Chilling Susceptibility Research Articles

Eggplant grafting on a cold-tolerant rootstock reduces fruit chilling susceptibility and improves antioxidant stability during storage.

Vegetable grafting has been increasingly evaluated to improve preharvest tolerance to biotic and abiotic stresses. However, very few studies have identified rootstock-scion combinations able to improve fruit shelf life and reduce the susceptibility to postharvest disorders. Herein, a purple eggplant scion (cv. Monarca) was grafted onto a cold-tolerant hybrid Solanum rootstock ('Java') and the changes in growth, quality, postharvest chilling tolerance, and antioxidant stability were evaluated. Eggplant grafting enhanced plant vigor and fruit growth rate, decreasing the time from set to harvest by 10-15%. Grafted eggplants had a thinner shape and lighter pulp color than the control. The rootstock-scion combination tested showed lower respiration (~60%), dry matter (~15-20%), and phenolic compounds contents (~15-20%) than eggplants from non-grafted plants. Grafting markedly improved fruit performance during postharvest storage. Remarkably, grafted eggplants showed much higher tolerance to chilling injury than the control did, evidenced by a reduction of surface scalds along with decreased softening and pulp browning. The trend in antioxidants found at harvest time was reversed after cold storage due to enhanced stability (20% and 100% for pulp and peel respectively) in fruit from grafted plants. Purple eggplant (cv. Monarca) grafting onto 'Java' hybrid rootstock modulated fruit growth, quality at harvest, and increased fruit chilling injury tolerance during storage. Grafting may be a bona fide strategy to induce phenotypic traits able to improve vegetable postharvest performance. © 2021 Society of Chemical Industry.

At-harvest fruit maturity affects sucrose metabolism during cold storage and is related to chilling injury in peach.

We investigated the effects of at-harvest maturity of 'YuLu' peach fruit on soluble sugar metabolism and their relationship with chilling injury susceptibility. Peaches were sorted into four maturity groups at harvest by I AD (index of the absorbance difference between 670 and 720nm) then stored at 5°C for 28days. Fruit quality parameters, flesh browning index, malondialdehyde (MDA) content, soluble sugar content, gene expression, and enzyme activities associated with sucrose metabolism were measured. The more mature fruit groups had significantly (p < 0.05) lower firmness, higher soluble solid content, a* values of background color, sorbitol and sucrose content at harvest. During the cold storage, the higher flesh browning index in the mature groups (M3 and M4) maybe due to the double stress of senescence and chilling injury because there was concomitant sharp increase in MDA content. However, the most immature at-harvest group (M1) had the significantly (p < 0.05) higher MDA content after 14days of cold storage, and a flesh browning index significantly (p < 0.05) higher than the M2 group (the next more mature group), late in the storage period. Moreover, the M1 group had lower sucrose content at postharvest and higher activities and transcript levels of sucrose degrading enzymes and lower levels of sucrose synthesis enzymes, which was responsible for the lower sucrose levels than M2 group during storage. It was concluded that the more immature peach fruit with lower sucrose content, have a higher chilling susceptibility than more mature fruit.

Application of phytohormones during seed hydropriming and heat shock treatment on sunflower (Helianthus annuus L.) chilling resistance and changes in soluble carbohydrates

The objective of this study was to analyze the mechanism of some physiological processes accompanying acquisition of sunflower (Helianthus annuus L.) chilling resistance due to seeds hydropriming in the presence of salicylic acid, jasmonic acid, 24-epibrassinolide followed exposition of seeds to short-term heat shock treatment. The seeds were hydroprimed at 25 °C in limited amounts of water or solution of salicylic or jasmonic acid at 10−2, 10−3 and 10−4 M concentration, 24-epibrassinolide at 10−6, 10−8 and 10−10 M concentration. The seeds were incubated for 2 days, subjected to short-term heat shock (45 °C, 2 h) and chilled for 21 days at 0 °C. Sunflower chilling susceptibility and physiological responses were evaluated according to the inhibition of radicle growth, the inhibition of the number of lateral roots formation, the activity of catalase and changes in soluble carbohydrates in seedlings developing for 72 h at 25 °C. Hydropriming and short-term heat shock application explicitly reduced inhibition of roots as well as lateral roots development by allowing the germinating seeds to recover from the growth-inhibiting effects of chilling. Seeds hydropriming in solutions containing salicylic acid, jasmonic acid and 24-epibrassinolide followed heat shock treatment additionally promoted the activity of catalase and sugars metabolism, which stimulated seedlings development and alleviated the decrease of Fv/Fm caused by chilling conditions. These beneficial effects contributed to increased resistance of sunflower seedlings to chilling stress. The present study demonstrated that the most profitable effect on reducing negative effect of chilling may be achieved by short-term heat shock applied during hydropriming in water supplemented with 24-epiBL (10−8 and 10−10 M) or salicylic acid (10−3 and 10−4 M).

The capacity to maintain ion and water homeostasis underlies interspecific variation in Drosophila cold tolerance.

Many insects, including Drosophila, succumb to the physiological effects of chilling at temperatures well above those causing freezing. Low temperature causes a loss of extracellular ion and water homeostasis in such insects, and chill injuries accumulate. Using an integrative and comparative approach, we examined the role of ion and water balance in insect chilling susceptibility/ tolerance. The Malpighian tubules (MT), of chill susceptible Drosophila species lost [Na+] and [K+] selectivity at low temperatures, which contributed to a loss of Na+ and water balance and a deleterious increase in extracellular [K+]. By contrast, the tubules of chill tolerant Drosophila species maintained their MT ion selectivity, maintained stable extracellular ion concentrations, and thereby avoided injury. The most tolerant species were able to modulate ion balance while in a cold-induced coma and this ongoing physiological acclimation process allowed some individuals of the tolerant species to recover from chill coma during low temperature exposure. Accordingly, differences in the ability to maintain homeostatic control of water and ion balance at low temperature may explain large parts of the wide intra- and interspecific variation in insect chilling tolerance.

Changes in carbohydrate content in zucchini fruit (Cucurbita pepo L.) under low temperature stress

The postharvest handling of zucchini fruit includes low-temperature storage, making cold stress unavoidable. We have investigated the changes of soluble carbohydrates under this stress and its relation with weight loss and chilling injury in zucchini fruit during postharvest storage at 4°C and 20°C for up to 14 days. Two varieties with different degrees of chilling tolerance were compared: Natura, the more tolerant variety, and Sinatra, the variety that suffered more severe chilling-injury symptoms and weight loss. In both varieties, total soluble carbohydrates, reducing soluble carbohydrates and polyols content was generally higher during storage at 4°C than at 20°C, thus these parameters are related to the physiological response of zucchini fruit to cold stress. However, the raffinose content increased in Natura and Sinatra fruits during storage at 4°C and 20°C, although at 20°C the increase in raffinose was more remarkable than at 4°C in both varieties, so that the role of raffinose could be more likely related to dehydration than to chilling susceptibility of zucchini fruit. Glucose, fructose, pinitol, and acid invertase activity registered opposite trends in both varieties against chilling, increasing in Natura and decreasing in Sinatra. The increase in acid invertase activity in Natura fruit during cold storage could contribute in part to the increase of these reducing sugars, whose metabolism could be involved in the adaptation to postharvest cold storage.

Effect of heat conditioning on chilling injury susceptibility of Persian lime (Citrus latifolia Tanaka)

Effect of heat conditioning on chilling injury susceptibility of Persian lime (Citrus latifolia Tanaka)

The influence of oxygen on the inoculation process of cast iron

The role played by oxygen during the inoculation of cast iron was investigated. It was found that oxygen is not desirable when commercial and pure Ca inoculants are employed. Consequently, the cast iron exhibits inferior mechanical strength, with increasing chilling susceptibility and hardness. It is shown that depending on the degree of oxidation of the molten iron, CaC2, or CaC2-CaO mixtures are formed. The negative effect of oxygen in iron inoculation can be explained by its effect on reducing the likelihood of CaC2 formation. Relatively large contents of oxygen in the inoculated melt lead to a reduced cell count. Hence, under these conditions, high degrees of undercooling and relatively high chill tendencies are expected during the eutectic transformation.

Assessment of chilling injury during storage: chlorophyll fluorescence characteristics of chilling-susceptible and triazole-induced chilling tolerant basil leaves

Abstract Chlorophyll (Chl) fluorescence analysis by pulse-amplitude modulation (PAM) measurements was performed to assess the extent of chilling injury (CI) in stored sweet basil (Ocimum basilicum L.) leaves. Changes in three photosynthetic characteristics, in relation to visible CI rating, were monitored in leaves following modification of their chilling susceptibility by varying storage temperature and duration in two basil cultivars, or by soil application of triazole. Basil leaves developed severe or moderate visible symptoms of CI after 4 days of storage at 4 or 8 °C, respectively, but remained undamaged when stored at 12 °C. The chilling-dependent changes obtained in the ratios of variable to maximal fluorescence ( F v F m ), represented chilling sensitivity rather than membrane damage. The photochemical quenching coefficient (qP) was unaffected by low temperatures and did not seem to be correlated with CI. On the other hand, changes in the non-photochemical quenching coefficient (qNP) were positively correlated with the appearance of visual CI symptoms in leaves of the two cultivars at all storage temperatures and durations. Similarly, the chilling-alleviating effect of triazole was accompanied by a corresponding reduction in the chilling-induced decrease of qNP. Therefore, qNP may be associated with an irreversible transition step in the CI process, which precedes the appearance of visual symptoms. As such, changes in qNP may provide a suitable, rapid and non-destructive criterion for estimation of chilling damage in green tissues.

Effect of Preharvest Conditions on Chilling Susceptibility of Tomato Fruit

In a 2-year study, tomato plants (Lycopersicon esculentum Mill. cv. New Yorker), grown in field lysimeters, were subjected to water table levels (WTD) of 0.3, 0.6, 0.8, and 1.0 m from the soil surface, factorially combined with five K–Ca combinations, and replicated four times. Four mature green fruit per plant were stored at 5C for 21 days, and fruit color (L*,a*,b*) was measured daily. Fruit were then ripened at 21C for 10 days, and the surface area with chilling damage and the ripening stage noted for each fruit. In 1993, a dry year, the 1.0 m WTD showed the greatest color change, the 0.3 m WTD the least. The 1.0 m WTD showed the least damaged area and least delay in ripening, the 0.3 m WTD the most. In the wet year, 1994, differences by WTD were not significant. K and Ca fertilizer effects were not significant in either year. The number of hours below 15C, precipitation, and crop evapotranspiration in the week prior to harvest appeared to be of lesser importance than WTD in subsequent chilling response. Preharvest plant water relations appear to have some bearing on postharvest chilling sensitivity.

Seedling Development of Maize Genotypes at Constant and at Fluctuating Temperatures

AbstractFour maize genotypes from North West Europe, tropical highlands and tropical lowlands were grown at constant temperatures (14°C; 24°C), diurnal temperature variations (18°/10°C; 28°/20°C) and at temperatures alternating every three days (18°+ 10°C; 28°+ 20°C) until the three leaves stage. Fluctuating temperatures were generally favourable for growth with most marked effects at an average of 14°C when 18°/10°C were applied. Temperature situation had pronounced effects on morphological and biochemical traits like area of second leaves and activity of phosphofructokinase but between these traits and growth rates no close relationship existed. For all traits genotype specific reaction patterns to temperature situation existed. One tropical highland variety excelled by fast growth, especially at low fluctuating temperatures. A specific chilling susceptibility of the tropical lowland variety was only marked for growth at constant 14°C.

Primary Role of the Cytoplasmic Membrane in Thermal Acclimation Evidenced in Nitrate-Starved Cells of the Blue-Green Alga, Anacystis nidulans

The lipid phase transition of the cytoplasmic membrane and the chilling susceptibility were studied in nitrate-starved Anacystis nidulans cells. Nitrate starvation resulted in the disappearance of the thylakoid membrane system, without any effect on chilling susceptibility. The chilling susceptibility of the algal cells depended on the growth temperature. Temperatures of lipid phase transitions of the cytoplasmic membranes were detected by chilling-induced spectral changes in the carotenoid region, in vivo. These values were identical to those of cultures containing intact thylakoid systems. Our results suggest that cytoplasmic membrane plays a determinative role in the thermal acclimation of the alga cells.

Selective modification of cytoplasmic membrane fluidity by catalytic hydrogenation provides evidence on its primary role in chilling susceptibility of the blue-green alga, Anacystis nidulans

Cytoplasmic and thylakoid membranes were isolated at different stages of catalytic hydrogenation of fatty acyl double bonds in living cells of Anacystis nidulans. The reaction was limited to the lipids of cell-surface membranes during the initial period of hydrogenation, thus, we were able to produce alga cells, modified exclusively in the cytoplasmic membrane. In these unique cells, neither compositional nor physical changes were detected in the lipid phase of thylakoids. Due to the rigidification of the alkyl chains of its lipids, however, the cytoplasmic membrane became leaky and phase separated at considerably higher chilling temperatures.Since an irreversible inactivation of photosynthetic electron transport was found simultaneously, it provided direct evidence for the hypothesis that the thermotropic properties of the lipids within cytoplasmic membranes, and not those of the thylakoids, control chilling susceptibility of the blue-green alga, A.nidulans.

Modulation of membrane fluidity by catalytic hydrogenation affects the chilling susceptibility of the blue-green alga, Anacystis nidulans

All the changes, i.e. the phase separation temperature of thylakoid lipids, shift in the chilling induced increase of K + permeability and decline in photosynthetic O 2-production, respectively, brought about by temperature acclimation in Anacystis nidulans, can be accomplished by homogeneous catalytic hydrogenation of the fatty acids, as well, using a new water-soluble Pd(II) complex, hitherto unknown in biological applications. Since the thermo-adaptation replaced by proper hydrogenation conducted under isothermal condition results in a similar modification of chilling susceptibility, it afforts direct evidence that chilling response is mediated by changing the degree of fatty acid unsaturation in Anacystis nidulans.

A comparative study of low‐temperature‐induced ultrastructural alterations of three species with differing chilling sensitivities

Abstract. The effects of light and water stress upon chilling injury of chloroplasts have been assessed by electron microscopy in seedlings of three species known to differ in their chilling susceptibility. Chilling injury to chloroplasts was first manifested by distortion and swelling of thylakoids, reduction in starch granule size, and the formation of small vesicles of the envelope, called the peripheral reticulum. More prolonged treatment produced accumulations of lipid droplets, increased staining of the stroma, disintegration of the envelope, and mixing with cytoplasmic contents. Cotton, a notably chilling‐sensitive plant, and bush bean, a somewhat less sensitive plant, showed damage within 6 h when exposed to both light and water stress at chilling temperatures (5°C). Even collard, a chilling‐resistant species, exhibited signs of chilling injury to chloroplasts after 6 h when exposed to both light and water stress but the plastids remained intact throughout the 48 h of treatment. Comparable chilling injury does not occur in cotton until around 72 h if the plants are exposed to water stress or light separately. Bush bean was affected less by separate treatments of light and water stress. The least chilling injury occurred in all three species when they were kept in the dark at a high humidity.

Chilling Susceptibility of the Blue-green Alga Anacystis nidulans

Effects of chilling treatment on the photosynthetic activities and the light-absorption and fluorescence spectra were investigated in intact cells of the blue-green alga Anacystis nidulans that were grown at different temperatures. When the algal cells grown at 38 C were treated at 0 C for 10 minutes, the photosynthesis and the Hill reaction with 1,4-benzoquinone were significantly inactivated and the light-absorption spectrum of carotenoids was modified. These parameters showed very similar temperature dependencies in the chilling susceptibility and the temperature regions critical for the susceptibility depended on the growth temperature. The midpoint values for the critical temperature regions were 4, 6, and 12 C in cells grown at 28, 33, and 38 C, respectively. It is proposed that a common mechanism would underlie the chilling susceptibility of the photosynthesis, the Hill reaction, and the carotenoid absorption spectrum. The decoupling of excitation transfer from allophycocyanin to chlorophyll a at the chilling temperatures occurred very slowly and is attributed to a somewhat different mechanism of the chilling susceptibility.

Chilling Susceptibility of the Blue-green Alga Anacystis nidulans

Potassium ions and amino acids were found to leak from the cytoplasm to the outer medium when the blue-green alga, Anacystis nidulans, was exposed to the chilling temperatures. The leakage was marked below the critical temperature regions, the midpoint values for which were around 5 and 14 C in cells grown at 28 and 38 C, respectively. These temperature regions coincided with those critical for the susceptibility of the photosynthetic activities and the carotenoid absorption spectrum previously studied (Ono TA, N Murata 1981 Plant Physiol 67: 176-181).Potassium and magnesium ions in the cell suspension medium protected the algal cells from the chilling-induced damage of the Hill reaction with 1,4-benzoquinone. The activity of the Hill reaction which had been diminished by the first chilling treatment in a low salt medium was restored by the second chilling treatment of a high salt medium. The chilling susceptibility of the Hill reaction could be attributed to the leakage of cations from the cytoplasm due to increased permeability of the cytoplasmic membrane at the chilling temperatures.A mechanism is proposed to interpret the chilling susceptibility of A. nidulans: (a) at chilling temperatures, the bilayer lipids of the cytoplasmic membrane are in the phase separation state; (b) ions and solutes having low molecular weights leak from the cytoplasm to the outer medium when the lipids of the cytoplasmic membrane are in the phase separation state; (c) decreases in the intracellular concentrations of ions and solutes degrade the physiological activities of the cells.