Tuber Starch Content Research Articles

Cassava (Manihot esculenta Crantz) Tuber Quality as Measured by Starch and Cyanide (HCN) Affected by Nitrogen, Phosphorus, and Potassium Fertilizer Rates

Cassava (Manihot esculenta Crantz) is an important subsistence crop for many poor rural families in Africa. Cassava contains cyanogenic glucosides (linamarin and lotaustralin) which liberate hydrogen cyanide (HCN) during tuber processing. Once liberated, HCN attaches to the processed tuber. Continuous consumption of processed tuber containing high HCN concentration coupled with low protein intake causes Konzo – a paralyzing disorder that impacts children and women of childbearing age. There are ways to reduce HCN concentration during tuber processing; however, this can also reduce the overall starch content in the cassava tuber. A study comprising twenty treatments consisting of different combinations of nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates was initiated in 2013 in the coastal Dondo District of Mozambique to assess cassava tuber quality as measured by starch and HCN. Significant differences were observed in starch content (CSC) of unprocessed tubers due to combined addition of N, P and K fertilizer rates, sample size, and estimation procedure. However, no significant differences were observed in HCN concentration in tubers due to the addition of N, P and K fertilizer. The HCN concentration in cassava tuber appears to be a function of the physiology of the crop or possibly cassava variety rather than the environment or conditions under which the crop is grown.

SENSORY AND TECHNOLOGICAL QUALITY OF SLOVAK VARIETIES OF EDIBLE POTATOES

This scientific work deals with technological and sensory quality examination of a set of nine Slovak potato varieties. Varietal samples were grown and stored at the Potato Research and Breeding Institute in Veľká Lomnica (Slovak Republic). Evaluated varieties: Arwen, Evelin, Malvína, Megan, Rumelia, Spinela, Svella, Timea, Viola. Dry matter and starch content of tubers were evaluated from the group of technological parameters. Sensory evaluation was carried out by using the dine value point descriptor. Varietal evaluation was realized from the harvest of 2011 and 2012.The highest dry matter content of 21.8% was measured at variety Rumelia. The starch content was at the same variety at the level of 15.8%. The highest sensory evaluation with very good dine value achieved varieties Evelin (78.0 points) and Spinela (77.8 points). As the best varieties for storage can be used varieties Rumelia, Arwen and Megan. For heat treatment are most suitable varieties Evelin and Spinela.

Status and Response of Sulphur in Alluvial Soils for Higher Yield of Potato

The current study was carried out to assess the status of forms of sulphur (S) in soils of Etawah district, Uttar Pradesh. Separate set of field experiment was carried out during rabi season of 2007–08 and 2008–09 at Etawah to study the effect of sources and levels of S on potato. The total S content in soils of Etawah district ranged from 75 to 190 mg kg−1 with a mean value of 130.9 mg kg−1. The mean values of organic-S, SO4-S and non-sulphate-S were 43.8, 12.1 and 74.2 mg kg−1, respectively. All the forms of S gave significantly positive correlation with organic carbon (OC) indicating S as the integral part of soil organic matter (SOM). Approximately 62% soils under study were deficient in available S. The results of field experiment revealed that the potato (Solanum tuberosum L.) crop responded significantly to applied S through various sources. Tuber yield of potato and starch content in tubers increased significantly with increasing levels of S up to 40 kg ha−1. Sulphur uptake also followed the similar trend of tuber yield. Among the sources of S tested, ammonium sulphate was best with respect to yield, starch content and uptake of S by potato tubers. Next in order were gypsum, elemental S and pyrite. The net return (Rs.135340 ha−1) and B/C ratio (1.91: 1) were higher when ammonium sulphate was used as a source of S. Potato crop grown with 60 kg S ha−1 gave maximum net return (Rs.147305 ha−1) and B/C ratio (2.08: 1). Ammonium sulphate recorded significantly higher S use efficiency and S uptake efficiency over other sources of S. Sulphur use efficiency and S uptake efficiency decreased with 60 kg S ha−1 over lower levels of S application.

Efekti stosowania nawozow kompleksowych w uprawie ziemniaka na wczesny zbior na glebie piaszczysto-gliniastej

To obtain a high tuber yield of early crop potato good conditions for plant growth must be ensured. Potato has a relatively shallow root system and requires significant nutrient inputs to maintain tuber productivity and quality. The paper presents the results of the research on the effect of complex fertilizers type NPK MgS with and without microelements from the nitrophoska (HydroComplex, Nitrophoska Blue Special and Viking 13) and the amophoska group (Polimag S), and single-nutrient fertilizers on the plant growth and tuber yield of very early potato cultivars (‘Aster’, ‘Fresco’, ‘Gloria’) on loamy sand soil. The field experiment was carried out in mideastern Poland (52°03'N, 22°33'E). Potatoes were harvested 75 days after planting (the end of June). The type of fertilizer (single-nutrient or complex fertilizer) slightly affected the growth of potato plants. With the use of complex fertilizers, the assimilation leaf area and leaf area index (LAI) were similar to the application of single-nutrient fertilizers. Of the examined complex fertilizers, Viking 13 (representing the nitrophoska group without microelements) resulted in a smaller increase of assimilation leaf area in comparison with the cultivation without mineral fertilization. The type of fertilizer exerted a greater influence on the plant growth of ‘Aster’ (Poland) than ‘Fresco’ (The Netherlands) and ‘Gloria’ (Germany). The productive effects of complex fertilizers in early crop potato culture on loamy sand soil were comparable with single-nutrient fertilizers. The highest tuber yield was achieved with the application of Nitrophoska Blue Special (from the nitrophoska group with the lowest NNH4+ concentration); the total tuber yield was higher on average by 2.94 t*ha-1 (21.0%) and the yield of marketable tuber fraction (diameter above 30 mm) by 2.55 t*ha-1 (20.4%) in comparison with the cultivation without mineral fertilization. Although the total tuber yield was a little lower, the share of large tubers (diameter above 51 mm) in the yield was recorded with the use of Polimag S (from the amophoska group and with the most Mg, S, Zn and B concentration of all complex fertilizers applied) and Viking 13 (from the nitrophoska group with Ca). The single-nutrient and complex fertilizers applied in the experiment had no effect on the dry matter, starch or Lascorbic acid content in potato tubers. Regardless of the type of fertilizer applied, the tuber yield, average weight of one tuber and the share of medium-sized tubers (diameter of 4150 mm) in the yield of ‘Aster’ were highest. The yield of marketable tuber fraction of the ‘Aster’ was higher than ‘Fresco’ and ‘Gloria’ on average by 3.03 t*ha-1 (22.0%) and 4.57 t*ha-1 (37.4%), respectively. About 25% of the ‘Gloria’ yield made up of non-marketable tubers (diameter below 30 mm). Tubers of ‘Aster’ contained more dry matter and starch than ‘Fresco’ and ‘Gloria’, however, the content of Lascorbic acid in tubers of the tested potato cultivars was similar.

SNPs in genes functional in starch-sugar interconversion associate with natural variation of tuber starch and sugar content of potato (Solanum tuberosum L.).

Starch accumulation and breakdown are vital processes in plant storage organs such as seeds, roots, and tubers. In tubers of potato (Solanum tuberosum L.) a small fraction of starch is converted into the reducing sugars glucose and fructose. Reducing sugars accumulate in response to cold temperatures. Even small quantities of reducing sugars affect negatively the quality of processed products such as chips and French fries. Tuber starch and sugar content are inversely correlated complex traits that are controlled by multiple genetic and environmental factors. Based on in silico annotation of the potato genome sequence, 123 loci are involved in starch-sugar interconversion, approximately half of which have been previously cloned and characterized. By means of candidate gene association mapping, we identified single-nucleotide polymorphisms (SNPs) in eight genes known to have key functions in starch-sugar interconversion, which were diagnostic for increased tuber starch and/or decreased sugar content and vice versa. Most positive or negative effects of SNPs on tuber-reducing sugar content were reproducible in two different collections of potato cultivars. The diagnostic SNP markers are useful for breeding applications. An allele of the plastidic starch phosphorylase PHO1a associated with increased tuber starch content was cloned as full-length cDNA and characterized. The PHO1a-HA allele has several amino acid changes, one of which is unique among all known starch/glycogen phosphorylases. This mutation might cause reduced enzyme activity due to impaired formation of the active dimers, thereby limiting starch breakdown.

Heterologous expression of AtPAP2 in transgenic potato influences carbon metabolism and tuber development

Changes in carbon flow and sink/source activities can affect floral, architectural, and reproductive traits of plants. In potato, overexpression (OE) of the purple acid phosphatase 2 of Arabidopsis (AtPAP2) resulted in earlier flowering, faster growth rate, increased tubers and tuber starch content, and higher photosynthesis rate. There was a significant change in sucrose, glucose and fructose levels in leaves, phloem and sink biomass of the OE lines, consistent with an increased expression of sucrose transporter 1 (StSUT1). Furthermore, the expression levels and enzyme activity of sucrose-phosphate synthase (SPS) were also significantly increased in the OE lines. These findings strongly suggest that higher carbon supply from the source and improved sink strength can improve potato tuber yield.

Effect of Hhydrogen Peroxide Foliar Spraying on Tuber's Quality of Three Potato Cultivars

Two field experiments concerning potato (Solanum tuberosum L.) crop werecarried out during two successive winter seasons of 2009/2010 and 2010/2011 in a private farm ata newly reclaimed area, in El-Amria region, Alexandria governorate, Egypt. The experiment wasperformed to study the effect of hydrogen peroxide (H2O2) on the potato processing quality and theeconomical characters. The split-plot design in three replicates was used, where potato cultivarswere placed in the main plots, while doses of foliar spraying with hydrogen peroxide were occupiedthe sub-plots. Three potato cultivars were tested in this investigation; Lady Rossetta, Valor andMondial. Four doses of hydrogen peroxide were used as zero, 25, 50 and 75 mM in the first year.Two higher doses, 100 and 125 mM of hydrogen peroxide were added in the second year. Potatoplant stem diameter was positively affected with the increasing of H2O2 concentrations from zero up to 125 mM. The results showed that the 25, 50 and 75 mM of H2O2 concentrations did not affect thepotato tuber yield. The other two high levels (100 and 125 mM) of H2O2 resulted in lower potatoyields. The number of tubers/ 10 Kg weight trait seemed to be affected with H2O2 concentrations, inwhich it was above the accepted number during the second year (more than 112 tubers/10 Kgweight).In the first year, the data indicated that spraying potato plants with 75 or 50 mM of H2O2significantly increased dry matter percentage compared with the control treatment. Both treatmentsof 75 and 50 mM of H2O2, produced the highest levels of tuber starch content in the first year , whilethe treatment 75 mM of H2O2, produced the highly tuber starch content with significant differencesamong the other tested treatment in the second year of the study. The effect of hydrogen peroxideon parenchyma cell diameter trait differed from year to another. The treatment of 50 mM of H2O2possessed the highest value for parenchyma cell diameter trait, whereas, the treatments of both 25and 125 mM of H2O2 increased the parenchyma cell diameter trait. The lowest chipping defectswere produced when potato plants sprayed with 50 mM H2O2. The control treatment gave thelowest mean value (result) where this treatment produced highly significant level of tuber chippingdefects.

The effect of gibberellic acid (GA3) on seed size and sprouting of potato tubers (Solanum tuberosum L.).

An experiment was performed to evaluate the effect of gibberellic acid (GA3) on seed size and sprouting of potato (Solanum tuberosum L.). The experiment was laid done in factorial design (3 × 3) using Agria, Marfona and Draga cultivars and three concentrations of GA3 (0, 5 and 10 mg/lit). Results showed that application of gibberellic acid at low concentrations (5 and 10 mg/lit) was able to increase general performance and productivity of seed tubers of potatoes. Seed tuber production was increased by application of using gibberellic acid in all cultivars. Total weight of seed tubers produced by application of 5 mg/lit GA3 was statistically different compared to control (p ≤ 0.05). Also, results showed that after one week from application of GA3, starch content decreased and total content of sugar increased in potato tuber. The tubers treated with GA3sprouted earlier while in control sprouting was very late and slow. Furthermore, we indicated that sugar content is one of the important parameters determining the sprouting of seed potatoes. Thus the sequence of events can be summarized as: Application of GA3 → Starch hydrolysis → Decrease of starch content of tubers → Production and increase of total sugar content → Dormancy breaking → Tuber sprouting. Key words: Potato (Solanum tuberosum L.), gibberellic acid (GA3), tuber size, tuber sprouting.

PREFERENSI PANELIS PADA TIGA KLON KENTANG TERHADAP KULTIVAR GRANOLA DAN ATLANTIK

The research objective was to determine the preferences panel of three clones of potato seed tubers G1 namely A5, PAS3063, PAS3064 and Granola and Atlantic cultivars as comparison varieties, as well as to determine levels of starch, sugar and water content. Based on the results of Kruskal Wallis test for flavor and texture parameters on the tuberswere not significantly different cooking shows, while the aroma and color were significantly different between clones / cultivars. Panelists on the test results for the parameters of boiled tubers taste, texture, aroma and color looks significantly different between clones / cultivars. Analysis of variance was significantly different levels of tuber starch content, sugar contentand moisture content. Gerombol analysis based on the preferences panel of taste, texture, aroma and color in fried and boiled potatoes indicate that the resemblance is closer to A5 Granola with similarity percentage of more than 54.76% and Atlantic closer resemblance to the PAS3063 and PAS3064 with similarity percentage of more than 77.38% .

Starch and flour extraction and nutrient composition of tuber in seven cassava accessions

Cassava (Manihot esculenta Crantz) roots (tubers) are used as staple food. Starch extracted from tubers is widely utilized as raw materials in industries. Dry matter (DM) content, starch and flour extraction and proximate composition were investigated in seven cassava accessions (Coc-A1, Kh-A2, Cow-A3, Sa-A4, Me-A5, Va-A6 and Sy-A8.) in 2010- 2011. Leaf DM varied from 20.51% in Me-A5 to 29.01% in Sy-A8; that of stem from 27.24% in Va-A6 to 32.10% (average of Sy-A8, Me-A5 and Sa-A4); and that of tuber from 37.30% in Kh-A2 to 45.26% in Sy-A8. Starch was extracted by blending chopped tuber followed by decantation. Tubers were sliced, sun dried and milled into flour. Tuber starch content (fresh wt. basis) varied between 15.04% in Sy-A8 and 24.97% (average of Coc-A1 and Me-A5); that of peel from 4.54% in Va-A6 to 5.85% in Coc-A1. Crude protein varied from 1.80% (average of Kh-A2, Cow-A3 and Sy-A8) to 4.53% in Va-A6. Crude fiber content varied from 1.95% (average of Sa-A4 and Coc-A1) to 4.27% in Cow-A3. Cyanogens present in cassava plant escape as hydrogen cyanide (HCN) during harvesting and processing. Variation for HCN existed and it was 140.95 mg/kg fresh tuber (average of Sy-A8 and Coc-A1) to 546.0 mg/kg fresh tuber in Va-A6. There was no detectable HCN in the extracted flour and starch. It may be concluded that genetic variation for DM, starch, protein and HCN existed in seven cassava accessions, and Coc-A1 may be a better one due to its lower HCN, higher DM and starch content. DOI: http://dx.doi.org/10.3329/jbau.v10i2.14698 J. Bangladesh Agril. Univ. 10(2): 217-222, 2012

Validation of candidate gene markers for marker-assisted selection of potato cultivars with improved tuber quality

Tuber yield, starch content, starch yield and chip color are complex traits that are important for industrial uses and food processing of potato. Chip color depends on the quantity of reducing sugars glucose and fructose in the tubers, which are generated by starch degradation. Reducing sugars accumulate when tubers are stored at low temperatures. Early and efficient selection of cultivars with superior yield, starch yield and chip color is hampered by the fact that reliable phenotypic selection requires multiple year and location trials. Application of DNA-based markers early in the breeding cycle, which are diagnostic for superior alleles of genes that control natural variation of tuber quality, will reduce the number of clones to be evaluated in field trials. Association mapping using genes functional in carbohydrate metabolism as markers has discovered alleles of invertases and starch phosphorylases that are associated with tuber quality traits. Here, we report on new DNA variants at loci encoding ADP-glucose pyrophosphorylase and the invertase Pain-1, which are associated with positive or negative effect with chip color, tuber starch content and starch yield. Marker-assisted selection (MAS) and marker validation were performed in tetraploid breeding populations, using various combinations of 11 allele-specific markers associated with tuber quality traits. To facilitate MAS, user-friendly PCR assays were developed for specific candidate gene alleles. In a multi-parental population of advanced breeding clones, genotypes were selected for having different combinations of five positive and the corresponding negative marker alleles. Genotypes combining five positive marker alleles performed on average better than genotypes with four negative alleles and one positive allele. When tested individually, seven of eight markers showed an effect on at least one quality trait. The direction of effect was as expected. Combinations of two to three marker alleles were identified that significantly improved average chip quality after cold storage and tuber starch content. In F1 progeny of a single-cross combination, MAS with six markers did not give the expected result. Reasons and implications for MAS in potato are discussed.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-012-2035-z) contains supplementary material, which is available to authorized users.

Novel candidate genes influencing natural variation in potato tuber cold sweetening identified by comparative proteomics and association mapping

BackgroundHigher plants evolved various strategies to adapt to chilling conditions. Among other transcriptional and metabolic responses to cold temperatures plants accumulate a range of solutes including sugars. The accumulation of the reducing sugars glucose and fructose in mature potato tubers during exposure to cold temperatures is referred to as cold induced sweetening (CIS). The molecular basis of CIS in potato tubers is of interest not only in basic research on plant adaptation to environmental stress but also in applied research, since high amounts of reducing sugars affect negatively the quality of processed food products such as potato chips. CIS-tolerance varies considerably among potato cultivars. Our objective was to identify by an unbiased approach genes and cellular processes influencing natural variation of tuber sugar content before and during cold storage in potato cultivars used in breeding programs. We compared by two-dimensional polyacrylamide gel electrophoresis the tuber proteomes of cultivars highly diverse for CIS. DNA polymorphisms in genomic sequences encoding differentially expressed proteins were tested for association with tuber starch content, starch yield and processing quality.ResultsPronounced natural variation of CIS was detected in tubers of a population of 40 tetraploid potato cultivars. Significant differences in protein expression were detected between CIS-tolerant and CIS-sensitive cultivars before the onset as well as during cold storage. Identifiable differential proteins corresponded to protease inhibitors, patatins, heat shock proteins, lipoxygenase, phospholipase A1 and leucine aminopeptidase (Lap). Association mapping based on single nucleotide polymorphisms supported a role of Lap in the natural variation of the quantitative traits tuber starch and sugar content.ConclusionsThe combination of comparative proteomics and association genetics led to the discovery of novel candidate genes for influencing the natural variation of quantitative traits in potato tubers. One such gene was a leucine aminopeptidase not considered so far to play a role in starch sugar interconversion. Novel SNP’s diagnostic for increased tuber starch content, starch yield and chip quality were identified, which are useful for selecting improved potato processing cultivars.

Normal Operating Range of Bacterial Communities in Soil Used for Potato Cropping

In this study, the impacts of six potato (Solanum tuberosum) cultivars with different tuber starch allocations (including one genetically modified [GM] line) on the bacterial communities in field soil were investigated across two growth seasons interspersed with 1 year of barley cultivation, using quantitative PCR, clone library, and PCR-denaturing gradient gel electrophoresis (DGGE) analyses. It was hypothesized that the modifications in the tuber starch contents of these plants, yielding changed root growth rates and exudation patterns, might have elicited altered bacterial communities in the soil. The data showed that bacterial abundances in the bulk soil varied over about 2 orders of magnitude across the 3 years. As expected, across all cultivars, positive potato rhizosphere effects on bacterial abundances were noted in the two potato years. The bulk soil bacterial community structures revealed progressive shifts across time, and moving-window analysis revealed a 60% change over the total experiment. Consistent with previous findings, the community structures in the potato rhizosphere compartments were mainly affected by the growth stage of the plants and, to a lesser extent, by plant cultivar type. The data from the soil under the non-GM potato lines were then taken to define the normal operating range (NOR) of the microbiota under potatoes. Interestingly, the bacterial communities under the GM potato line remained within this NOR. In regard to the bacterial community compositions, particular bacterial species in the soil appeared to be specific to (i) the plant species under investigation (barley versus potato) or, with respect to potatoes, (ii) the plant growth stage. Members of the genera Arthrobacter, Streptomyces, Rhodanobacter, and Dokdonella were consistently found only at the flowering potato plants in both seasons, whereas Rhodoplanes and Sporosarcina were observed only in the soil planted to barley.

Study on Correlation between the Starch Content of Potato Tuber and its Viscoelastic Characteristics

When potato tubers had received the exogenic action, water and starch in tubers generated tougor pressure which would act on cell walls in the tuber tissue, so starch content and water ratio have an obvious effect on the mechanical characteristics of potato tubers. In order to provide a mechanical method for detecting the starch content of potato tubers, correlation between viscoelastic characteristics and starch content of tubers was studied. In the research, the tubers of Desiree potato were compressed by cylindrical probe, and showed nonlinear stress-strain curves. The viscoelastic model of potato tuber was established, and its viscoelastic parameters were determined. Meanwhlie, the starch content and water ratio of potato tuber were detected after mechanical tests, and the correlation between viscoelastic parameters and starch content was analysed. According to the results of correlation analysis, viscosity coefficient which had been obtained from the viscoelastic model was significantly correlated with starch content and water ratio. Finally, the regression equation of starch content and the viscosity coefficient was determined.

Effect of nitrogen application on selected nutritional components of potato tubers

In this work the influence of graduated nitrogene fertilizers doses to the soil on starch and vitamin C formation in potato tubers grown in field conditions in locality Veľká Čalomija was studied. The investigated potato cultivar Solara is medium early potato cultivar. The determined average starch content in potato samples ranged in interval 12,426 % - 15,084 %, while the highest starch content was determined in variant 1 (without nitrogen addition to the soil). The starch content in potato tubers was decreased in order: variant 1 (15,084 %) > variant 2 (14,427 %) > variant 3 (14,378 %) > variant 4 (14,023 %) > variant 5 (12,603 %) > variant 6 (12,426 %). The content of C vitamin was increased with the graduated nitrogen doses to the soil only till variant 4 and after that the content of vitamin C was decreased. The average content of C vitamin ranged in interval 3,786 - 6,225 mg.kg-1 of fresh matter.

Tapping natural variation at functional level reveals allele specific molecular characteristics of potato invertase Pain‐1

Biochemical, molecular and genetic studies emphasize the role of the potato vacuolar invertase Pain-1 in the accumulation of reducing sugars in potato tubers upon cold storage, and thereby its influence on the quality of potato chips and French fries. Previous studies showed that natural Pain-1 cDNA alleles were associated with better chip quality and higher tuber starch content. In this study, we focused on the functional characterization of these alleles. A genotype-dependent transient increase of total Pain-1 transcript levels in cold-stored tubers of six different genotypes as well as allele-specific expression patterns were detected. 3D modelling revealed putative structural differences between allelic Pain-1 proteins at the molecule's surface and at the substrate binding site. Furthermore, the yeast SUC2 mutant was complemented with Pain-1 cDNA alleles and enzymatic parameters of the heterologous expressed proteins were measured at 30 and 4 °C. Significant differences between the alleles were detected. The observed functional differences between Pain-1 alleles did not permit final conclusions on the mechanism of their association with tuber quality traits. Our results show that natural allelic variation at the functional level is present in potato, and that the heterozygous genetic background influences the manifestation of this variation.

Soil nitrogen variability in relation to seasonal nitrogen cycling and accumulation of nitrogenous components in starch processing potatoes

Seasonal dynamics of total soil nitrogen, ammonium and nitrate ions contents were evaluated for a processing potato field experiment conducted on three sites with different altitudes. Fertilization levels of 100 and 200 kg N ha−1 applied before potato crop planting were compared. Content of soil ammonium and nitrate ions ranged from 1.5 to 149 mg kg−1 and from 3.0 to 108 mg kg−1 on soil dry matter basis, respectively and showed strong seasonal dynamics with a rapid increase of the content during June and subsequent fall down to initial values. The nitrogen fertilization level had minimal effect on seasonal dynamic of total soil nitrogen, ammonium and nitrate ions contents. The higher fertilization level significantly increased crude protein content in potato tubers and yield of crude protein per area unit. The factors of starch content in potato tubers and yield per area unit were affected negatively by the higher dose of nitrogen fertilization. It could be concluded that the dose of 100 kg N ha−1 is sufficient for production of potato tubers with high content of both crude protein and starch, especially in production areas with higher altitude. The dose of 200 N is justifiable only in production areas with lower altitude (below 400 m a.s.l.) that are not so suitable for accumulation of crude protein and starch in potato tubers.

Study of structural and rheological properties of starch isolated from genetically modified potato

It has been found in this work that the starchiness and starch content in tubers of GM potato and tubers of initial Lugovskoi potato variety are identical. No differences and difficulties were observed upon starch preparation from GM and common potato. Starch samples isolated from GM potato conform to the current standard for potato starch. The starch isolated from GM potato has a higher melting point, i.e., it is more thermally stable as compared with the starch isolated from a control sample. The bulk modulus of gels obtained from starch isolated from GM potato is higher in comparison with that of gels prepared from starch isolated from the control sample. Thermodynamic and rheological properties of starch from GM potato provide a possibility to predict its application in the manufacture of thermostable and strong polymeric materials.

Effect of Composted Organic and Mineral Fertilizers Mixture on Some Important Characters of Potato Plants Grown in Desert Land

Two field experiments were conducted at the Research Farm of the Environmental Studies and ResearchInstitute, Menoufiya University, Sadat City, Egypt; during the two winter seasons of 2006/2007 and 2007/2008. The objective of this investigation was to study the effects of two methods of composite of organic and mineral fertilizers mixture through , two systems of fertilizing, i.e., external compost with mineral fertilizers, external compost with bio-fertilizer; internal compost with mineral fertilizers; and internal compost with bio-fertilizer as well as the control; on some characters of potato tubers ofDiamont local cultivar. The obtained results indicated generally that the most important findings were as follows:- Plant height had the significantly highest value for the external compost with mineral fertilizer.-The four treatments under study did not vary significantly regarding plant fresh weight being significantly higher than the control.-Treatments of the external compost with mineral and biofertilizer and internal compost with bio-fertilizer gave highly significantly increment in tuber weight as compared to the control.-The significantly highest total yield (ton/fed) was achieved by treatment of external compost with mineral and bio-fertilizer.-Treatments of the external compost with bio-fertilizer and internal compost with bio-fertilizer gave significantly the highest tuber dry matter (%).- Starch and sugar content of tubers exhibited significantly different values due to the treatment applied and the season of growth.In conclusion, despite the superiority of the four treatments to the control, the treatment of externalcompost with mineral fertilizers was the best in terms of improvement the vegetative and yield properties. This treatment was followed by the treatment of external compost with bio-fertilizer.

Enhancing the expression of starch synthase class IV results in increased levels of both transitory and long‐term storage starch

Starch is an important renewable raw material with an increasing number of applications. Several attempts have been made to obtain plants that produce modified versions of starch or higher starch yield. Most of the approaches designed to increase the levels of starch have focused on the increment of the amount of ADP-glucose or ATP available for starch biosynthesis. In this work, we show that the overexpression of starch synthase class IV (SSIV) increases the levels of starch accumulated in the leaves of Arabidopsis by 30%-40%. In addition, SSIV-overexpressing lines display a higher rate of growth. The increase in starch content as a consequence of enhanced SSIV expression is also observed in long-term storage starch organs such as potato tubers. Overexpression of SSIV in potato leads to increased tuber starch content on a dry weight basis and to increased yield of starch production in terms of tons of starch/hectare. These results identify SSIV as one of the regulatory steps involved in the control of the amount of starch accumulated in plastids.