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Abstract Acacia mearnsii and Ilex paraguariensis are tree species of great social and economic importance in Brazil, demanding clonal cultivars. Their shoots possess a reservoir of totipotent cells with suitable potential for adventitious rooting, essential for mass production of high-quality seedlings. This study aimed to gain new insights into how anatomical barriers, i.e. sclerified tissues in the cortical region, may affect the adventitious rooting of cuttings from these species through histological examinations. For both species, histological analysis revealed significant diagnostic features. Tissue decay appears to be equivalent to an anatomical barrier in A. mearnsii. Starch abundance was notable in clones with higher rooting competence of I. paraguariensis, but they were not observed in the fundamental tissues of A. mearnsii, regardless of the rooting competence of the clone. The main differences in adventitious rooting were associated with the speed of response, initiated from cortical meristems, followed by differentiation of conductive tissue from newly formed tissue, connecting the periphery with the secondary vascular tissue. Thus, this newly formed tissue with parenchymatic structure provides the necessary structural basis for radial vascular connections. For both studied species, rhizogenesis presents distinct barriers to rooting, nevertheless these are not necessarily of anatomical nature.

The aim was to evaluate if the inclusion of exogenous amylolytic enzyme affect the nutrient intake and digestibility in ewes fed high-concentrate diets containing flint corn. Five Santa Inês × Dorper crossbred ewes (54.04 ± 4.5 kg and aged 8 months) were used in a 5 x 5 Latin square design. All animals were housed in individual metabolic cages for 60 days. The treatments consisted of a control diet (without amylolytic enzyme) and four inclusion levels of an amylolytic enzyme (3,000, 6,000, 9,000, and 12,000 α-amylase dextrinizing units [DU] kg-1 dry matter [DM]). The enzyme was mixed into the feed at the time of supply to the animals. Data were analyzed by ANOVA, and orthogonal polynomial contrasts were used. Nutrient intake was not influenced by amylolytic enzyme inclusion. The digestibility of DM, organic matter, neutral detergent fiber, total carbohydrates, non-fibrous carbohydrates, and gross energy showed a quadratic increase with enzyme inclusion (P

Turning the food waste into a fuel source such as charcoal briquette was one of the alternatives in managing the food wastes disposal. In this present work, food waste was converted into charcoal by microwave irradiation technique. Application of binders such as potato starch and carboxymethyl cellulose (CMC) at ratios of 5%,10% and 15% for briquetting purpose were investigated in terms of its chemical and physical characteristics. Result showed that the briquette formed using the starch as the binder performed better in combustion quality than that of carboxymethylcellulose (CMC). A good quality of charcoal briquette has capability to withstand impact during packaging, handling, and transportation. Standard physical characteristic that was tested for briquette includes moisture content, compressive strength, and impact resistance. Calorific value of briquette was studied to analyse energy content in the briquette. The study showed that food waste charcoal has calorific value comparable to that of the commercial charcoal. However, the addition of binders showed some reduction in the energy content, with more reduction when CMC is added. In terms of combustion characteristic, the addition of binders does not alter the combustion profile in comparison to the raw food waste charcoal’s profile. The ignition and burnout temperatures of the food waste charcoal briquette showed a better performance with and without binders as compared to the commercial charcoal. In terms of physical characteristics, CMC has showed as an excellent binder with highest shatter index value. Overall, in terms of chemical properties, addition of 10% starch showed a better performance, while addition of 10% CMC showed a better performance in terms of physical characteristics. This finding is beneficial for briquette industry in the development of green product using biomass, but further research is essential before production of briquette take place.

Experiments were conducted to study the rheological behavior of iota-carrageenan Gels to which potato starch and low-esterified amidated pectin were added. The rheological measurements of carrageenan jellies were performed by a texture analyzer at different concentrations of gelling agent (iota-carrageenan) and fixed concentrations of starch (1.3 %) and pectin (0.3%). Following the experiments, rheological patterns related to rupture force, rupture deformation and firmness of the gels were evaluated. Potato starch and low esterified amidated pectin at certain concentrations do not show synergistic effects with iota-carrageenan. The addition of low esterified amidated pectin or potato starch in iota-carrageenan gel results in a significant reduction in deformation and a minimal reduction in the rupture force.

Carbohydrate reserves in grapevine are stored in form of starch and soluble sugars. The present study was conducted in order to understand the dynamics of insoluble carbohydrate reserves during dormancy season of some table and wines grapevine varieties. Six year old grapevine varieties (Muscat de Hamburg, Napoca, Cardinal, Perla de Csaba, Fetească regală, Muscat Ottonel, Pinot noir and Fetească neagră) were sampled before winter. During dormancy, starch level in canes was appreciated by iodin in potassium iodide method, wood and pith diameter measured and bud viability tested. The levels of starch in grape canes at the beginning of dormancy (November) was highest in Muscat de Hamburg (3.89), Napoca and Fetească regală (3.76) and the lowest in Cardinal (3.47). Due to climatic conditions over dormancy, starch began to resynthesize already during January and February, with significantly high levels for all varieties. Wood/pith ratio was highly correlated with starch level. Bud viability was directly influenced by the starch level in canes.

Salicylic acid (SA) is a key component of plant defence, which exerts a concentration-dependent effect on photosynthesis under multi-faceted influence of light. Photosynthetic activities and chloroplast morphology were studied in tomato plants after treatment with a sublethal, 0.1 mM, and a cell death-inducing, 1 mM concentrations of SA under normal photoperiod during light phase and after a prolonged dark phase. SA (1 mM) decreased the maximal (Fv/Fm) and effective quantum yields of PSII [Y(II)] and PSI [Y(I)] under both environmental conditions, however, the photoprotective processes were not significantly different between light and dark samples. Decrease in grana height, thylakoid dilation and deformation of lumen were also observed in the light. In contrast to illuminated samples, 0.1 mM SA decreased Y(II) and Y(I) after dark incubation, but nonphotochemical energy dissipation and cyclic electron flow increased, suggesting that the photoprotective mechanisms could be activated in plants exposed to prolonged darkness.

In this research, the rheological behavior and stability of suspensions containing Si3N4, Al2O3, Y2O3 and starch were investigated in order to use them in the starch consolidation casting of porous silicon nitride. Dolapix CE64 was used as the dispersant. Then, the effect of some parameters such as Si3N4 surface oxidation, dispersant content, solid loading and starch content on the viscosity and rheological behavior of Si3N4-starch slurry was determined. Surface oxidation of Si3N4 powder at 800°C for 2 hours reduced the viscosity of the slurry, effectively. The best dispersant content was 0.4 wt. %, relative to ceramic powders. Slurries containing 30 to 40 vol. % and 7.5 to 25 vol. % starch, relative to total solid loading, had the suitable viscosity and the sufficient stability for casting by the starch consolidation method.

The objective of this study was to evaluate the replacement of 0, 25, 50, 75 and 100% of ground corn (GC) with pelleted soybean hulls (SH) in the concentrate portion of cattle diets. The evaluation was conducted using five 13-month-old Nellore steers cannulated in the rumen, with a mean body weight of 265.00 + 11.60 kg. The steers received a diet composed of 90% concentrate and 10% sugarcane bagasse as the only source of roughage. The statistical design used was a 5x5 Latin square. There was no effect (p > 0.05) of replacement levels or interaction (p > 0.05) between replacement levels and sampling time on ruminal pH, which ranged from 5.8 to 6.0. The apparent digestibility of DM, CP, EE, CHOT and CHONF were not influenced (p > 0.05) by the replacement levels, showing mean values of 67.88 + 2.02; 67.43 + 2.89; 68.29 + 4.11; 70.54 + 1.68 and 80.21 + 1.85%, respectively. The NDF digestibility increased linearly (p < 0.05) with the replacement of corn with soybean hulls. There was no effect (p > 0.05) of replacement levels on time spent feeding (F) and total idle time (TI), with mean values of 10.51 and 4.61% of the day, respectively. However there was a quadratic effect (p < 0.05) of soybean hull inclusion on the time spent ruminating. It was concluded that although the replacement of corn with soybean hull does not improve the ruminal pH of steers fed diets with a high proportion of concentrate, pelleted soybean hulls improve the digestibility of the fibrous fraction of the diet and increase the time spent ruminating, indicating that this ingredient can be included in high-concentrate diets to improve economic efficiency.

Corn silage digestibility studies have focussed on genetically distant corn types. Conversely, silage additive studies monitored fermentation differences without discussing the subject of hybrid digestibility. How ensiling phases and additives affect silage quality in commercial corn hybrids has not been properly examined yet. As corn silage quality is a result of combined silage fermentation and digestibility characteristics, the aim of the study was to examine fermentation and digestibility responses to inoculant application in whole-plant corn silage of commercial hybrids intended for silage production in several time points during ensiling. Three corn hybrids grown under identical conditions in a split-plot field test were ensiled without inoculant application and with inoculant containing lactic acid bacteria and carbohydrate-degrading enzymes. Silages were sampled before ensiling, at the peak of the fermentation phase and during the stable phase. The fermentation profile, carbohydrate fraction, ruminal in vitro true dry matter digestibility, ruminal in vitro starch digestibility, and ruminal in vitro neutral detergent fibre digestibility were monitored. Although adding inoculant to silage improved its lactic acid production and decrease in pH, it did not affect its starch and fibre contents or their digestibility. Digestibility improved as ensiling continued, with the highest in vitro neutral detergent fibre digestibility and in vitro true dry matter digestibility values observed in the stable phase. Corn hybrids in this study differed in main fermentation characteristics, carbohydrate contents, and digestibility. These results suggest that even for commercial corn hybrids, the hybrid type is more important than inoculant for optimising silage characteristics and digestibility. Corn silage quality is a result of silage fermentation and digestibility characteristics. Studies so far were focussed on the influence of either inoculant on fermentation characteristics, or genetically distant corn types on chemical composition and digestibility of main components. This research combines both approaches; it is a fermentation and digestibility study of diverse commercial hybrids ensiled with inoculant during storage. The study shows that even for commercial corn hybrids, when addressing silage fermentation characteristics and digestibility, a hybrid type is more relevant than inoculant. [ABSTRACT FROM AUTHOR]

After an extended delay, the level of acceptance of exogenous phytases by the global chicken-meat industry is now almost complete. Contemporary bacterial phytases degrade phytate primarily in the gizzard. The extent of phytate degradation determines the extent to which phytate-bound phosphorus (P) is liberated; however, studies designed to investigate phytate degradation along the digestive tract have generated some confusing outcomes. This may be related to the reactivity of the phytate moiety, coupled with problems with inert dietary markers and perhaps a lack of complete and uniform extractions of phytate from digesta due to variations in digesta pH and phytate solubility. Quite recently, phytase was shown to have profound impacts on sodium (Na) digestibility coefficients in four segments of the small intestine. This has obvious implications for intestinal uptakes of glucose and amino acids via their respective Na+-dependent transport systems and it is possible that phytate and phytase have reciprocal impacts on 'sodium pump' (Na+, K+-ATPase) activity. It has been recently demonstrated unequivocally that phytase has the capacity to increase amino acid digestibility coefficients to the extent that phytase may generate a 'proximal shift' in the sites of amino acid absorption. The impact of phytase on starch digestibility is more equivocal and phytase responses may stem more from enhanced glucose absorption rather than starch digestion. The acceptance of phytase is hardly surprising, given its capacity to increase P utilisation coupled with numerous other positive influences that are still being properly realised. [ABSTRACT FROM AUTHOR]

Vase life is one of the most important characteristics in the quality of cut flowers. The carbohydrate content of petals from each cultivar can be a decisive factor to vase life of gladiolus flowers. Despite exposure to ethylene does not affect the life of open florets of gladiolus flowers, it may reduce the flower’s commercial life due the occurrence of flower buds abortion. This study thus aimed to evaluate the flower opening and the vase life of gladiolus flowers according to ethylene sensitivity and carbohydrate content of each cultivar. The gladiolus cultivars used in Experiment I were ‘Amsterdam’, ‘Blue Frost’, ‘Gold Field’, ‘Green Star’, ‘Jester’, ‘Lavender’, ‘Red Beauty’, ‘Rose Supreme’, ‘Traderhorn’, and ‘Verônica’. Stems were stored in airtight chambers and exposed to the ethylene concentrations of 0, 0.1, 1.0, 10, 100, and 1000 μL L−1 for 24 h. Subsequently, flower stem were placed in a test tube with distilled water when were evaluated for percentage of flower opening and vase life. In Experiment II, three cultivars (‘Amsterdam’, ‘Red Beauty’, and ‘Verônica’) were chosen based on the lowest, medium, and highest vase life in Experiment I, respectively. Total soluble sugars, reducing sugars, and starch contents were evaluated in five flower developmental stages. No effect of ethylene on the flower opening or alterations in flower opening between cultivars. The vase life of gladiolus flowers differed between cultivars regardless of ethylene action. ‘Verônica’ and ‘Amsterdam’, which had the highest and lowest vase life, respectively, differed as to the total soluble sugar content. Ethylene does not influence the flower opening or vase life of the gladiolus cultivars studied. In these cultivars, the maintenance of flower opening is attributed to total soluble sugars content, which, in turn, is a major determinant of the vase life.

The present work had as objective to evaluate the effects of high grain diets on fecal parameters in 20 Nellore bovines at 28 months of age. The experimental design was completely randomized. Treatments were constituted of the following diets: total mixed ration + sugarcane bagasse DT + BIN (10% in natura sugarcane bagasse, 54.52% ground sorghum, 10.94% cottonseed, 18% soybean hull, 2.54% soybean meal, and 4% premix); whole corn grain MGI (75% whole corn grain, 10% soybean hull, and 15% premix) and total mixed ration DT (44.41% ground sorghum, 16.7% cottonseed, 28.89% soybean meal, and 10% premix). For the assessment of feces pH and fecal starch, samples of feces were taken from the rectum of each animal on the 54th, 55th, 56th and 57th days of the experiment in the morning. Fecal pH was determined after the addition of 100 mL of distilled water in 15 g of fresh feces by the introduction of the tip of the electrode of a microprocessed pH meter. The remaining sample was stored in ice for later freezing. Fresh feces of the animals were evaluated daily during the whole experimental length in three periods aiming at evaluating occurrences of gut disturbances. Percentage means of fecal starch, fecal dry matter, pH in the site of starch fermentation and starch intake were not influenced by treatments (P>0.05). NDF of feces and score of fecal consistency were influenced by treatments (P

The aim of this paper was to evaluate microbiological characteristics of meat products produced under federal inspection by industries in the State of Paraná (Brazil), following Brazilian regulations. According to the type of meat product, quantification of nitrite and starch was also determined. All samples were collected at the plant and all analysis were carried out according to the Brazilian Ministry of Agriculture, Livestock and Food Supply´s recommendations. From 131 samples analyzed, five (3.82%) were contaminated by Salmonella sp. and three (2.3%) presented fecal coliforms. The other samples were legally acceptable. Frankfurters showed starch levels ranging from 1.71 % to 10.28%. In bologna, this variation ranged from 3.01 % to 16.5%. Residual nitrite levels in all products ranged from 3.7 mg/kg to 293.10 mg/kg. An amount of 23 samples (1 8.4%) had residual nitrite levels higher than legal limits, with a medium level of 395.91 mg/kg. The results found suggest that, although the analyzed samples present good sanitary quality, some producers need to be more carefully inspected, in order to attend Brazilian regulations for meat products.

The objective of the present study was to evaluate and compare the in vitro cecal fermentation (by the gas production technique), in hairless Mexican pig and Asian pig, adding cellulose or starch as a substrates (0, 100, 200, 30 and 400 mg/ g DM). 12 pigs were slaughtered ( BW= 104±0.5 kg), six of each genotype, and after that take cecal content of each one, and it was made a pool using two pigs per genotype; after that per substrate (cellulose or starch) in each concentration, it were incubated in three flasks per pool with inoculums and it made three incubation series. The experimental design use the effect of genotype, substrate and concentration of the substrate added on the variables of in vitro fermentation. The averages of the data were compared by turkey’s method. In vitro gas production was higher (P

We investigated the tolerance to flooding in reducing conditions of five maize inbred lines and identified a quantitative trait locus (QTL) for the trait. Flooding treatment with 0.1% to 0.4% starch solution for 14 d reduced soil redox potential to about – 200 mV, mimicking reducing conditions in soil. Treatment with 0.2% starch revealed wide varietal differences in dry matter production among the five maize inbred lines. We identified the QTL for flooding tolerance in reducing conditions in a population of 178 F2 plants derived from a cross of inbred lines F1649 (tolerant) and H84 (sensitive). Flooding tolerance, evaluated as the degree of leaf injury following treatment with 0.2% starch solution, revealed wide variation in the F2 population. Amplified fragment length polymorphism (AFLP) markers linked to flooding tolerance gene(s) were screened with 64 AFLP primer combinations using 15 of the 178 F2 plants from each extreme representing the ‘tolerant’ and ‘sensitive’ plants, and found 11 AFLP markers associated with flooding tolerance. Of these, 10 co-segregated and were assigned to chromosome 1. Six SSR primer pairs around these markers were used to construct a linkage map. Composite interval mapping analysis revealed that a single QTL for degree of leaf injury was located on chromosome 1 (bin 1.03-4). Another QTL for flooding tolerance, evaluated as dry matter production under flooding with 0.2% starch, was located at the same position. These results suggest the potential to increase productivity by transferring flooding tolerance genes from F1649 to elite maize inbred lines.

Sweet corn remains at its optimum harvest maturity for a very short period, and quality changes rapidly following its peak. This study investigates the changes in carbohydrate concentration of three genotypes of sweet corn: sugary ( su-1 ), sugar enhanced ( se ) and supersweet or shrunken ( sh2 ) at three stages of maturity. The analysis of variance revealed differences between genotypes for carbohydrates (sugars and starch) and between stages of maturity (moisture content). Average sugar concentration of su-1 corn was 5% higher than that of se corn and 52% higher than that of sh2 corn. The average starch concentration of su-1 corn was 27% lower than that of se corn and 66% lower than that of sh2 corn. The average moisture content of su-1 corn was 3% lower than that of se corn and 1% lower than that of sh2 corn. [ABSTRACT FROM AUTHOR]

Amyloglucosidase from A. niger was covalently immobilized onto poly( GMA-co-EGDMA) by the glutaraldehyde and periodate method. The immobilization of amyloglucosidase after periodate oxidation gave a preparate with the highest specific activity reported so far on similar polymers. The obtained immobilized preparates show the same pH optimum, but a higher temperature optimum compared with the soluble enzyme. The kinetic parameters for the hydrolysis of soluble starch by free and both immobilized enzymes were determined. .

Microorganisms have the ability to secrete enzymes when they are grown in the presence of certain substrates. Amylases are among the most important industrial enzymes and are of great significance in biotechnological studies. Bacteria belonging to the genus Bacillus were isolated using mannitol egg yolk polymyxin B (MYP) agar a highly selective media for Bacillus cereus isolation. The isolates were tested for α-amylase production on nutrient agar supplemented with starch and in submerged fermentation. The bacteria isolated and identified (using the Microgen Bacillus identification kit) were all Bacillus cereus and SB2 had the largest zone of hydrolysis of 12mm on nutrient agar supplemented with starch as well as the highest enzyme activity of 1.62U/ml. Amylase activity of 2.56U/ml was obtained after 24 hours incubation in submerged fermentation. When amylase enzyme production parameters where optimized, maximum amylase activity was obtained at a pH of 6.5, temperature of 350C, incubation time of 24 hours and 4% inoculums concentration. Bacillus cereus SB2 is a potential isolate for alpha-amylase production with soluble starch as the sole carbon source in submerged fermentation.

Diurnal growth patterns in Arabidopsis depend on the photoperiod and pace carbon use with the diurnal regulation of starch turnover. Correlation analyses reveal that trehalose 6-phosphate and shikimate play an important role in coordination of growth with the carbon supply.In short photoperiods, plants accumulate starch more rapidly in the light and degrade it more slowly at night, ensuring that their starch reserves last until dawn. To investigate the accompanying changes in the timing of growth, Arabidopsis was grown in a range of photoperiods and analyzed for rosette biomass, photosynthesis, respiration, ribosome abundance, polysome loading, starch, and over 40 metabolites at dawn and dusk. The data set was used to model growth rates in the daytime and night, and to identify metabolites that correlate with growth. Modeled growth rates and polysome loading were high in the daytime and at night in long photoperiods, but decreased at night in short photoperiods. Ribosome abundance was similar in all photoperiods. It is discussed how the amount of starch accumulated in the light period, the length of the night, and maintenance costs interact to constrain growth at night in short photoperiods, and alter the strategy for optimizing ribosome use. Significant correlations were found in the daytime and the night between growth rates and the levels of the sugar-signal trehalose 6-phosphate and the amino acid biosynthesis intermediate shikimate, identifying these metabolites as hubs in a network that coordinates growth with diurnal changes in the carbon supply. [ABSTRACT FROM AUTHOR]

Metabolic analysis of various mutants impaired in nitrate assimilation pathways (NIA1, NIT2 loci) revealed the essential role of NIT2 and intracellular nitrate in the control of biomass yield and storage carbohydrate product biosynthesis, such as starch, oil, precursors of biofuelMicroalgae are receiving increasing attention as alternative production systems for renewable energy such as biofuel. The photosynthetic alga Chlamydomonas reinhardtii is widely recognized as the model system to study all aspects of algal physiology, including the molecular mechanisms underlying the accumulation of starch and triacylglycerol (TAG), which are the precursors of biofuel. All of these pathways not only require a carbon (C) supply but also are strongly dependent on a source of nitrogen (N) to sustain optimal growth rate and biomass production. In order to gain a better understanding of the regulation of C and N metabolisms and the accumulation of storage carbohydrates, the effect of different N sources (NH4NO3 and ) on primary metabolism using various mutants impaired in either NIA1, NIT2 or both loci was performed by metabolic analyses. The data demonstrated that, using NH4NO3, nia1 strain displayed the most striking phenotype, including an inhibition of growth, accumulation of intracellular nitrate, and strong starch and TAG accumulation. The measurements of the different C and N intermediate levels (amino, organic, and fatty acids), together with the determination of acetate and remaining in the medium, clearly excluded the hypothesis of a slower and acetate assimilation in this mutant in the presence of NH4NO3. The results provide evidence of the implication of intracellular nitrate and NIT2 in the control of C partitioning into different storage carbohydrates under mixotrophic conditions in Chlamydomonas. The underlying mechanisms and implications for strategies to increase biomass yield and storage product composition in oleaginous algae are discussed. [ABSTRACT FROM PUBLISHER]

To explain the low levels of starch, high levels of (1,3;1,4)-β-glucan, and thick cell walls in grains of Brachypodium distachyon L. relative to those in other Pooideae, aspects of grain development were compared between B. distachyon and barley (Hordeum vulgare L.). Cell proliferation, cell expansion, and endoreduplication were reduced in B. distachyon relative to barley and, consistent with these changes, transcriptional downregulation of the cell-cycle genes CDKB1 and cyclin A3 was observed. Similarly, reduced transcription of starch synthase I and starch-branching enzyme I was observed as well as reduced activity of starch synthase and ADP-glucose pyrophosphorylase, which are consistent with the lowered starch content in B. distachyon grains. No change was detected in transcription of the major gene involved in (1,3;1,4)-β-glucan synthesis, cellulose synthase-like F6. These results suggest that, while low starch content results from a reduced capacity for starch synthesis, the unusually thick cell walls in B. distachyon endosperm probably result from continuing (1,3;1,4)-β-glucan deposition in endosperm cells that fail to expand. This raises the possibility that endosperm expansion is linked to starch deposition. [ABSTRACT FROM AUTHOR]

Rheological modeling of cassava flours and starches during an extrusion process was made in order to predict the effect of shear rate, temperature and water contents on viscosity. Experimentation was made on a high pressure twin bore capillary rheometer (Rosand RH-7) and viscosity data were adjusted to the Harper rheological model. All materials presented a characteristic shear thinning behaviour, but starch viscosity was more sensitive to changes of the processing conditions such as temperature and water contents, whereas flour viscosity was influenced by fiber and protein which interfered with starch gelatinization.

Plants have duplicate versions of the oxidative pentose phosphate pathway (oxPPP) enzymes with a subset localized to the chloroplast. The chloroplast oxPPP provides NADPH and pentose sugars for multiple metabolic pathways. This study identified two loss-of-function alleles of the Zea mays (maize) chloroplast-localized oxPPP enzyme 6-phosphogluconate dehydrogenase (6PGDH). These mutations caused a rough endosperm seed phenotype with reduced embryo oil and endosperm starch. Genetic translocation experiments showed that pgd3 has separate, essential roles in both endosperm and embryo development. Endosperm metabolite profiling experiments indicated that pgd3 shifts redox-related metabolites and increases reducing sugars similar to starch-biosynthetis mutants. Heavy isotope-labelling experiments indicates that carbon flux into starch is altered in pgd3 mutants. Labelling experiments with a loss of cytosolic 6PGDH did not affect flux into starch. These results support the known role for plastid-localized oxPPP in oil synthesis and argue that amyloplast-localized oxPPP reactions are integral to endosperm starch accumulation in maize kernels. [ABSTRACT FROM AUTHOR]

The effects of partial defoliation on photosynthesis, whole-seedling carbon allocation, partitioning and growth were studied for two species with contrasting foliar traits. Field-grown seedlings of deciduous Japanese larch (Larix leptolepis) and evergreen red pine (Pinus resinosa) were defoliated by hand in early summer for 2 consecutive years. In the first year (1990), seedlings were defoliated by removing the distal 0, 25, 50 or 75% of each needle. In the second year (1991), seedlings were defoliated either 0 or 50%, regardless of Previous defoliation treatments. Defoliation had little effect on photosynthesis and starch concentration in whole seedlings of either species in the first year. In the second year, photosynthesis increased in both species in response to the 1991 defoliation treatment, and in red pine also increased in response to the 1990 defoliation treatment. Further, in 1991 both larch and pine had decreased whole-seedling total non-structural carbohydrate concentrations in all seedlings that were defoliated at least once over the 2-yr period. This decrease was noted mostly in the starch component of the non-structural carbohydrates, and was similar in both species. In 1991, biomass was similarly decreased in both species in response to 1991 defoliation. Both species showed overcompensation in total and component biomass in seedlings defoliated by 25% in 1990. Overall, the results do not support the widely held belief that evergreen trees substantially more affected than deciduous trees by defoliation. [ABSTRACT FROM AUTHOR]

The acid and alkaline invertases of mature leaves of Pisum sativum were partially purified and characterized prior to determining the effects of powdery mildew (Erysiphe pisi) infection on their activities. Seven days after inoculation, infection resulted in significant increases in the activities of both acid and alkaline invertases in whole leaves of cv. Onward, but a significant increase in the activity of only alkaline invertase in isolated mesophyll of cv. Argenteum. Activity of α-glucosidase was determined in leaves and it was concluded that this enzyme could not be responsible for the increased sucrose hydrolase activity observed in host tissues. Seven days after inoculation, infection caused a significant decrease in leaf starch content, a decrease in the activity of ADP-glucose pyrophosphorylase, and no significant change in the activity of a-glucan phosphorylase or content of inorganic phosphate. It was proposed that the decreased content of starch is a result of decreased starch synthesis. [ABSTRACT FROM AUTHOR]

Gas exchange, mass of carbohydrates, and turnover of carbohydrates, have been followed diurnally in barley leaf blades. Mature second leaf blades store sucrose, which occurs in at least two types of pool which turn over at different rates. Over a light-dark cycle, photosynthesis, sucrose synthesis and translocation all show appreciable changes in rate but are not obviously related; nor is the rate of translocation a function of the total concentration of sucrose in the leaf. In the dark, starch mobilization starts immediately and that of sucrose increases, maintaining the mean rate of translocation in the dark at 77 % of that in the light. Fructans are turned over but show little diurnal variability in mass. [ABSTRACT FROM AUTHOR]

While short-term growth at elevated Ca increases the rate of photosynthetic CO2 assimilation per unit leaf area in C3 plants, some studies show that this increase may not be maintained in the long term as a result of acclimation in the photosynthetic apparatus. A decrease in the amounts of Rubisco and tissue N and an increase in the amount of carbohydrates are observed, often associated with depression of photosynthesis in leaves acclimated to elevated Ca by long-term exposure.

The red marine alga Gracilaria sp. (collected on Israel's Mediterranean shore) was groget in the laboratory under controlled conditions. The effects of the medium (natural seawater or enriched seawater) and of irradiance on the following parameters were studied: growth rate, dry weight, content of pigments, EO[sub2] fixation rate, starch content, and the quality and quantity of agar. The total agar content was higher in algae grown in natural seawater than in those grown in enriched seawater and decreased only slightly with increasing irradiance. The agar composition was also different in algae grown in the two media. The starch content was higher in algae grown in natural seawater than in algae grown in enriched seawater, and in algae in both media it increased with increasing irradiance. Since the starch content in Gracilaria can reach 21% on a dry weight basis, it is important to correct for it when determining the agar content. [ABSTRACT FROM AUTHOR]

Small birch plants (Betula pendula Roth) were grown in a climate chamber at different levels of nutrient availability and at two photon flux densities. The extent to which starch storage was dependent upon nutrient availability and photon flux density was investigated. Acclimated values of starch concentration in leaves were highest at low nutrient availability and high photon flux density. Starch storage in roots was only found at the lowest nutrient availability. However, the relative rate of starch storage (starch stored per unit plant dry weight and time) was higher in plants with good nutrition. The data suggest that, at sub-optimal nutrient availability, the momentary rate of net shoot photosynthesis is unlikely to limit the structural (as opposed to carbon storage) growth of the plant. Although photosynthetic rate per unit leaf area (as measured at the growth climate) was slightly lower in plants with poor nutrient availability, photosynthetic rate per unit leaf nitrogen was higher. These data suggest a priority of leaf nitrogen usage in photosynthesis, with limiting amounts of leaf nitrogen (and possibly other nutrients) for subsequent growth processes. This argument is consistent with the higher concentrations of starch found in plants with poor nutrient availability. [ABSTRACT FROM AUTHOR]

Changes in the uptake and allocation of carbon and nitrogen, after a step-decrease in nutrient availability, were investigated in small birch (Betula pendula Roth). By demonstrating stable nutrition, before and after the decrease in nutrient supply, it was possible to eliminate the effects of plant size and age. Immediately following the step-decrease in nutrient availability, net nitrogen uptake to leaves and the relative rate of increase in shoot area tended to zero. Although photosynthetic rate per shoot area decreased, carbon uptake remained in excess of that used in structural growth and respiration. More of the excess carbon was accumulated as starch in leaves than in roots. After a lag phase, the relative rates of increase in plant dry matter, starch amount, net nitrogen uptake to leaves and shoot area development equalled that of the reduced rate of nutrient supply. It is concluded that the reduction in plant relative growth rate was much more attributable to the reduced allocation of photosynthate to leaf area growth than to the reduction in photosynthesis per shoot area. [ABSTRACT FROM AUTHOR]

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To elucidate the starch synthesis pathway and the role of this reserve in rice pollen, we characterized mutations in the plastidic phosphoglucomutase, OspPGM, and the plastidic large subunit of ADP-glucose (ADP-Glc) pyrophosphorylase, OsAGPL4 Both genes were up-regulated in maturing pollen, a stage when starch begins to accumulate. Progeny analysis of self-pollinated heterozygous lines carrying the OspPGM mutant alleles, osppgm-1 and osppgm-2, or the OsAGPL4 mutant allele, osagpl4-1, as well as reciprocal crosses between the wild type (WT) and heterozygotes revealed that loss of OspPGM or OsAGPL4 caused male sterility, with the former condition rescued by the introduction of the WT OspPGM gene. While iodine staining and transmission electron microscopy analyses of pollen grains from homozygous osppgm-1 lines produced by anther culture confirmed the starch null phenotype, pollen from homozygous osagpl4 mutant lines, osagpl4-2 and osagpl4-3, generated by the CRISPR/Cas system, accumulated small amounts of starch which were sufficient to produce viable seed. Such osagpl4 mutant pollen, however, was unable to compete against WT pollen successfully, validating the important role of this reserve in fertilization. Our results demonstrate that starch is mainly polymerized from ADP-Glc synthesized from plastidic hexose phosphates in rice pollen and that starch is an essential requirement for successful fertilization in rice., (© The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Coffee (Coffea spp.), a globally traded commodity, is a slow-growing tropical tree species that displays an improved photosynthetic performance when grown under elevated atmospheric CO2 concentrations ([CO2]). To investigate the mechanisms underlying this response, two commercial coffee cultivars (Catuaí and Obatã) were grown using the first free-air CO2 enrichment (FACE) facility in Latin America. Measurements were conducted in two contrasting growth seasons, which were characterized by the high (February) and low (August) sink demand. Elevated [CO2] led to increases in net photosynthetic rates (A) in parallel with decreased photorespiration rates, with no photochemical limitations to A. The stimulation of A by elevated CO2 supply was more prominent in August (56% on average) than in February (40% on average). Overall, the stomatal and mesophyll conductances, as well as the leaf nitrogen and phosphorus concentrations, were unresponsive to the treatments. Photosynthesis was strongly limited by diffusional constraints, particularly at the stomata level, and this pattern was little, if at all, affected by elevated [CO2]. Relative to February, starch pools (but not soluble sugars) increased remarkably (>500%) in August, with no detectable alteration in the maximum carboxylation capacity estimated on a chloroplast [CO2] basis. Upregulation of A by elevated [CO2] took place with no signs of photosynthetic downregulation, even during the period of low sink demand, when acclimation would be expected to be greatest., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

The harlequin mutant encodes subunit B of plant-specific topoisomerase VI. Transcriptomics showed synergistic effects on expression of adjacent genes, suggesting a broader role in chromatin remodelling during development and stress responses.Plant growth is continuous and modular, a combination that allows morphogenesis by cell division and elongation and serves to facilitate adaptation to changing environments. The pleiotropic phenotypes of the harlequin (hlq) mutant, isolated on the basis of ectopic expression of the abscisic acid (ABA)- and auxin-inducible proDc3:GUS reporter gene, were previously characterized. Mutants are skotomorphogenic, have deformed and collapsed epidermal cells which accumulate callose and starch, cell walls abundant in pectins and cell wall proteins, and abnormal and reduced root hairs and leaf trichomes. hlq and two additional alleles that vary in their phenotypic severity of starch accumulation in the light and dark have been isolated, and it is shown that they are alleles of bin3/hyp6/rhl3/Topoisomerase6B. Mutants and inhibitors affecting the cell wall phenocopy several of the traits displayed in hlq. A microarray analysis was performed, and coordinated expression of physically adjacent pairs/sets of genes was observed in hlq, suggesting a direct effect on chromatin. Histones, WRKY and IAA/AUX transcription factors, aquaporins, and components of ubiquitin-E3-ligase-mediated proteolysis, and ABA or biotic stress response markers as well as proteins involved in cellular processes affecting carbon partitioning into secondary metabolites were also identified. A comparative analysis was performed of the hlq transcriptome with other previously published TopoVI mutant transcriptomes, namely bin3, bin5, and caa39 mutants, and limited concordance between data sets was found, suggesting indirect or genotype-specific effects. The results shed light on the molecular mechanisms underlying the det/cop/fus-like pleiotropic phenotypes of hlq and support a broader role for TopoVI regulation of chromatin remodelling to mediate development in response to environmental and hormonal signals. [ABSTRACT FROM AUTHOR]

The article presents a research on the impact of starch bioengineering on cereal grain germination and seedling establishment as of 2014. The topics discussed include role of seed germination in plant propagation, role of starch granule structure in germination of seeds, and degradation of beta glucan in hyperphosphorylated (HP) starch.

In plants, drought stress is a major growth limiting factor causing cell water loss through open stomata. In this study, guard cell-specific transcripts from drought-stressed Arabidopsis plants were analysed and a down-regulation of β-amylase 1 (BAM1) was found. In previous studies, BAM1 was shown to be involved in stomatal starch degradation under ambient conditions. Impaired starch breakdown of bam1 mutant plants was accompanied by decreased stomatal opening. Here, it is shown that drought tolerance of bam1 mutant plants is improved as compared with wild-type controls. Microarray analysis of stomata-specific transcripts from bam1 mutant plants revealed a significant down-regulation of genes encoding aquaporins, auxin- and ethylene-responsive factors, and cell-wall modifying enzymes. This expression pattern suggests that reduced water uptake and limited cell wall extension are associated with the closed state of stomata of bam1 mutant plants. Together these data suggest that regulation of stomata-specific starch turnover is important for adapting stomata opening to environmental needs and its breeding manipulation may result in drought tolerant crop plants., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Global warming causes night temperature (NT) to increase faster than day temperature in the tropics. According to crop growth models, respiration incurs a loss of 40-60% of photosynthate. The thermal sensitivity of night respiration (R(n)) will thus reduce biomass. Instantaneous and acclimated effects of NT on R(n) of leaves and seedlings of two rice cultivars having a variable level of carbohydrates, induced by exposure to different light intensity on the previous day, were investigated. Experiments were conducted in a greenhouse and growth chambers, with R(n) measured on the youngest fully expanded leaves or whole seedlings. Dry weight-based R(n) was 2.6-fold greater for seedlings than for leaves. Leaf R(n) was linearly related to starch (positive intercept) and soluble sugar concentration (zero intercept). Increased NT caused higher R(n) at a given carbohydrate concentration. The change of R(n) at NT increasing from 21 °C to 31 °C was 2.4-fold for the instantaneous response but 1.2- to 1.7-fold after acclimation. The maintenance component of R(n) (R(m)'), estimated by assimilate starvation, averaged 28% in seedlings and 34% in leaves, with no significant thermal effect on this ratio. The acclimated effect of increased NT on R(m)' across experiments was 1.5-fold for a 10 °C increase in NT. No cultivar differences were observed in R(n) or R(m)' responses. The results suggest that the commonly used Q10=2 rule overestimates thermal response of respiration, and R(n) largely depends on assimilate resources., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)