Acid-stress adaptation in Listeria monocytogenes (Lm) serotype 4b and 1/2a occurred when cells were pre-exposed to pH 5.0 tryptic soy broth supplemented with yeast extract (TSB-YE) at 22°C or 37°C but not at 4°C. Prolonged time, varied sublethal acid pH, substitute of acidulants and addition of sodium chloride during 4°C mild acid pre-exposure still did not induce acid-stress adaptation in Lm. This finding was also validated using an acidic cheese, similar to what has seen for Gram-negative bacteria E. coli and Salmonella. Further investigation revealed that major cold shock protein in Lm CspL was not responsible for repressed acid-stress adaptation at 4°C. A bead beating treatment prior to mild acid pre-exposure at 4°C partially induced acid-stress adaptation after pre-exposure in 4°C to mild acid stress. Our data suggests that cold processing or cold storage temperature can lower the possibility of activating acid-stress adaptation in Lm.

Abiotic stress tolerance and biotic stress resistance have long been targets for trait improvement in the field of plant breeding. To date, much of the target crop focus has been centered on commodity crops such as corn, soybean, wheat, and rice. However, little work has been conducted on improvement of these traits in forage grasses. This is due to a number of issues, particularly that most species are obligately outcrossing, the traits are governed by many genes at unknown loci, and are greatly affected by environmental variation. This creates major complications in successfully selecting and breeding populations of forage grasses tolerant to extreme high or low temperatures, as well as disease resistance. Recurrent phenotypic selection was used to select elite individuals of annual ryegrass (Lolium multiflorum Lam.) and orchardgrass (Dactylis glomerata L.) that expressed improved germination at high temperature. Selections were conducted within growth chambers at fixed temperature and light regimes (40/30 DEGREES C, 12/12 hr, light/darkness) to eliminate environmental variation. Following three cycles of selection, we observed gains (P LESSTHAN 0.001) in selection over the base population for both species. Annual ryegrass mean cumulative germination for cycle 3 peaked at 45.8%, and orchardgrass mean cumulative germination for cycle 3 peaked at 82.67%. Further selection of annual ryegrass for freezing tolerance was also conducted. Flats of unselected germplasm were grown to the three-leaf stage, then frozen for nine hours. Significant differences (P LESSTHAN 0.05) in freezing tolerance were observed between selected germplasm in both cycle 1 (0.076%) and cycle 2 (0.125%) over the unselected cycle 0 (0.025%). Finally, initial stages of resistance breeding work were conducted involving gray leaf spot (causal agent Pyricularia grisea Cke. [Sacc.]) on annual ryegrass. Isolates of the pathogen were obtained and stored for future use. It was determined that the actual pathogen species responsible was Pyricularia oryzae Cavara. Future work for annual ryegrass and orchardgrass germplasm that germinates at high temperatures will involve variety testing and cultivar release. Freezing tolerance and disease resistance work will require larger-scale screening methodology that was able to be conducted in this work to acquire sufficient population sizes for breeding.

Perennial growers overwintering plant stock require information to assist in deciding which containerized plants are most likely to successfully overwinter. Three studies on container-grown herbaceous perennials were conducted to examine the influence of plant age, soil moisture, and temperature cycling date on cold hardiness. In January, plants were exposed to controlled freezing temperatures of -2, -5, -8, -11, and -14C and then returned to a 3-5C greenhouse. In June, plants were assessed using a visual rating scale of 1-5 (1 = dead, 3-5 = increasing salable quality, varying by cultivar) and dry weights of new growth were determined. Controlled freezing in November and March were also included in the third study. In the first study, two ages of plants were exposed to controlled freezing temperatures in January. For Geranium x cantabrigiense 'Karmina', age had no effect on either rating or dry weight in one study year. In two Sedum 'Matrona' study years, age had no effect on dry weight but ratings were higher for older plants than younger plants in the first year and higher for younger plants than older plants in the second year. In two Leucanthemum x superbum 'Becky' study years, age had an effect on both rating and dry weight which were both generally higher for younger plants than older plants. In the second study, plants were maintained in pots at two different soil moisture levels prior to exposure to controlled freezing temperatures in January. Coreopsis 'Tequila Sunrise' and Carex morrowii 'Ice Dance' showed no effect on either rating or dry weight from soil moisture level. Soil moisture level had no effect on dry weight but ratings were higher for Geranium x cantabrigiense 'Cambridge' “wet” plants and for Heuchera 'Plum Pudding' “dry” plants. Carex laxiculmus 'Hobb' (Bunny Blue™) soil moisture level had an effect where dry weight was higher for “dry” plants. Means at were of salable quality for Geranium and Heuchera at all temperatures and Carex laxiculmus at temperatures above -11C. The effects of soil moisture level on Carex oshimensis were inconclusive. In the third study, during November, January, and March, plants were subjected to temperature cycling treatments prior to exposure to controlled freezing temperatures. Geranium x cantabrigiense 'Cambridge' were more tolerant of both temperature cycling and freezing temperatures in January and an increased number of cycles in November had an advantageous effect. Sedum 'Matrona' were more tolerant of temperature cycling and freezing temperatures in January and an increased number of cycles in March had an advantageous effect. Leucanthemum x superbum 'Becky' were more tolerant of temperature cycling in January in the second year of the study and an increased number of cycles in November had an advantageous effect in the first year and in all months in the second year. Overwintering younger container-grown plants is likely to result in more growth and higher quality following exposure to freezing temperatures. Effects of soil moisture level on overwintering container-grown plant growth and quality are cultivar-specific and a general effect could not be established in these studies. Overwintering container-grown plants are likely to be hardier in January and slight temperature cycles prior to exposure to freezing temperatures generally increase hardiness.

<p></p><p></p><p>Abiotic stresses, such as cold, are serious agricultural problems resulting in substantial crop and revenue losses. Soybean (<i>Glycine max</i>) is an important worldwide crop for food, feed, fuel, and other products. Soybean has long been considered to be cold-intolerant and incapable of cold acclimation. In contrast to these reports, this study demonstrates that cold acclimation improved freezing tolerance in the domestic soybean cultivar ‘Williams 82’ with 50% enhancement of freezing tolerance after 5.2 +\- 0.6 days of cold exposure. Decreases in light dependent photosynthetic function and efficiency accompanied cold treatment. These decreases were due to an increase in photon dissipation likely driven by a decrease in plastoquinone (PQ) pool size limiting electron flow from photosystem II (PSII) to photosystem I (PSI). Cold-induced damage to operational photosynthesis began at 25 minutes of cold exposure and maximal photosynthesis was disrupted after 6 to 7 hours of cold exposure. Cold exposure caused severe photodamage leading to the loss of PSII reaction centers and photosynthetic efficiency.</p> <p>Comparisons of eight cultivars of <i>G. max</i> demonstrated a weak correlation between cold acclimation and northern cultivars versus southern cultivars. In the non-domesticated soybean species <i>Glycine soja</i>, the germination rate after cold imbibition was positively correlated with seedling cold acclimation potential. However, the overall cold acclimation potential in <i>G. soja</i> was equal to that of domestic soybean <i>G. max</i> reducing the enthusiasm for the “wild” soybean as an additional source of genetic diversity for cold tolerance. </p> <p> </p> <p>Despite being relatively cold intolerant, the soybean genome possesses homologs of the major cold responsive CBF/DREB1 transcription factors. These genes are cold-induced in soybean in a similar pattern to that of the cold tolerant model plant species Arabidopsis thaliana. In Arabidopsis, EIN3, a major component of the ethylene signaling pathway, is a negative transcriptional regulator of CBF/DREB1. In contrast to <i>AtEIN3</i> transcript levels which do not change during cold treatment in Arabidopsis, we observed a cold-dependent 3.6 fold increase in <i>GmEIN3 </i>transcript levels in soybean. We hypothesized that this increase could prevent effective CBF/DREB1 cold regulation in soybean. Analysis of our newly developed cold responsive reporter (<i>AtRD29Aprom::GFP/GUS</i>) soybean transgenic lines demonstrated that inhibition of the ethylene pathway via foliar sprays (AVG, 1-MCP, and silver nitrate) resulted in significant cold-induced GUS activity. Transcripts of <i>GmEIN3A;1</i> increased in response to ethylene pathway stimulation (ACC and ethephon) and decreased in response to ethylene pathway inhibition in the cold. Additionally, in the cold, inhibition of the ethylene pathway resulted in a significant increase in transcripts of <i>GmDREB1A;1</i> and <i>GmDREB1A;2</i> and stimulation of the ethylene pathway led to a decrease in <i>GmDREB1A;1</i> and <i>GmDREB1B;1</i> transcripts. To assess the physiological effects of these transcriptional changes; electrolyte leakage, lipid oxidation, free proline content, and photosynthesis were examined. Improvement in electrolyte leakage, a measure of freezing tolerance, was seen only under silver nitrate treatment. Only 1-MCP treatment resulted in significantly decreased lipid oxidation. Transcripts for CBF/DREB1 downstream targets (containing the consensus CRT/DRE motifs) significantly decreased in plants treated with ethylene pathway stimulators in the cold; however, ethylene pathway inhibition generally produced no increase over basal cold levels. </p> <p> </p> <p>To identify if GmEIN3A;1 was capable of binding to <i>GmDREB1</i> promoters, the negative regulator GmEIN3A;1 and the positive regulator GmICE1A were cloned and expressed in Escherichia coli (E. coli). Preliminary binding results indicated that GmEIN3A;1 can bind to a double stranded section of the GmDREB1A;1 promoter containing putative EIN3 and ICE1 binding sites. GmICE1A is capable of binding to the same section of the <i>GmDREB1A;1</i> promoter, though only when single stranded. Additional experiments will be required to demonstrate that GmEIN3A;1 and GmICE1A are capable of binding to the <i>GmDREB1A;1</i> promoter and this work provides the tools to answer these questions. </p> <p> </p> <p>Overall, this work provides evidence that the ethylene pathway transcriptionally inhibits the CBF/DREB1 pathway in soybean through the action of GmEIN3A;1. Yet when <i>GmCBF/DREB1</i> transcripts are upregulated by ethylene pathway inhibition, no consistent change in downstream targets was observed. These data indicate that the limitation in cold tolerance in soybean is due to a yet unidentified target downstream of CBF/DREB1 transcription.</p><p></p><p></p>

The first part of this research focused on wide-cross whole-genome radiation hybrid (WWRH) mapping of the cotton (Gossypium) genome. Radiation hybrid mapping has been used extensively to map the genomes of human and certain animal species, but not plant species. In lieu of in vitro hybrid cell line technologies for plants, we developed a novel approach for radiation hybrid mapping based on wide-cross in vivo hybridization. Flowers from one species of cotton, either G. hirsutum or G. barbadense, were -irradiated and then used to pollinate the other species. The resulting hybrid plants were assessed as a mapping tool. Two WWRH mapping panels were constructed from 5- and 8-krad -irradiation treatments. Both panels demonstrated that the WWRH mapping method can be used to map the cotton genome, and that this method complements traditional linkage mapping approaches. The second part of this research focused on the identification of cold-responsive genes using spotted oligo-gene microarray analysis. Increased cold-tolerance in cotton would promote early and uniform seedling establishment, expand the growing season, decrease susceptibility to fungal infections and certain diseases, and increase fiber yield and quality. BLAST searches of the cotton database using amino acid sequences of 93 drought/cold-related genes from Arabidopsis and several other plant species led to 806 cotton orthologous cDNAs and expressed sequence tags (ESTs). Eight hundred and six cotton 70-mer oligos were designed and included in an oligo-gene microarray containing 1,536 70-mer oligos, each representing a cDNA or EST from cotton, or one of 121 chloroplast genes or 66 mitochondrial genes from Arabidopsis. Thirty-eight cotton cDNAs and ESTs were identified as cold-responsive genes based on experimental treatment and oligo-gene microarray analysis. Expression was up-regulated for 36 genes and down-regulated for two genes by cold treatment. Results from microarray analysis were tested and confirmed by northern blot analysis for 16 genes. Our data suggest that Arabidopsis orthologous genes can be used to identify homologous cotton genes. The oligo-gene microarray is a valid approach to study transcriptional changes in cotton.

No description available.

In this study, effect of cold stress and recovery on the superoxide dismutase (SOD) activities and the expression levels of Cu/ZnSOD gene were investigated in two barley cultivars (Tarm-92-winter type, Zafer-160-spring type). Eight days old barley seedlings were subjected to two different cold stresses / chilling stress at 4&deg / C for 1, 3, 7 days and freezing stress at -3&deg / C and -7&deg / C. Analyses were performed both on leaf and root tissues. The SOD activities and isozyme patterns were determined by Native PAGE activity staining technique. Relative RT-PCR was used for the transcript levels of Cu/ZnSOD gene. The SOD activities and expression levels of control and cold stressed plants were compared by densitometric analysis. Under chilling stress, the activities of Cu/ZnSODx and Cu/ZnSOD2 did not have any significant change in leaf and root tissues of both cultivars. However, the expression levels of Cu/ZnSOD gene were more variable than activity results. After -3&deg / C freezing stress, the activities of SOD enzyme in leaf tissues of Tarm-92 increased significantly, however, these activities significantly decreased in leaves of Zafer-160. These results suggested that both cultivars were not affected by chilling stress in terms of SOD enzyme activities and expression levels. Furthermore, under freezing stress conditions, the increment of SOD activities and expression levels in Zafer-160 was higher than Tarm-92. In conclusion, the changes in SOD isozyme activities and expression levels may not be enough for understanding of the cold stress mechanism. Therefore, further studies have to be carried on other antioxidant enzyme systems.

In this study, effect of cold stress on physiology and biochemistry of two Turkish barley cultivars, winter type Tarm-92 and spring type Zafer-160, was studied. For chilling stress treatment, cultivars were exposed to +4 &ordm / C for 1, 3 and 7 days, and for freezing stress application acclimated cultivars (+4 &ordm / C for 3 days) were treated with -3 &ordm / C and -7 &ordm / C. After freezing stress treatment, a recovery period was applied for 4 days at 4 &ordm / C. Following analyses were performed on leaf and root tissues: growth parameters (length, wet-dry weights), malondialdehyde (MDA) content, proline content, hydrogen peroxide content (H2O2) electrolyte leakage, PS II fluorescence (Fv/Fm), antioxidant enzyme activities such as catalase (CAT: EC 1.11.1.6), ascorbate peroxidase (APX: EC 1.11.1.11) and glutathione reductase (GR: EC 1.6.4.2). It was observed that effect of cold was more at freezing temperatures than chilling temperature. Cold dependent damage was more obvious as the duration of chilling temperature increased. Growth retardation, membrane damage, leaf catalase deactivation were more apparent and leaf glutathione reductase activity increase was less in spring type cultivar Zafer than in winter type Tarm. These results indicated that winter type barley cultivar is more cold tolerant than spring type barley.

Rhodobacter capsulatus DSM1710 is a purple non-sulfur bacterium capable of hydrogen production via photofermentation. Biohydrogen is a clean and renewable way of hydrogen production, which can be achieved by PNS bacteria in outdoor large scale photobioreactors using sun light. In outdoor conditions bacteria can be exposed to heat and cold stress. In this study in order to understand the effects of heat and cold stress on photofermentative hydrogen production and gene expression profile of R.capsulatus on acetate as the carbon source, microarray analysis was carried out. Since there is no commercially available microarray chip for R.capsulatus, an Affymetrix GeneChip&reg / was designed and it was manufactured by Affymetrix.The experiments were conducted at 30

The first part of this research focused on wide-cross whole-genome radiation hybrid (WWRH) mapping of the cotton (Gossypium) genome. Radiation hybrid mapping has been used extensively to map the genomes of human and certain animal species, but not plant species. In lieu of in vitro hybrid cell line technologies for plants, we developed a novel approach for radiation hybrid mapping based on wide-cross in vivo hybridization. Flowers from one species of cotton, either G. hirsutum or G. barbadense, were &#61543;-irradiated and then used to pollinate the other species. The resulting hybrid plants were assessed as a mapping tool. Two WWRH mapping panels were constructed from 5- and 8-krad &#61543;-irradiation treatments. Both panels demonstrated that the WWRH mapping method can be used to map the cotton genome, and that this method complements traditional linkage mapping approaches. The second part of this research focused on the identification of cold-responsive genes using spotted oligo-gene microarray analysis. Increased cold-tolerance in cotton would promote early and uniform seedling establishment, expand the growing season, decrease susceptibility to fungal infections and certain diseases, and increase fiber yield and quality. BLAST searches of the cotton database using amino acid sequences of 93 drought/cold-related genes from Arabidopsis and several other plant species led to 806 cotton orthologous cDNAs and expressed sequence tags (ESTs). Eight hundred and six cotton 70-mer oligos were designed and included in an oligo-gene microarray containing 1,536 70-mer oligos, each representing a cDNA or EST from cotton, or one of 121 chloroplast genes or 66 mitochondrial genes from Arabidopsis. Thirty-eight cotton cDNAs and ESTs were identified as cold-responsive genes based on experimental treatment and oligo-gene microarray analysis. Expression was up-regulated for 36 genes and down-regulated for two genes by cold treatment. Results from microarray analysis were tested and confirmed by northern blot analysis for 16 genes. Our data suggest that Arabidopsis orthologous genes can be used to identify homologous cotton genes. The oligo-gene microarray is a valid approach to study transcriptional changes in cotton.