Long-term effects of temperature shifts on xanthophyll cycle and photoinhibition in spinach (Spinacia oleracea)

1999 ◽  
Vol 26 (2) ◽  
pp. 125 ◽  
Author(s):  
G. H. Krause ◽  
N. Carouge ◽  
H. Garden

The present study tested with spinach (Spinacia oleracea L.), whether leaves are capable of long-term acclimative responses of carotenoids when warm-grown (20°C) plants were subjected to a regime of low temperature (1–6°C) and excess light (250 mol m–2 s–1). About 17 days after the temperature shift, leaves of the third leaf pair were compared with the respective leaves of warm-grown control plants. The cold-treated leaves exhibited reduced susceptibility to photoinhibition (at 4°C) and considerably faster kinetics of ‘recovery’ (at 20°C), as determined by changes in the ratio of dark-adapted variable to maximum chlorophyll fluorescence, FV/FM. The temperature shift induced marked changes in the composition of photosynthetic pigments. In particular, the pool of xanthophyll cycle pigments, viola-, anthera- and zeaxanthin, based on chlorophyll a+b, was enlarged by about 50%. The proportion of xanthophyll cycle pigments referred to the sum of carotenoids increased by about 25% and, in excessive light, a larger fraction of violaxanthin became deepoxidized. Overall, in respect of carotenoid composition and xanthophyll cycle activity, leaves that had been acclimated by temperature shift were very similar to leaves acclimated by growth in the field during autumn and winter. The data show that in spinach leaves, photoprotective mechanisms can be induced by temperature shift without requirement for development and growth at low temperature.

1999 ◽  
Vol 54 (9-10) ◽  
pp. 645-657 ◽  
Author(s):  
Carina Barth ◽  
G. Heinrich Krause

The responses of photosystems (PS) I and II to light stress at 4 °C and 20 °C were studied in leaf discs from three chilling-sensitive plant species, Cucumis sativus, Cucurbita maxima and Nicotiana tabacum, and in the chilling-tolerant Spinacia oleracea. The chilling-sensitive plants were grown at 24 °C under 80 -120 μmol photons m-2 s-1 (Cucumis and Cucurbita) or 30 μmol photons m-2 s-1 (Nicotiana). Spinacia was cultivated outdoors during winter and early spring. The P700 absorbance change around 820 nm served as a relative measure of PSI activity. The potential efficiency of PSII was determined in dark-adapted leaf discs by means of the ratio of variable to maximum chlorophyll (Chl) a fluorescence emission (Fv/Fᴍ). In Cucurbita, Nicotiana and Spinacia, PSI was not or only slightly inhibited by 2 h illumination with 200 μmol m-2 s-1 at 4 °C or with 2000 μmol m-2 s-1 at 20 °C. In leaves of Cucurbita and Nicotiana, exposure to 2000 μmol photons m-2 s-1 at 4 °C resulted in a decline in PSI activity and potential PSII efficiency approximately to the same extent (about 50% within 2 h). In contrast, in Cucumis, both moderate and high light at low temperature caused a PSI inhibition that proceeded considerably faster than the decline in PSII efficiency. Such preferential photoinhibition of PSI was not observed in the other three species tested. In Spinacia, a lower susceptibility of PSI and PSII to photoinhibition at 4 °C was associated with a faster de-epoxidation kinetics of violaxanthin, as compared to the three chilling-sensitive species. In addition, leaves of Spinacia were characterized by a significantly larger pool of xanthophyll-cycle pigments and a higher content of β-carotene based on Chi a+b. When leaves of Cucurbita were preincubated with methylviologen, which catalyzes formation of superoxide anion radicals at the acceptor side of PSI, the decline in potential PSII efficiency under 2000 μmol photons m-2 s-1 at 20 °C and 4 °C was strongly enhanced, whereas the P700 signal was less affected. Our data demonstrate that in the species tested, PSI may be inhibited in vivo besides PSII under light stress, but preferential photoinhibition of PSI is not a general phenomenon in chilling-sensitive plants. At low temperatures, a reduced function of the xanthophyll cycle and of the antioxidative scavenging system might account for enhanced PSI and PSII inhibition in vivo


1997 ◽  
Vol 129 (2) ◽  
pp. 205-217 ◽  
Author(s):  
T. M. DAVISON ◽  
W. N. ORR ◽  
B. A. SILVER ◽  
R. G. WALKER ◽  
F. DUNCALFE

The phosphorus fertilizer requirements and long term productivity of nitrogen-fertilized Gatton panic (Panicum maximum cv. Gatton) pastures, grazed by lactating dairy cows, were evaluated over 7 years. Cows grazed at 2·6 cows/ha on pastures that received annually 100 or 300 kg N/ha at each of 0, 22·5 or 45 kg P/ha. Phosphorus treatments were applied as single superphosphate, balanced for calcium by applications of gypsum.The soil had an initial available soil phosphorus content of 40 mg/kg (bicarbonate extraction). At zero P fertilizer (0P), extractable soil P declined at the rate of 1·9 mg/kg each year; at 22·5P it was maintained close to the original level while at 45P it increased at 6·6 mg/kg each year. Increased P fertilizer caused significant (P<0·01) increases in plant P concentration from year 2 onwards. In years 6 and 7 there was significantly less green pasture and leaf on offer in 300N pastures at 0P than with 22·5P and 45P. There was no influence of rate of P fertilizer at 100N on pasture quantity on offer in any year. There were clear trends at 100N of decreasing total pasture and green dry matter (DM) on offer over the 7 years, but not at 300N.Cows at 300N consumed more leaf in the diet in autumn and winter than at 100N. Leaf was 55–60% of the diet in summer and autumn, but decreased to 21% (100N) and 37% (300N) in winter. Dead material in the diet was always higher at 100N. Pasture leaf percentage and leaf yield were the best individual predictors of leaf percentage in the diet. Diet P selected from pasture was reduced by the higher rate of N fertilizer in each season. Estimated P concentrations of the diet selected from pasture for summer, autumn and winter averaged 0·30, 0·38 and 0·28% DM for 100N and 0·19, 0·24 and 0·18% DM for 300N treatments, respectively.The response to P fertilizer was dependent on the rate of N fertilizer applied. The critical bicarbonate extractable soil P level for this soil type, below which pasture responses occurred, was 30 mg/kg at 300N. The critical level at 100N was not reached, but was <23 mg/kg P.


Author(s):  
S. Errico ◽  
S. Dimatteo ◽  
S. Moliterni ◽  
F. Baldacchino

Insects are an emergent source of proteins in the world nutrition, both for humans and farmed animals, moreover they represent a novel food in Europe. The interest in Tenebrio molitor (L.) has particularly grown because its larvae are very rich of high biological value proteins. Although rearing of T. molitor has lately increased, the long-time conservation of alive larvae, very useful for both production and research, needs more information. Research studies conducted so far have investigated the reactions to low temperature on mealworms pupae and adults, or on larvae at 10 °C and for no more than 48 h. The aim of this study is to test the long-term effects of different times of cold storage at 10 °C on the larval survival and on the ability to become healthy adults and to potentially reproduce normally. The insects, divided in experimental groups, were refrigerated on sterile bran (and 10% of yeast) at 10±1 °C and 63% RH for 4 different periods of storage, from 30 to 120 days. Larval survival (i.e. number of larvae alive and number of pupae, expressed as a percentage), weight gain and presence of pupae were detected at the end of each period. The ability to complete the cycle was assessed by detecting the number of hatched pupae, deformed and well-formed adults. Our research results point out the possibility to store T. molitor alive larvae for long time (at least 120 days) at low temperature without significant negative effects on their ability to survive, with a relatively small loss (15.81%) and a very small percentage of deformed adults (4.07%). Further researches will be carried out to test the fertility of the well-formed adults and their ability to reproduce.


2007 ◽  
Vol 34 (10) ◽  
pp. 907 ◽  
Author(s):  
Shu-Hua Yang ◽  
Li-Jun Wang ◽  
Shao-Hua Li ◽  
Wei Duan ◽  
Wayne Loescher ◽  
...  

To study the UV-B effect on photosynthesis in winter wheat at different day/night temperatures, biologically effective UV-B radiation at 4.2 (LUVB) and 10.3 (HUVB) kJ m–2 d–1 was provided on the seedlings at 25/20°C or 10/5°C. UV-B radiation inhibited net photosynthesis rate (Pn) by enhanced intensity and decreased temperature without change of intercellular CO2 concentrations (Ci). Decreased maximal quantum yield of Photosystem II (Fv/Fm) and increased minimum fluorescence (Fo) were observed in HUVB at both temperatures and LUVB at 10/5°C. HUVB increased total pool size (VAZ) of xanthophyll cycle pigments, but decreased the de-epoxidation state (DEPS) of these pigments at both temperatures, while LUVB only decreased DEPS at 10/5°C. The activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) and the redox states of ascorbate and glutathione (AsA/DAsA and GSH/GSSG) were enhanced at 25/20°C, while there were increased SOD and CAT, unaltered APX activities and AsA/DHA, as well as decreased GR activity and GSH/GSSG in LUVB and HUVB at 10/5°C. UV-B radiation resulted in higher H2O2 and thiobarbituric acid reactive substance (TBARS) concentrations at 10/5°C than 25/20°C. It appears that low temperature alone did not influence photosynthesis but aggravated UV-B induced photoinhibition, which was associated with PSII photochemistry rather than stomatal limitation. Xanthophyll cycle pigments failed to provide photoprotection through thermal dissipation. The antioxidant system was up-regulated in LUVB and HUVB at 25/20°C, but was impaired at 10/5°C. Low temperature intensified UV-B induced photoinhibition and damage by weakening the antioxidant system.


2018 ◽  
Vol 19 (8) ◽  
pp. 2416 ◽  
Author(s):  
Agnieszka Płażek ◽  
Franciszek Dubert ◽  
Przemysław Kopeć ◽  
Michał Dziurka ◽  
Agnieszka Kalandyk ◽  
...  

In this article, the effects of cold on the development of Lupine angustifolius and the possibility of mitigating it, via seed hydropriming or pre-treatment with butenolide (10−6 M–10−4 M), are investigated in two cultivars, differing in their ability to germinate at low temperature. Physiological background of plant development after cold stress was investigated in imbibed seeds. For the first four weeks, the seedlings grew at 7 °C or 13 °C. Seeds well germinating at 7 °C demonstrated higher activity of α-amylase and higher levels of gibberellins, IAA and kinetin. Germination ability at low temperature correlated with dehydrogenase activity and membrane permeability. Seed pre-treatment improved germination at low temperature by decreasing abscisic acid content. Seed hydropriming alleviated cold effects on plant development rate and yield, while butenolide accelerated vegetative development but delayed the generative phase. Potential seed yield may be predicted based on the seed germination vigour and the photosynthetic efficiency measured before flowering.


PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246950
Author(s):  
Britta Dobenecker ◽  
Sven Reese ◽  
Sarah Herbst

Background The impact of dietary phosphorus (P) excess, especially on renal and cardiovascular health, has been investigated in several species, but little is known in dogs. Objective The aim of this study was to examine effects of different P sources on concentration and postprandial kinetics of selected parameters of P homeostasis in dogs. Methods Eight beagles received one control diet (P 0.5% dry matter [DM]) and three high P diets (poultry meal, NaH2PO4, and KH2PO4; P 1.7% DM) for 18d. Urine samples were collected pre- and postprandially while faeces were collected quantitatively for 5d and analysed for minerals. On day 18, blood was sampled 1h pre- and 0.5, 1, 1.5, 2, 3, 5 and 7h postprandially. Results Pi (KH2PO4, NaH2PO4) but not organic P caused an increased apparent P digestibility and significantly influenced kinetics of serum FGF23, parathyroid hormone, P, CrossLaps and bonespecific alkaline phosphatase, demonstrating a disrupted calcium (Ca) and P homeostasis with potential harm for renal, cardiovascular and skeletal health. Conclusions Results of feeding Pi to dogs indicate distinct disturbances of Ca and P metabolism, in contrast to organic sources. The use of Pi in food can therefore not be considered as safe. Further research, especially on dose and long-term effects, is warranted.


Author(s):  
Chong Zhao ◽  
Xiaofei Tian ◽  
Ping Sun ◽  
Lunchao Hu ◽  
Wenping Feng ◽  
...  

The increasing market demand for Glyptocidaris crenularis shapes its great potential for aquaculture. Temperature is an important factor affecting gonad production and quality of sea urchins. Therefore, it is essential and valuable to carry out an evaluation of the temperature effects on gonad production and quality in G. crenularis before potential aquaculture. Here, we investigated the long-term effects of temperature on gonad production, colour and flavour in G. crenularis. There was no significant difference of test diameter, height and body weight between the sea urchins in high (16–23°C) and low (12–16°C) temperatures (P > 0.05). Glyptocidaris crenularis showed significantly higher gonad production and index in high temperature and in low temperature (P < 0.05). L*, a*, b* readings were slightly higher in the low temperature groups, although no significant difference was found (P > 0.05). Subjective colour and flavour ratings found that G. crenularis in the low temperature group showed significantly better colour (P = 0.003) and flavour (P < 0.001) than those in the high temperature group. The present study provides valuable and insightful information into the establishing G. crenularis aquaculture.


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