Enhancing the cyclodextrin production by synchronous utilization of isoamylase and α-CGTase

Cyclodextrins (CD) are cyclic α-1,4-glucans composed of glucose units, and they have multiple applications in food, pharmaceuticals, cosmetics, agriculture, chemicals, etc. CD are usually produced by cyclodextrin glycosyltransferase (CGTase) from starch. In the present study, a simultaneous conversion approach was developed to improve the yield of CD from starch by conjunction use of isoamylase with α-CGTase. The isoamylase of Thermobifida fusca was cloned and expressed in Escherichia coli BL21(DE3). The biochemical characterization of the enzyme showed that the optimum temperature and pH of the recombinant enzyme was 50 °C and 5.5, respectively, and it maintained 60 %, 85 % and 78 % relative activity at 30 °C, 40 °C and 60 °C, respectively. When the recombinant isoamylase and α-CGTase were used simultaneously to convert potato starch (15 %, w/v) into CD, the optimum conditions were found to be: 10 U of α-CGTase and 48 U of isoamylase per gram of substrate, with reaction temperature of 30 °C and pH 5.6. On the optimum condition, the total yield of CD reached 84.6 % (w/w) after 24 h, which was 31.2 % higher than transformation with α-CGTase alone. This is the first report of synchronous bioconversion of CD by both α-CGTase and isoamylase, and represents the highest efficiency of CD production reported so far.     

Changes in color and texture of wheat noodles during chilled storage

Wheat noodles cooked for different periods of time were stored at 5 °C, and color changes in their cross sections were quantitatively assessed by digital image analysis. The color of noodles with flattened moisture distributions whitened greatly during the early stages of chilled storage due to the retrogradation of starch, with the color change showing a significant correlation with the changes in noodle fragility. Color changes were also measured for wheat noodles and noodles containing modified starch with internal moisture distributions, and local changes within the noodles were kinetically analyzed. The addition of modified starch significantly reduced the color change in the noodle interior, where the moisture content was relatively low. Scanning calorimetric measurements indicated differences in the gelatinized state of modified starch and original wheat starch at low moisture contents, which affected the rate of color change in the interior of noodles containing modified starch.     

Effects of different heat–moisture treatments on the physicochemical properties of brown rice flour

We evaluated the effect of heat–moisture treatment (HMT) on the main chemical components, physical properties, and enzyme activities of two types of brown rice flour: high-amylose Koshinokaori and normal-quality Koshiibuki. Five different HMTs using brown rice (moisture content was 12.0%) were assessed: 0.1 MPa/120 °C for 5 or 10 min, 0.2 MPa/134 °C for 5 or 10 min and 0.3 MPa/144 °C for 10 min. HMT, decreased the α-amylase and lipase activities, and fat acidity, and slightly increased the dietary fiber and resistant starch levels. After 2 months’ storage at 35 °C, rice samples that were treated with 0.2 MPa/134 °C or 0.3 MPa/144 °C for 10 min had a lower fat acidity than untreated samples, which would be useful for long-term storage and export of rice flour. And HMT exhibited inhibition of retrogradation in the pasting and physical properties, which is profitable to promote the qualities of the rice products.     

Cryopreservation of the common carotid artery of the rabbit: Optimization of dimethyl sulfoxide concentration and cooling rate

This paper describes the continuation of studies that demonstrated the suitability of CP-Tes solution as a medium for the introduction and removal of dimethyl sulfoxide in rabbit common carotid arteries and established the kinetics of cryoprotectant permeation in that tissue. In this paper we report the tolerance of rabbit common carotid artery to dimethyl sulfoxide, in concentrations up to 30% (w/w), using a technique of exposure that was designed to control osmotic stress. The maximum concentration achieved without damage was 15% (w/w). Vessels were then equilibrated with 15% dimethyl sulfoxide and cooled to −80 °C at 0.22, 0.69, 2.15, or 9.63 °C/min: they were then transferred to the gas phase of a liquid nitrogen refrigerator {temperature below −160 °C) for storage. Thawing was carried out in a 37 °C water bath. The optimum rate of cooling for these conditions was found to be 0.69 °C/min. The maximal recovery of contractile force in response to 10⁻⁶ M norepinephrine was 30–40%; relaxation to acetylcholine (an endothelium-mediated function) was 80% of control, and an estimated 71% of endothelial cells survived with minimal ultrastructural change.     

The deterioration of <Emphasis Type="Italic">Moringa oleifera</Emphasis> Lam. seeds in the course of storage involves reserve degradation

Seed deterioration in the course of storage may involve hydrolytic reactions. Hence, we aimed to evaluate viability, vigour, contents of reserves and metabolites, and activities of hydrolytic enzymes in Moringa oleifera Lam. seeds during storage under controlled conditions. Seeds were packaged in semipermeable plastic and maintained in a growth chamber (27 ± 2 °C and RH 60–65%) and under refrigeration (4 ± 2 °C and RH 20–25%) for 18 months. Samples were taken at the start of the experiment and every 3 months. During the first 12 months, water content, viability, and vigour remained almost unaffected, while the content of neutral lipids, starch, soluble sugars and free amino acids did not reduce in the seeds kept under refrigeration. After this period, the loss of viability and vigour was accompanied by the degradation of storage lipids, storage proteins, and non-reducing sugars associated with the increase of lipase and acid protease activity in both environmental conditions. As the seed water content remained below 8% in the course of the experiment, we suggest that non-enzymatic hydrolysis might play a role in the deterioration of M. oleifera seeds during storage. At least for planting, we recommend that M. oleifera seeds be kept at low relative humidity under refrigeration for up to 12 months.     

Selection and characterization of a newly isolated thermotolerant Pichia kudriavzevii strain for ethanol production at high temperature from cassava starch hydrolysate

Pichia kudriavzevii DMKU 3-ET15 was isolated from traditional fermented pork sausage by an enrichment technique in a yeast extract peptone dextrose (YPD) broth, supplemented with 4 % (v/v) ethanol at 40 °C and selected based on its ethanol fermentation ability at 40 °C in YPD broth composed of 16 % glucose, and in a cassava starch hydrolysate medium composed of cassava starch hydrolysate adjusted to 16 % glucose. The strain produced ethanol from cassava starch hydrolysate at a high temperature up to 45 °C, but the optimal temperature for ethanol production was at 40 °C. Ethanol production by this strain using shaking flask cultivation was the highest in a medium containing cassava starch hydrolysate adjusted to 18 % glucose, 0.05 % (NH₄)₂SO₄, 0.09 % yeast extract, 0.05 % KH₂PO₄, and 0.05 % MgSO₄·7H₂O, with a pH of 5.0 at 40 °C. The highest ethanol concentration reached 7.86 % (w/v) after 24 h, with productivity of 3.28 g/l/h and yield of 85.4 % of the theoretical yield. At 42 °C, ethanol production by this strain became slightly lower, while at 45 °C only 3.82 % (w/v) of ethanol, 1.27 g/l/h productivity and 41.5 % of the theoretical yield were attained. In a study on ethanol production in a 2.5-l jar fermenter with an agitation speed of 300 rpm and an aeration rate of 0.1 vvm throughout the fermentation, P. kudriavzevii DMKU 3-ET15 yielded a final ethanol concentration of 7.35 % (w/v) after 33 h, a productivity of 2.23 g/l/h and a yield of 79.9 % of the theoretical yield.     

Starch-sugar interconversion in Solanum tuberosum

The changes in starch, sugars, and respiration of both immature and mature potato tubers (variety King Edward) caused by transfer from +10° to +2° and back to +10°, were followed throughout. At each storage temperature the tubers were allowed to reach a steady state before transfer to another temperature. In potatoes transferred from +10° to +2°, the sugar at first rose rapidly and then reached a constant value after 30 days. The respiration showed a characteristic pattern, for the first 5–8 days being below the initial value, then rising to a maximum at 14 days and finally returning to the initial value at 28 days. In potatoes transferred from +2° to +10° the sugar declined steadily, the respiration reaching a maximum after 10 days and then slowly falling to a value slightly above the initial value. Quantitative analysis of the results showed that the sum of starch + sugar + CO₂ expressed in equivalent anhydrohexose units did not change throughout the various changes in temperature. This work provided a quantitative experimental basis for what had hitherto been an assumption. Starch was the only polysaccharide involved in these carbohydrate changes. No change in the amylose/amylopectin ratio was detected either during the breakdown of starch (temperature change +10° to +2°) or during its synthesis (+2° to + 10°). The increased respiration which accompanied any change in temperature was related quantitatively to the formation of sucrose from starch (+10° to +2°) and starch from sugar (+2° to + 10°). The ATP equivalent of the extra CO₂ output was of the same order as that predicted on the basis of known biochemical pathways linking starch and sugar.     

Prior frozen storage enhances the effect of edible coatings against Listeria monocytogenes on cold-smoked salmon during subsequent refrigerated storage

Aims: Listeria monocytogenes is a major safety concern for ready‐to‐eat foods. The overall objective of this study was to investigate whether prior frozen storage could enhance the efficacy of edible coatings against L. monocytogenes on cold‐smoked salmon during subsequent refrigerated storage. Methods and Results: A formulation consisting of sodium lactate (SL, 1·2–2·4%) and sodium diacetate (SD, 0·125–0·25%) or 2·5% Opti.Form (a commercial formulation of SL and SD) was incorporated into each of five edible coatings: alginate, κ‐carrageenan, pectin, gelatin and starch. The coatings were applied onto the surface of cold‐smoked salmon slices inoculated with L. monocytogenes at a level of 500 CFU cm^?2. In the first phase, the slices were first frozen at ?18°C for 6 days and stored at 22°C for 6 days. Alginate, gelatin and starch appeared to be the most effective carriers. In the second phase, cold‐smoked salmon slices were inoculated with L. monocytogenes, coated with alginate, gelatin or starch with or without the antimicrobials and stored frozen at ?18°C for 12 months. Every 2 months, samples were removed from the freezer and kept at 4°C for 30 days. Prior frozen storage at ?18°C substantially enhanced the antilisterial efficacy of the edible coatings with or without antimicrobials during the subsequent refrigerated storage. Conclusions: Plain coatings with ≥2 months frozen storage and antimicrobial edible coatings represent an effective intervention to inhibit the growth of L. monocytogenes on cold‐smoked salmon. Significance and Impact of the Study: This study demonstrates the effectiveness of the conjunct application of frozen storage and edible coatings to control the growth of L. monocytogenes to enhance the microbiological safety of cold‐smoked salmon.     

The effect of heat stress on skeletal muscle contractile properties

An elevated heat-shock protein (HSP) content protects cells and tissues, including skeletal muscles, from certain stressors. We determined if heat stress and the elevated HSP content that results is correlated with protection of contractile characteristics of isolated fast and slow skeletal muscles when contracting at elevated temperatures. To elevate muscle HSP content, one hindlimb of Sprague–Dawley rats (21–28 days old, 70–90 g) was subjected to a 15 min 42 °C heat-stress. Twenty-four hours later, both extensor digitorum longus (EDL) and soleus muscles were removed, mounted in either 20 °C or 42 °C Krebs-Ringer solution, and electrically stimulated. Controls consisted of the same muscles from the contra-lateral (non-stressed) hindlimbs as well as muscles from other (unstressed) animals. Isolated muscles were twitched and brought to tetanus every 5 min for 30 min. As expected, HSP content was elevated in muscles from the heat-stressed limbs when compared with controls. Regardless of prior treatment, both EDL and soleus twitch tensions were lower at 42 °C when compared with 20 °C. In addition, when incubated at 42 °C, both muscles showed a drop in twitch tension between 5 and 30 min. For tetanic tension, both muscles also showed an increase in tension between 5 and 30 min when stimulated at 20 °C regardless of treatment but when stimulated at 42 °C no change was observed. No protective effect of an elevated HSP content was observed for either muscle. In conclusion, although heat stress caused an elevation in HSP content, no protective effects were conferred to isolated contracting muscles.     

Debranching enzyme concentration effected on physicochemical properties and α-amylase hydrolysis rate of resistant starch type III from amylose rice starch

The effect of debranching enzyme concentration on physicochemical properties and α-amylase hydrolysis rate of resistant starch type III from high amylose rice starch were studied. The pullulanase enzyme (8, 10, 12, 14 and 16 U/g starch) was introduced to modify amylopectin molecules of 15% (w/w) gelatinized rice starches at 55 °C for 16 h. The debranched starches with different degrees of hydrolysis (0.14–5.27%), and having 66.60–98.82% β-amylolysis limit were then induced at 4 °C for 16 h, afterward a one cycle of freeze–thaw process (?10/30 °C) was applied. The results showed that a pullulanase hydrolysis improved the degree of syneresis (51.64–54.85% from 8 to 16 U/g starch). Resistant starch content increased sharply as the amount of the enzyme increased, reaching the highest (19.81%) for a 12 U/g starch and decreased to 13.16% by 16 U/g starch. α-Amylase hydrolysis rate showed that incompletely-debranched had a lower estimated glycemic index than completely debranched rice starches. Microstructure of the selected RS III samples using X-ray diffraction and scanning electron microscopy revealed a crystal pattern change from A- to V-type pattern and formed a coarse honeycomb-like and a filamentous network structure.     

In vitro conservation of Mandevilla moricandiana (Apocynaceae): short-term storage and encapsulation–dehydration of nodal segments

In vitro conservation of Mandevilla moricandiana was performed by slow-growth storage and encapsulation–dehydration. For slow-growth storage, half- and full-strength Murashige and Skoog (MS) medium and Woody Plant Medium, with or without sorbitol, mannitol, or glucose, were used to test the development of nodal segments and maintenance of plant viability after 6 mo. Recovery was performed using MS medium. The basal medium and carbon source did not interact, and only the carbon source had a significant effect on slow-growth storage and recovery. Sorbitol and glucose, individually or in combination, promoted development of plants with a low multiplication rate during the slow-growth period and a high multiplication rate during the recovery period. For encapsulation–dehydration, nonencapsulated and sodium alginate-encapsulated nodal segments were evaluated to determine their viability after storage at different temperatures. Nonencapsulated nodal segments gave 16.6% recovery after 60 d at 25°C. The effects of preculturing encapsulated nodal segments in MS medium with 0.4 or 0.75 M sucrose followed by dehydration were also tested. Capsules precultured for 48 h in the presence of 0.40 M sucrose and dehydrated to 40% moisture content showed 93.3% recovery. These conditions were then used to store capsules under different temperatures and for different lengths of time. The precultured capsules showed ca. 30% recovery after storage for 30 d at 4°C. Well-developed plantlets regenerated from encapsulated, stored nodal segments were rooted and acclimatized successfully, with 100% survival.     

Participation of GA3, ethylene,NO and HCN in germination of Amaranthus retroflexus L. seeds with various dormancy levels

Amaranthus retroflexus seeds were dormant at 25 °C in the darkness and in the light, and also at 35 °C in the darkness. GA₃ and ethylene partially removed dormancy at 35 °C in the darkness and at 25 °C in the light. Dormancy was removed by 1–5 days of treatment with nitric oxide or cyanide. The effect of NO and HCN was inhibited by cPTIO, thus the effect of HCN was NO dependent. Dry storage for 16 weeks could partially release dormancy only at 35 °C, but not at 25 °C. Dry storage increased the response to light, GA₃ and ethylene. The response to GA₃ and ethylene at 25 °C was enhanced with increasing storage temperature. GA₃, ethylene and nitric oxide could substitute dry storage and stratification in partially dormant seeds.     

The impact of temperature on the production and fitness of microsclerotia of the fungal bioherbicide Mycoleptodiscus terrestris

The impact of growth temperature was evaluated for the fungal plant pathogen Mycoleptodiscus terrestris over a range of temperatures (20–36°C). The effect of temperature on biomass accumulation, colony forming units (cfu), and microsclerotia production was determined. Culture temperatures of 24–30°C produced significantly higher biomass accumulations and 20–24°C resulted in a significantly higher cfu. The growth of M. terrestris was greatly reduced at temperatures above 30°C and was absent at 36°C. The highest microsclerotia concentrations were produced over a wide range of temperatures (20–30°C). These data suggest that a growth temperature of 24°C would optimize the parameters evaluated in this study. In addition to growth parameters, we also evaluated the desiccation tolerance and storage stability of air-dried microsclerotial preparations from these cultures during storage at 4°C. During 5 months storage, there was no significant difference in viability for air-dried microsclerotial preparations from cultures grown at 20–30°C (>72% hyphal germination) or in conidia production (sporogenic germination) for air-dried preparations from cultures grown at 20–32°C. When the effect of temperature on germination by air-dried microsclerotial preparations was evaluated, data showed that temperatures of 22–30°C were optimal for hyphal and sporogenic germination. Air-dried microsclerotial preparations did not germinate hyphally at 36°C or sporogenically at 20, 32, 34, or 36°C. These data show that temperature does impact the growth and germination of M. terrestris and suggest that water temperature may be a critical environmental consideration for the application of air-dried M. terrestris preparations for use in controlling hydrilla.     

Effect of freezing and freeze-drying on the viability and storage of Lilium longiflorum L. and Zea mays L. pollen

The freeze-preservation of pollen is dependent on the interaction of several factors such as freezing rate, thawing rate, freeze-drying temperature and duration, storage temperature and environment and rehydration rates. Changes in any of these variables affects the others directly or indirectly.Rapid freezing of pollen at rates of approximately 200 °C/min maintains the highest degree of viable pollen in combination with rapid thawing rates of 218 °C/min. Rapid cooling and slow rewarming resulted in a substantial loss of pollen viability. This might indicate that intracellular ice crystals formed during rapid cooling perhaps grow into larger ice masses during slow rewarming or storage at temperatures above ?50 °C.The germinability of pollen freeze-dried at temperatures below ?50 °C was also prolonged over that of the controls. Germination values for unfrozen pollen stored for 30 days at 0–5 °C averaged 50% for lily and 20% for corn. Freeze-dried pollen stored for 30 days at the same temperature yielded considerably higher viability percentages for both lily and corn pollen. Drying time is an important factor, perhaps indicating that residual moisture is critical. Freeze-dried pollen can be stored at higher temperatures than frozen and control pollen. Freeze-dried material stored for five months at 0–5 °C, upon slow rehydration yielded intact grains which has average germination percentages of 25 for lily and 15 for corn. The same pollen upon rapid rehydration showed rupturing of 20–40% of the cells and practically no germination.     

Effect of preservation of human semen sample at 4–6 and 25 °C on sperm motility

Sperm motility is the result of transverse movements that exist along its tail. It plays an important role in male fertility. The aim of this study was to evaluate the influence of keeping washed normozoospermic semen samples at 4–6 and 25 °C on the motility of spermatozoa. 26 semen samples of normozoospermic were washed twice in modified Ham’s F10 medium. Then, thirteen of the semen samples were kept in refrigerator (4–6 °C) and the remaining samples were stored in incubator (25 °C) for 12 days. On the 0 (immediately after sampling as control group), 1st, 2nd, 5th, 7th and the 12th days, the percentage of fast progressive (grade a), slow progressive (grade b), non-progressive (grade c) and immotile (grade d) sperm cells were calculated for each temperature. The data obtained from this study showed that the percentages of a, b and c grades of motile spermatozoa were significantly decreased (p?<?0.001) during 12 days at the both temperatures but reduction of these percentages has a gentle slope at 4–6 °C. There was no motile sperm after 12 days of storage. This study suggests that motile spermatozoa could be retrieved up to 7 days after the storage of washed normozoospermic men semen samples at 4–6 and 25 °C. Also, there were no motile sperm cells 12 days after sampling.     

Recovery of cellulase activity after ethanol stripping in a novel pilot-scale unit

Recycling of enzymes has a potential interest during cellulosic bioethanol production as purchasing enzymes is one of the largest expenses in the process. By recycling enzymes after distillation, loss of sugars and ethanol are avoided, but depending on the distillation temperature, there is a potential risk of enzyme degradation. Studies of the rate of enzyme denaturation based on estimation of the denaturation constant K _D was performed using a novel distillation setup allowing stripping of ethanol at 50–65 °C. Experiments were performed in a pilot-scale stripper, where the effect of temperature (55–65 °C) and exposure to gas–liquid and liquid–heat transmission interfaces were tested on a mesophilic and thermostable enzyme mixture in fiber beer and buffer. Lab-scale tests were included in addition to the pilot-scale experiments to study the effect of shear, ethanol concentration, and PEG on enzyme stability. When increasing the temperature (up to 65 °C) or ethanol content (up to 7.5 % w/v), the denaturation rate of the enzymes increased. Enzyme denaturation occurred slower when the experiments were performed in fiber beer compared to buffer only, which could be due to PEG or other stabilizing substances in fiber beer. However, at extreme conditions with high temperature (65 °C) and ethanol content (7.5 % w/v), PEG had no enzyme stabilizing effect. The novel distillation setup proved to be useful for maintaining enzyme activity during ethanol extraction.     

Biological fitness of Trichoderma atroviride during long-term storage,after production in different culture conditions

Identification of the production and storage factors that affect conidium germination and bioactivity (fitness) will assist the success of biological control agents. Effects of culturing conditions on conidium fitness of Trichoderma atroviride LU132 were examined in different storage conditions over time. Abiotic factors (temperature, nutrients, water activity and pH) during production were studied. Conidia from the culturing regimes which resulted in greatest and least bioactivity against Rhizoctonia solani in dual culture were selected to assess effects of storage conditions on conidium fitness. Fitness of the test conidia was examined after storage at 30°C and at 0% or 50% relative humidity (RH) over 6 months. Fitness declined over time, and the decline was greater for 50% RH than 0% RH, probably through reduced metabolic activity of conidia during long-term storage. Stored conidia were probably affected by dehydration, temperature and other factors such as oxidation, before and during storage, and also by rehydration after storage. The greatest number of conidia and germination percentage resulted from production at 25°C, but greatest bioactivity resulted from those produced at 30°C. No significant effects on bioactivity were detected between the conidium production treatments C?:?N 5?:?1 and C?:?N 160?:?1, indicating that C?:?N ratio in culture medium is not important for conidium survival of T. atroviride.     

Comparative proteomic analysis of cold-induced sweetening in potato (Solanum tuberosum L.) tuber

Cold-induced sweetening is one of the major factors limiting the quality of fried potato products. To understand the mechanisms of protein regulation for cold-induced sweetening in potato tubers, a comparative proteomic approach was used to analyse the differentially expressed proteins both during control (25 °C, 30 days) and cold treatment (4 °C, 30 days) using two-dimensional gel electrophoresis. Quantitative image analyses indicated that there were 25 protein spots with their intensities significantly altered more than twofold. Of these proteins, 9 were up-regulated, 13 were down-regulated, 2 were absent, and 1 was induced in the cold-stored tubers. The MALDI-TOF/TOF MS analyses led to the identification of differentially expressed proteins that are involved in several processes and might work cooperatively to maintain metabolic homeostasis in tubers during low-temperature storage. The preponderance of metabolic proteins reflects the inhibition of starch re-synthesis and the accumulation of sugars in carbon fluxes, linking starch–sugar conversion. The respiration-related proteins suggest the transfer of respiratory activity from aerobic respiration to anaerobic respiration in the cold-stored tubers. The proteins associated with defence appear to protect the tuber cells from low-temperature stress. Some heat shock proteins that act as chaperones also displayed a differential expression pattern, suggesting a potentially important role in cold-stored tubers, although their exact contribution remains to be investigated. The proposed hypothetical model might explain the interaction of these differentially expressed proteins that are associated with cold-induced sweetening in tubers.     

Effect of 1-MCP and low-temperature storage on postharvest conservation of camu–camu

Camu–camu, a native fruit from the Amazon region, is a rich source of bioactive compounds. However, its intense metabolic activity and high-water content limit the fruit’s postharvest storage and marketing. The aim of this study, conducted in two parts, was to evaluate the effects of 1-MCP and storage temperature on the physiology and postharvest preservation of camu–camu fruit. In part 1 of the study, fruit harvested at maturity stage 3 were divided into groups: control, 1-methylcyclopropene (1-MCP; 900 nL L^?1; 12 h) and ethylene (1000 µL L^?1; 24 h) and were stored at 22?±?1 °C and 85?±?5% RH for 9 days. In part 2, fruit harvested at maturity stage 3 were stored at 5, 10, 15, 20, or 25?±?1 °C and 85?±?5% RH for 9 days. During storage, fruit were evaluated daily for decay, mass loss, respiratory activity, and ethylene production, and every 3 days they were evaluated for peel color, pulp firmness, soluble solids content, total titratable acidity, ascorbic acid, total chlorophyll, and total anthocyanins. Fruit treated with 1-MCP exhibited delayed ripening due to lower metabolic activity, as evidenced by delay to softening, reduced mass loss and no decay. Storage at 5 °C prevented ethylene production, mass loss, color changes, and maintained pulp firmness, while did not affect soluble solids content. The results indicated that storage of camu–camu fruit at 5 °C or at 25 °C following application of 900 nL L^?1 1-MCP were effective strategies to delay ripening and maintain fruit quality up to 9 days.     

The effect of seed conditioning,short-term heat shock and salicylic,jasmonic acid or brasinolide on sunflower (Helianthus annuus L.) chilling resistance and polysome formation

The aim of this study was to develop the method for increasing resistance of sunflower seedlings ‘Wielkopolski’ to chilling. Seeds were conditioned at 25 °C for 2 days in water to 15, 20 and 25 % moisture content or in salicylic or jasmonic acid in concentration of 10^?2; 10^?3 and 10^?4 M or brassinolide in concentration of 10^?6; 10^?8 and 10^?10–15 % moisture content. After 2 days of incubation the conditioned seeds were heat shocked at 45 °C for 0, 30, 60, 120 and 240 min and 5 mm seedlings were exposed to chilling at 0 °C for 21 days. The effectiveness of the methods was assessed by evaluation of roots growth in Phytotoxkit Microbiotest, changes in the activity of dehydrogenases, the integrity of the cytoplasmic membrane and formation of polysomes after seedling were returned to 25 °C for 72 h. Seeds were conditioned at 25 °C for 2 days in water to 15 % moisture content and then heat shocked at 45 °C for 2 h decreased chilling injury of seedlings expressed by subsequent growth of the roots, electrolyte leakage, dehydrogenases activity and polysomes formation. Application of heat shock of 45 °C for 2 h during seed conditioning additionally provided seedling protection against subsequent chilling conditions. Brasinolide, salicylic acid or jasmonic acid applied during seeds conditioning exhibited further beneficial effect on seedling resistance to chilling. The most pronounced effect was obtained due to seed conditioning to 15 % moisture content in solutions of brassinolide in concentration of 10^?8 M. After 2 days of imbibition treated in this way seeds were exposed to heat shock at 45 °C for 2 h. The role of physiological events in improvement of sunflower chilling tolerance are discussed.