versus wild-type leaves under SD.

Project description:Cows exposed to short day photoperiod (SD, 8L:16D) during the 60-day non-lactating period prior to parturition produce more milk in their subsequent lactation compared to cows exposed to long day photoperiod (LD,16L:8D). Although this response is well-established in dairy cows, the underlying mechanisms are not understood. We hypothesized that differential gene expression in cows exposed to SD or LD photoperiods during the dry period could be used to identify the functional basis for the subsequent increase in milk production during lactation. Pregnant, multiparous cows were maintained on a SD or LD photoperiod for 60-days prior to parturition. Mammary biopsies were obtained on days -24 and -9 relative to parturition and Affymetrix GeneChip® Bovine Genome Arrays were used to quantify gene expression. Sixty-four genes were differentially expressed (p ≤ 0.05 and fold-change ≥ |1.5|) between SD and LD treatments. Many of these genes were associated with cell growth and proliferation, or immune function. Ingenuity Pathway Analysis predicted upstream regulators to include TNF, TGFβ1, interferon γ and several interleukins. In addition, expression of 125 genes was significantly different between day -24 and day -9; those genes were associated with milk component metabolism and immune function. The interaction of photoperiod and time affected 32 genes associated with insulin-like growth factor (IGF-I) signaling. Genes differentially expressed in response to photoperiod were associated with mammary development and immune function consistent with the enhancement of milk yield in the ensuing lactation. Our results provide insight into the mechanisms by which photoperiod affects the mammary gland and subsequently lactation. Data were analyzed for the effect of photoperiod treatment (LD minus SD), time relative to parturition (day -24 minus day -9) and the interaction of photoperiod treatment and time ((LD minus SD day -9) minus (LD minus SD day -24))

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Response of potato and tobacco plants to photoperiod changes

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