Effects Of Low Temperature Stress Research Articles

Effects of low temperature stress on chloroplast development in a range of Zea mays cultivars

One photosynthetic characteristic, chloroplast development, was used to evaluate tolerance to chilling in a range of Zea mays L. cultivars. Seedlings of six different cultivars of Zea mays were grown in controlled environment chambers at daytime temperatures of 14 °C, 17 °C and 25 °C and their thylakoid polypeptide profiles examined. With reduced growth temperature decreases in many polypeptides were observed, particularly those with apparent molecular masses ranging from 30–42 kDa, 43–67 kDa and 68–71 kDa. However, a number of other polypeptides with lower apparent molecular masses ranging from 14–20 kDa accumulated in some cultivars at the lower growth temperatures, especially at 14 °C. The comparatively uniform reduction in specific thylakoid polypeptides at lower growth temperatures in the six cultivars examined suggest that thylakoid polypeptide profiles may be used as a criterion for screening low temperature tolerance in maize lines.

Overproduction of Photosynthetic Electrons is Associated with Chilling Injury in Green Leaves

Employing the non-invasive techniques of infra-red gas analysis and pulse amplitude modulated chlorophyll fluorometry, we determined the partitioning of photosynthetic electrons between photosynthetic carbon reduction and other reductive processes resulting in the formation of active oxygen species (AOS) in intact green leaves. This we studied in plant species that are adapted to two different agro-climatic conditions, namely the warm plains (76°36'E, 9°32'N) and the cool mountains (1 600 m a.s.l.) in the south Indian state of Kerala. Ground frost and low temperature were more harmful to those species adapted to the warm plains than the ones adapted to the cool mountains. Exposure to low temperature decreased leaf photosynthetic carbon assimilation rates and quantum yield of photochemical activity in species naturally adapted to the warm plains. High irradiances further aggravated the harmful effects of low temperature stress possibly by overproducing AOS. This resulted in severe peroxidative damage as inferred by the accumulation of malondialdehyde (MDA) in the leaves.

Thermoluminescence Investigation of Low Temperature Stress in Maize

The thermoluminescence (TL) emission of photosynthesising materials originates from the recombination of charge pairs created by a previous excitation. Using a recently described TL set-up the effect of chilling stress on TL bands occurring at positive temperatures (AG, B, and HTL) was investigated in intact leaves. The far-red irradiation of leaves at low, but non-freezing temperatures induced a TL band peaking at around 40–45 °C (AG band), together with a B band peaking between 20 and 35 °C. Low temperature stress first caused a downshift and a temporary increase in the AG band after 4 h at 0 °C in the light, then a decrease in the AG and B TL bands after 1 d at 0 °C in the light. This decrease was less pronounced in cold-tolerant genotypes and in those grown at acclimating temperatures. Furthermore, an additional band appeared above 80 °C after severe cold stress. This band indicates the presence of lipid peroxides. Thus TL is a useful technique for studying the effects of low temperature stress.

Changes in glycolytic activity of Lactococcus lactis induced by low temperature.

The effects of low-temperature stress on the glycolytic activity of the lactic acid bacterium Lactococcus lactis were studied. The maximal glycolytic activity measured at 30 degrees C increased approximately 2.5-fold following a shift from 30 to 10 degrees C for 4 h in a process that required protein synthesis. Analysis of cold adaptation of strains with genes involved in sugar metabolism disrupted showed that both the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) subunit HPr and catabolite control protein A (CcpA) are involved in the increased acidification at low temperatures. In contrast, a strain with the PTS subunit enzyme I disrupted showed increased acidification similar to that in the wild-type strain. This indicates that the PTS is not involved in this response whereas the regulatory function of 46-seryl phosphorylated HPr [HPr(Ser-P)] probably is involved. Protein analysis showed that the production of both HPr and CcpA was induced severalfold (up to two- to threefold) upon exposure to low temperatures. The las operon, which is subject to catabolite activation by the CcpA-HPr(Ser-P) complex, was not induced upon cold shock, and no increased lactate dehydrogenase (LDH) activity was observed. Similarly, the rate-limiting enzyme of the glycolytic pathway under starvation conditions, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was not induced upon cold shock. This indicates that a factor other than LDH or GAPDH is rate determining for the increased glycolytic activity upon exposure to low temperatures. Based on their cold induction and involvement in cold adaptation of glycolysis, it is proposed that the CcpA-HPr(Ser-P) control circuit regulates this factor(s) and hence couples catabolite repression and cold shock response in a functional and mechanistic way.

Effect of Cycling Temperatures on the Production of Deoxynivalenol and Zearalenone by Fusarium graminearum NRRL 5883

The effects of three regimens of cycling incubation temperatures and incubation at constant 25°C on the growth of Fusarium graminearum NRRL 5883 and production of deoxynivalenol (DON) and zearalenone (ZEN) on rice were compared. The effects of low-temperature stress were also studied by incubating rice cultures at a constant 15°C for 4 weeks following incubation at constant 25°C for 2 weeks. Both incubation temperature and time significantly (P ≤ 0.05) affected growth of F. graminearum NRRL 5883 and production of DON and ZEN. The highest amount of free ergosterol (640 μg/g culture material) that was used as a measure of fungal growth was found in cultures incubated at temperatures cycling between 15 and 30°C during a 6-week period. The highest amounts of DON (1,679 μg/g culture material) and ZEN (603 μg/g culture material) were produced in cultures incubated at a constant 25°C for 2 weeks prior to incubation at a constant 15°C for an additional 4 weeks. Under cycling incubation temperatures, maximum amounts of DON (850 μg/g culture material) and ZEN (98 μg/g culture material) were produced in cultures incubated at temperatures cycling between 15 and 30°C for 6 weeks. Overall, there was no correlation between mold growth and production of either DON or ZEN. However, DON production and ZEN production were correlated.

Low‐Temperature Tolerance in Cereals: Model and Genetic Interpretation

Exposure of plants to low temperature (LT) produces a myriad of measurable changes in morphological, biochemical, and physiological characters that are often highly correlated with plant cold tolerance. These complicated responses have made it difficult to separate cause-and-effect adjustments to LT, emphasizing the need for a descriptive framework for the integration of current knowledge so that research efforts can be better focused. The objective of this study was to construct a functional model that complies with the known LT responses of cereals so production risks, cause-and-effect processes, and genetic theories can be systematically investigated. In the model, a series of equations describe acclimation, dehardening, and damage due to LT stress. A modular design permits modification and allows the model to be interfaced with other simulation models that input or compute daily measurements of soil temperature and phonological development. LT tolerance is estimated on a daily basis relative to phenological stage and the input of a genetic coefficient is required. Operation of the model is consistent with recent interpretation of LT-gene regulation and it is especially sensitive to the switching signals that down-regulate LT-gene expression in plants maintained for long periods of time in the optimum temperature range for cold acclimation. Simulation studies have also shown that small differences in cultivar genetic potential translate into large differences in LT tolerance when the cumulative effects of LT stress enter the critical range for overwinter survival. The model has been field validated for cereals overwintered in Saskatchewan, Canada, but it also has potential application in the simulation of LT responses of a wide range of species and climates.

Effects of low-temperature stress on development of winter crown rot in first-year alfalfa

The effects of sub-lethal low temperatures on predisposing first-year alfalfa plants to infection by the low temperature basidiomycete (LTB), and the effects of sub-lethal winter crown rot levels on alfalfa cold hardiness were evaluated in controlled environment and field studies. Alfalfa, subjected to the sublethal stress temperature of –7.5 °C for 1 to 5 wk and inoculated with LTB, exhibited higher mortality, lower shoot dry weights, and higher winter crown rot levels than alfalfa similarly inoculated but non-stressed. Inoculation and incubation of alfalfa with the LTB fungus for 4 wk decreased the freezing resistance of cv. Barrier and cv. Peace alfalfa by 26 and 32%, respectively, compared with the non-inoculated controls. Following inoculation and incubation with LTB, stress temperatures between −6 and −15 °C increased LTB induced mortality in Barrier by 17–54% and in Peace by 10–75%. These results demonstrate that sub-lethal low-temperature stress can act synergistically with winter crown rot pathogen to reduce survival and yield in first-year alfalfa. Key words: Medicago sativa L., alfalfa, low temperature, winter crown rot, Coprinus psychromorbidus

Nitrogen fixation and nitrate metabolism for growth of six diverse soybean [ Glycine max. (L.) Merr.] genotypes under low temperature stress

Soybean [ Glycine max (L.) Merr] is a subtropical legume that is at the northern limit of its range in the cool temperate zone of North America. Low temperature stress inhibits N 2 fixation and NO 3 metabolism in soybean. A controlled environment experiment was conducted to test the effects of low temperature stress (16/9°C day/night versus 26/19°C) on N 2 fixation and NO 3 metabolism of one American, one northern Chinese, one Polish, one Swedish and two Canadian soybean cultivars. The objectives of this work were to measure variability in N 2 fixation, NO 3 use, and plant growth under low and optimal temperature regimes among these diverse genotypes, and to determine the physiological bases for these differences. The results showed that: (1) the relative ranking of cultivars for growth and accumulation is different between nitrogen sources under optimal or suboptimal temperatures; (2) the cultivars which are better able to fix N 2 usually have more nodule mass; (3) the plants which fix more N 2 allocate less photosynthate to the plant root system, and (4) there was no negative relationship between N 2 fixation or NO 3 utilization among the cultivars tested.

Effect of low temperature stress on the expression of sucrose synthetase in spring and winter wheat plants. Development of a monoclonal antibody against wheat germ sucrose synthetase

A monoclonal antibody against wheat germ sucrose synthetase is developed and characterized. Its use in studying the effect of cold acclimation on the expression of sucrose synthetase in winter and spring wheat plants is described. The antibody shows cross-reactivity with sucrose synthetase from maize and pea plants, as well as carrot cells. A gradual accumulation of the enzyme as a function of time spent at 2 degrees C is observed in both wheat varieties. In contrast, an initial sharp rise in the mRNA level is observed, which agrees with the previously reported response of maize plants subjected to anaerobic stress.

Response of Rice Leaves to Low Temperature I. Changes in Basic Biochemical Parameters

It has been reported that, in rice plants, the growth rate and metabolism are markedly inhibited at temperatures above the chilling temperature, in the range between about 15-20°C. Nevertheless, there are few reports on the mechanism of the effects of low-temperature stress on growth and the accompanying metabolic changes. Therefore, we have investigated the effects of low temperature on the rate of growth and increases in levels of chlorophyll and proteins, the most basic biochemical parameters of cellular functions, in the developing green leaves of two rice cultivars with different sensitivities to low temperatures, namely, a low-temperature sensitive variety, Indica type IR8, and a low-temperature tolerant variety, Japonica type Somewake

Effects of low-temperature stress on the metabolism of phosphatidylglycerol molecular species in Dunaliella salina

A detailed analysis was made of individual phosphatidylglycerol (PG) molecular species isolated from microsomes and chloroplasts at various times after labeling Dunaliella salina cells with [ 14C]palmitic, [ 14C]oleic, or [ 14C]lauric acid. The patterns of [ 14C]fatty acid incorporation were in agreement with PG being formed by the “eucaryotic” type pathway in microsomes and the “procaryotic” type pathway in chloroplasts. In Dunaliella, which lacks a quantitatively significant flux of eucaryotic-type lipids from microsomes into chloroplast glycolipids, indications were found for a more subtle movement of microsomally synthesized PG into the chloroplasts. This transfer was more evident in cells stressed by exposure to 12 °C than it was at 30 °C, and may afford a mechanism for recruiting key microsomal PG molecular species toward low-temperature acclimation in chloroplasts.

STUDYING OF FROST RESISTANCE OF CHERRY VARIETIES IN SELECTION OF ALL-RUSSIAN RESEARCH INSTITUTE FOR FRUIT CROP BREEDING

The studies were conducted on the basis of the laboratory physiology resistance of fruit plant at the Russian Research Institute of Fruit Crop Breeding in 2017-2018. The objects of research were cherry varieties by the Institute selection. The year of setting was 2015. The scheme of setting – 5×2 m. Inter-row spacing and zone near a tree trunk – weedfree fallow. The purpose of the research was to study some physiological and biochemical adaptation processes in the autumn-winter period and evaluated the frost resistance of cherry varieties by artificial freezing method. The dynamics of the fractional composition of water in the tissues of annual branches of cherry varieties was studied. At the same time, the maximum proportion of bond water to free water was found in the varieties Bystrinka, Livenskaia, Muza, Novella, Shokoladnitsa. During the autumn period, the increase of bound water and the decrease of free water depended on the accumulation of the amino acid proline in annual cherry branches. The high level of dependence of bound to free water ratio and the proline amount on the minimum air temperature in the autumn period was noticed in the cherry varieties, which were studied. At the beginning of winter, the average dependence between the degree of freezing of varieties and the amount of bound water in the tissues of annual cherry branches was established. The dependence of the accumulation of the amino acid proline on the effects of low-temperature stress in winter was revealed. The resistance to early winter frosts (t = -25°C) was marked in all studied cherry varieties. The maximum frost resistance was marked in Livenskaia, Novella, Orlitsa, Shokoladnitsa varieties at t = -35°C. As a result of artificial freezing, frost-resistant varieties of cherry Livenskaia, Novella and Shokoladnitsa, which showed the highest level of resistance of generative and vegetative buds, bark and wood substance to the damaging factors of winter, were identified.