Effect of temperature on the sugar content of potato callus tissue

The effects of temperature, incubation time, callus age, and growth regulator on the reducing and nonreducing sugars of Lemhi Russet callus grown on Murashige - Skoog medium with 3% sucrose were determined. Callus grown at 25°C for approximately 4 weeks (0 time) were held at 25°C or transferred to 15°C and 5°C for 4-week periods. Callus grown at 5°C for 4 weeks was transferred back to 25°C for a 4-week period to simulate reconditioning of potatoes. The reducing sugar content decreased rapidly with time at 25°C and 15°C when either 2,4-D or picloram was used as a growth regulator. At 5°C the reducing sugar content increased or decreased slightly, depending on the original reducing sugar content of the callus. The initial reducing sugar content at 25°C and the relative effect of 5°C incubation was dependent on the age of the callus tissue. Reducing sugars in 5°C callus were rapidly lost after reconditioning at 25°C. The nonreducing sugars exhibited similar overall changes as the reducing sugars, but the nonreducing sugar concentrations were much lower. Thus, potato callus cultures are similar to whole tubers insofar as they accumulate or maintain high reducing sugars at low temperatures and lose these sugars during reconditioning.     

The effect of 2,4-d on tuberization and starch content of potato tubers produced on stem segments culturedin vitro

The effect of 2,4-D on tuberization, yield and the starch content of potato tubers produced on stem segments was examined. Potato stem segments were cultured in nutrient agar containing 2,4-D concentrations ranging from 10^?7 M to 2 × 10^?3 M. The stem segments were incubated in the dark at 25° C and examined after 15 days. The degree of tuberization on stem segments cultured in media containing 10^?7 M and 10^?6 M 2,4-D was higher than on the control stem segments. Mainly long stolons were observed on stem segments cultured in media containing 10^?4 M and 2 × 10^?3 M 2,4-D. The percent starch (dry wt. basis) in stolons was higher than that in tubers. However, the total starch content of tubers per stem segment cultured in media containing 10^?7 M and 10^?6 M 2,4-D was significantly higher than that of stolons obtained from stem segments cultured in media containing higher concentrations of 2,4-D. The total starch content of tubers, except those produced on stem segments cultured in media containing 10^?7 M 2,4-D, decreased steadily with increasing concentration of 2,4-D in the culture media.     

Haploid Plantlet Production through Somatic Embryogenesis in Anther-Derived Callus of Bupleurum falcatum

Abstract

This study was carried out to verify the production of haploid plantlets through somatic embryogenesis of Bupleurum falcatum in anther culture (2n=16). Flowers with anthers at the uninucleate stage, less than 200 µm in anther length, were exposed to 10ºC for 5 days (cold pretreatment) and the anthers were cultured on MS medium supplemented with 2,4-D and/or picloram at various concentrations at 30ºC. The optimal supplement for callus formation was a mixture of 0.075 mg L-¹ 2,4-D + 0.075 mg L-¹ picloram or 0.75 mg L-¹ 2,4-D without picloram. Only a few calli were induced from the anthers without cold pretreatment. The calli were transplanted to MS medium without phytohormones and cultured at 25ºC for plant regeneration. Among one hundred twenty root tips of the regenerated plantlets examined, 14.2% were haploid (n=8). However, in the plantlets regenerated from anthers without cold pre-treatment only 2.5% was haploid. In both haploid and diploid regenerated plantlets, the chromosome number was fixed without variation. Among the regenerated plantlets, one was albino. Haploid plantlets were transplanted to the field after acclimation in pots filled with vermiculite under 90% humidity for a month, and haploid plant were produced. The potential of haploid plants derived from anther culture for production of high-yield and good-quality cultivars is discussed.     

Methods to increase the starch content of potato tuber callus tissue

Summary Attempts were made to increase the starch content of callus tissue from tubers of cvs Lemhi Russet and Russet Burbank by varying growth regulator concentration, sugar source, sugar concentration, temperature and callus shape. Starch content was always higher in media containing no growth regulators. Callus spread over the media contained more starch than unbroken rectangular or cube-shaped callus. Sucrose was superior to glucose and fructose for starch formation. A sucrose concentration of 20 % produced more starch than lower concentrations. Callus growth decreased as the sucrose concentration increased. ‘Lemhi Russet’ callus incubated with 8 % sucrose at 20, 25 and 30 °C contained 1.2, 0.4 and 0.8 % starch respectively, which was much higher than in ‘Russet Burbank’ callus. With varying amounts of mannitol as an osmoticum in 8 % sucrose, the most starch was found in the medium containing 5 % mannitol. Research Paper 92B2 of the Idaho Agricultural Experiment Station     

Effects of Physiological Status of Parent Plants and Culture Medium Composition on the Anther Culture of Sorghum

Abstract

Anthers at various maturation stages were collected from seven genotypes of Sorghum bicolor, and cultured on MS medium supplemented with 3 mg L^?1 2,4-D and 2.0 mg L^?1 kinetin. The rate of callus induction was high in young anthers, and decreased with maturation of the anther. Young anthers were collected from the plants grown in the greenhouse (greenhouse anthers), in the field (field anthers), and in the chambers kept at 20, 25 or 30 °C. Then they were cultured on MS medium containing 2.0 mg L^?1 kinetin, 1.0 mg L^?1 IAA and 2.5 mg L^?1 2,4-D, on which the rate of callus induction was the highest. The average callus-induction percentage was 6.4% in the field anthers, and 3.7% in the greenhouse anthers. Callus induction was low in the anthers collected from the plants grown at 30° C. Among the genotypes examined, TX403 produced calli at the highest frequency. The rate of plant regeneration from anther-calli was the highest on the medium containing 2.5 mg L^?1 kinetin and 3.0 mg L^?1 IAA. The regeneration rate of green plantlets on this medium was 27% on the average, and was 46.2 and 28.6% in PP290 and TX403, respectively. The chromosome number in root-tip cells was unstable, but was 20 in most of the regenerated plantlets.     

Effects of elevated growth temperature and carbon dioxide levels on some physicochemical properties of wheat starch

Crops of winter wheat (cv. Hereward) were grown in the field under double-skinned polyethylene tunnels in two consecutive seasons (1991–92 and 1992–93). Air containing ambient (350 ppm) or elevated (700 ppm) concentrations of carbon dioxide was circulated through the tunnels, and temperature gradients, typically from 1°C below ambient to 4–7°C above ambient, were maintained within each tunnel. Despite a shorter crop duration and warmer temperatures in the first season, most grain and starch properties showed a similar response to temperature between seasons. Thousand grain weight and grain starch content declined with increase in temperature (from 55±5 mg to 18±2 mg, and from 31±3 mg to 7±2 mg, respectively), the latter reflecting both decreases in granule sizes and fewer amyloplasts per endosperm. Contents of total amylose and lipid-free amylose increased with temperature (from 26±1% to 31±1%, and from 21±1% to 25±1%, respectively), but the contents of lipid-complexed amylose (5·2±1·5%) and lysophospholipids (0·9±0·2%) varied independently of temperature. Starch gelatinisation temperatures ranged from 57·5 to 64·5°C in the first season, and from 58·0 to 61·9°C in the second season, increasing with increase in temperature in both seasons, the data for the two seasons providing almost separate clusters. Gelatinisation enthalpy was constant in the first season (12·6±1 J/g amylopectin) and in the second season (15·5±0·5 J/g amylopectin) with no effect of temperature. The differences in carbon dioxide concentration had no consistent effects on the parameters measured, but small effects were discernible on thousand grain weight, starch content and lipid-free amylose content. There were also effects in certain treatment combinations, specifically at warmer temperatures in the first season and at cooler temperatures in the second season, on thousand grain weight, non-starch solids and lipid-complexed amylose contents.     

Protein,starch, and non-protein nitrogen accumulation in high protein hybrids and low protein cultivars

Tuber protein, starch, non-protein nitrogen and percent dry matter content were measured during tuber development of four Phureja-Tuberosum-Andigena hybrids and two Tuberosum cultivars. Percentages of starch and protein in the tuber dry matter were curvilinearly related to tuber size in all six clones. The amounts of starch and protein in a tuber were linear functions of tuber size. Rates of protein accumulation in some of the hybrids were higher than those of either cultivar. Starch accumulation rates were similar among all six clones. The high protein character of at least one of the hybrids was associated with starch containing storage tissue. Differences between high and low protein clones were mainly related to quantitative differences in the subunit composition of the protein. The ratio of non-protein nitrogen to protein N was similar among the six clones. Relationships between percent dry matter and starch content were not consistent among the six clones.     

Callogenic studies of Achyranthes aspera leaf explant at different hormonal combinations

With the objective to promote in vitro callus induction, leaf segments of Achyranthes aspera were inoculated on basal MS medium supplemented with 3.0% sucrose and 0.8% agar with different concentrations of 2,4-D alone and in combination with NAA, BAP, IAA, IBA and Zeatin. The explants were maintained in growth room at 25 +/- 1 degrees C and 16 h light cycle. The best callus induction was obtained with 2,4-D (1.0 and 2.0 mg L(-l)) in combination with NAA (0.5 mg L(-1)). Callus induction and good texture from leaf explant was also observed at 2,4-D with BAP. On these combinations morphologically, light green, soft, compact and non-embryogenic callus (Type III callus) was observed. While morphology of callus and callogenic response was poor at 2,4-D alone or in combination with other hormones at different concentrations.     

Potato top growth as influenced by temperatures

A study was conducted to establish a growth rate response of potato plant (Solanum tuberosum L.) tops to exposure to 72-hr periods of six constant temperature treatments (10, 15, 20, 25, 30, 35°C) and to determine a thermal optimum for vegetative potato growth rates. The plants were maintained under “no stress” soil moisture conditions throughout the study. The temperature treatments were accomplished by inserting the plants into a growth chamber for 72 hours at selected temperatures. Maximum growth (as measured by percent change in leaf area) occurred at 25°C with temperature growth differences significant at the 5% level. Plant height measurements (percent change occurring during treatment time) showed maximum stem elongation at 30°C during an early growth stage and 25°C during stage 2 (4 weeks later). Predictive models developed from the data indicate maximum rates of leaf area increase in both growth stages occur at 24.7°C and that maximum rates of stem elongation occur at 31.3 and 27.4°C for growth stages 1 and 2, respectively. Leaf water potential and stomatal resistance measurements taken at the end of each treatment period indicated that no water stress occurred.     

细胞分裂素对蝴蝶兰胚性愈伤组织诱导的影响

分别以6-Benzylaminopurine(6-BA)和2,4-Dichloro phenoxyacetic acid(2,4-D)诱导蝴蝶兰外植体.6-BA从嫩茎切块诱导出胚性愈伤组织,细胞富含淀粉粒,而2,4-D得到的愈伤组织不能分化.6-BA易于从嫩叶切片诱导胚性愈伤组织,进行体细胞胚发生过程的显微观察和代谢分析.6-BA诱导期间,DNA含量上升伴随胚性愈伤组织生长,水溶性蛋白变化稍延缓于RNA含量变化.培养第11天新出现12.13,13.08,66.30,97.25,104.31 ku蛋白质,可能与胚性细胞出现有关,第25天新出现40.87 ku蛋白质,与体细胞胚形成有关.     

农杆菌介导的小麦成熟胚遗传转化影响因素分析

为解决农杆菌介导的小麦成熟胚遗传转化效率较低的难题,以春小麦Bobwhite成熟胚为外植体,分析植物激素、愈伤组织预培养时间、侵染时间和共培养阶段干燥处理对小麦成熟胚愈伤组织遗传转化的影响,并在遗传转化处理中辅以3个组织再生相关基因(TaSERK1、TaSERK2、TaNiR)的qRT-PCR分析。结果表明,愈伤组织预培养阶段添加适量的2,4-D和Picloram均可诱导成熟胚愈伤组织的形成,但是2mg·L~(-1)Picloram培养基中愈伤组织的胚萌发率为20.78%,远高于2,4-D诱导的胚萌发率(11.38%);共培养阶段对农杆菌侵染的愈伤组织进行干燥处理能适当提高愈伤组织的转化效率;qRT-PCR分析发现再生相关基因TaNiR相对表达量的增加能适当提高愈伤组织的转化率。     

Potato chip color ratings of advanced selections from the Maine potato breeding program

Seven named varieties and three numbered selections from the University of Maine potato breeding program were compared for chip color at various conditions and lengths of storage. Although all selections tested were equal to or better than Kennebec in chip color, only Allagash Russet equaled Monona. Storage at 45° F (7.2° C) produced acceptable chip color at all time periods tested. After long term storage at 45° F, reconditioning at 55° F(12.8° C) was ineffective in improving chip color. Following storage at 38° F (3.3° C) acceptable chip color could be produced only by reconditioning at 70° F (21.1° C) for at least two weeks.     

Influence of post-harvest storage temperature and gamma irradiation on potato carotenoids

Summary A comparative study of nine Indian potato varieties showed a good correlation between their total carotenoid content and the tuber flesh colour. Regardless of varietal differences, carotenoid level showed an increase during storage at ambient temperature (25–30°C) and to a lesser extent at 2–4°C and 15°C. Tubers exposed to an irradiation dose of 10 krad for sprout inhibition showed decreased levels of carotenoids during storage, particularly at 15°C where 50% loss was observed after 6 months of storage. Irradiated tubers stored for seven months at 15°C, on reconditioning at 34–35°C for 6 to 12 days showed a 2- to 6-fold increase in their carotenoid content.     

Temperatures and ethanol effects on the properties of extruded modified starch

Temperature and blowing agent are major factors influencing the properties of extruded foam materials. This study was conducted to determine the influence of temperature and alcohol content on selected properties and molecular weight of acetylated starch foam. Starch acetate, with degree of substitution of three, was prepared from 70% amylose corn starch and extruded with either 16 or 18% (db) ethanol in a single screw extruder at either 120 or 160°C. Unit and solid densities, specific mechanical energy, compressibility, spring index, water absorption and water solubility indices, glass transition temperature, molecular degradation and degree of substitution (DS) of the starch were measured. The samples extruded at 120°C had lower spring indices and water absorption indices (WAI), but higher compressibility and unit density than acetylated starch extruded at 160°C. The samples extruded with 16% ethanol content on a dry basis had lower spring indices and higher WSI than samples extruded with 18% alcohol. The extruded samples had lower solid density, WSI and WAI as compared to non-extruded acetylated starch. A slight decrease in the average molecular weight was recorded as a result of the extrusion processing. The samples extruded at 160°C had high spring indices and low unit densities and thus were more suitable for use as a loose-fill packaging material.     

小麦淀粉的粒度分布、组分及糊化特性对氮硫肥的响应

为明确氮硫肥对小麦淀粉粒度分布及主要理化特性的影响,以强筋小麦品种西农9718和中筋品种陕农138为材料,采用不同氮硫肥水平进行处理,系统分析了小麦A、B淀粉的粒度分布、淀粉组成、膨胀势及糊化特性对氮硫肥的响应。结果表明,强筋和中筋小麦品种的淀粉粒度分布基本一致。A淀粉粒体积分布占总淀粉的74.95%～75.43%,但淀粉粒数量远少于B淀粉粒。A淀粉的直链淀粉、峰值黏度、低谷黏度、崩解值、最终黏度以及回生值高于B淀粉,而B淀粉有更高的支链淀粉、膨胀势和糊化温度。不同氮硫肥处理改变了小麦淀粉的粒度分布,进而影响淀粉的组成和糊化特性。在施氮(230kg.hm-2)条件下,强筋品种西农9718和中筋品种陕农138的A、B淀粉分别在硫肥施用量为46和56kg.hm-2时有较低的直链淀粉含量、较高的膨胀势及较好的糊化特性。陕农138淀粉的粒度分布、组成及糊化特性对氮硫肥的响应比西农9718更敏感。适当的氮、硫肥配施有利于改善小麦的淀粉品质。     

Investigation on morphological structure and crystal transition of maize starch gelatinized in pure glycerol

The gelatinization phenomena and crystalline structure of maize starch gelatinized in pure glycerol were investigated using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Starch granules were firstly treated in water system, CLSM and SEM micrographs displayed that they were completely broken and the characteristic birefringence of the starch granules disappeared at 70 °C. As for pure glycerol system, the starch granules swelled but maintained granular shape with the increasing of temperature. The crystalline structure of starch granules was partially destroyed at 130 °C and completely destroyed at 140 °C. The DSC thermogram showed that the gelatinization temperature of starch in glycerol started at 123.7 °C, peaked at 128.4 °C, and concluded at 135.2 °C. The X-ray diffractograms indicated that the crystalline structure of maize starch was partially destroyed at 130 °C and completely destroyed at 140 °C. Thus, glycerol served an alternative solvent to destroy crystalline structure of maize starch, which may be helpful for hydrolysis of starch granules by amylase in food industry.     

Some studies on carbohydrates in potato tubers

Summary Starch and pulp were isolated from three cultivars of potato tubers grown in four localities. The starch content in the pulp was determined by an enzymatic method which is shown to be more accurate than a polarimetric method. On an average, 94% of the starch was isolated and 5% remained in the pulp. The change in low-molecular weight carbohydrates in the potato tubers during storage for 2, 4, 7 and 11 weeks at 9 C was studied. Generally there was an increase of sucrose, glucose, fructose andmyo-inositol during the first 2–4 weeks of storage, followed by a diminishing decrease.     

Effects of Early- and Late-Sowing on Starch Accumulation and Associated Enzyme Activities During Grain Filling Stage in Rice

The environmental temperature occurring during the grain filling stage is an important factoraffecting starch synthesis and accumulation in rice. We investigated starch accumulation, amylaseactivity and starch granule size distribution in two low-amylose japonica rice varieties, Nanjing 9108 andFujing 1606, grown in the field at different filling temperatures by manipulating sowing date. The two ricevarieties exhibited similar performances between two sowing dates. Total starch, amylose andamylopectin contents were lower at the early-filling stage of T1 treatment (Early-sowing) compared withthose at the same stage in T2 treatment (Late-sowing). In contrast, at the late-filling stage, when fieldtemperatures were generally decreasing, total starch and amylopectin contents in T1 were highercompared to those in T2. The ideal temperature for strong activity of ADP-glucose pyrophosphorylaseand soluble starch synthase was about 22℃. A higher temperature from the heading to maturity stagesin T1 increased the activities of starch branching enzyme and suppressed the activities of granule boundstarch synthetase and starch debranching enzyme. We found that rice produced larger-sized starchgranules under the T1 treatment. These results suggested that due to the early-sowing date, the hightemperature (30℃) occurring at the early-filling stage hindered starch synthesis and accumulation,however, the lower temperatures (22 ℃) at the late-filling stage allowed starch synthesis and accumulationto return to normal levels.     

Modelling starch phase transitions and water uptake of rice kernels during cooking

To model the cooking processes of rice, starch gelatinization, the level of fusion of the amylose-lipid complex, and equilibrium water uptake have to be known for any given condition. Starch phase transitions were measured by DSC in two milled Korean round rice kernels whose water contents ranged from 0.18 to 4.7 g g⁻¹ db. Two to three partially overlapping transitions were assessed. Starch thermal transitions were modelled using a double step approach. First, a mechanistic double sigmoid model was fitted with DSC data for any water content value. Each parameter of the mechanistic model was then modelled with conservative empirical water content functions. In this way we obtained an explicit form of phase transition levels as a function of both temperature and water content. In parallel, the water uptake kinetics of rice kernels was determined in the temperature range of 50 °C–100 °C. Equilibrium water uptake was found to be linked to starch phase transitions and a model was built to calculate equilibrium water uptake as a function of modelled starch gelatinization and amylose-lipid complex fusion levels.