Grape and wine analysis: Oenologists to exploit advanced test kits.
Charnock, S. C. & McCleary, B. V. (2005). Revue des Enology, 117, 1-5.
It is without doubt that testing plays a pivotal role throughout the whole of the vinification process. To produce the best possible quality wine and to minimise process problems such as “stuck” fermentation or troublesome infections, it is now recognised that if possible testing should begin prior to harvesting of the grapes and continue through to bottling. Traditional methods of wine analysis are often expensive, time consuming, require either elaborate equipment or specialist expertise and frequently lack accuracy. However, enzymatic bio-analysis enables the accurate measurement of the vast majority of analytes of interest to the wine maker, using just one piece of apparatus, the spectrophotometer (see previous issue No. 116 for a detailed technical review). Grape juice and wine are amenable to enzymatic testing as being liquids they are homogenous, easy to manipulate, and can generally be analysed without any sample preparation.
Megazyme “advanced” wine test kits general characteristics and validation.
Charnock, S. J., McCleary, B. V., Daverede, C. & Gallant, P. (2006). Reveue des Oenologues, 120, 1-5.
Many of the enzymatic test kits are official methods of prestigious organisations such as the Association of Official Analytical Chemicals (AOAC) and the American Association of Cereal Chemists (AACC) in response to the interest from oenologists. Megazyme decided to use its long history of enzymatic bio-analysis to make a significant contribution to the wine industry, by the development of a range of advanced enzymatic test kits. This task has now been successfully completed through the strategic and comprehensive process of identifying limitations of existing enzymatic bio-analysis test kits where they occurred, and then using advanced techniques, such as molecular biology (photo 1), to rapidly overcome them. Novel test kits have also been developed for analytes of emerging interest to the oenologist, such as yeast available nitrogen (YAN; see pages 2-3 of issue 117 article), or where previously enzymes were simply either not available, or were too expensive to employ, such as for D-mannitol analysis.
Evaluation of Type of Process on Functional Properties and on Nutritional and Anti-nutritional Composition of Yams (Dioscorea cayenensis-rotundata).
Kouassi, N. K., Nindjin, C., Tetchi, A. F. & Amani, G. N. (2010). Journal of Food Technology, 8(4), 191-199.
The nutritional, anti-nutritional composition and functional properties of yam flours obtained from different processes with four varieties of Dioscorea cayenensis-rotundata extensively consumed in Cote d’Ivoire were evaluated. The results showed that nutritional and anti-nutritional composition of yams are lower and decrease greatly during boiling than baking. The lower values of least gelatinization concentration obtained with flour of cooked yam than raw yam flour is due to the loss of amylose which is associated with starch granules gelatinization during the cooking. This gelatinization is characterized by granule starch of high size and a heterogeneous distribution. The great solubility and the weak capacity of swelling during heating of flour of boiled yam are due to the fact that the gelatinization of starch had been higher in the boiling. This great gelatinization in boiled yam is associated to the high level of glucose rate during digestion and could induce metabolic disorders.
Submerged culture process for biomass and exopolysaccharide production by Antarctic yeast: some engineering considerations.
Vlaev, S., Rusinova-Videva, S., Pavlova, K., Kuncheva, M., Panchev, I. & Dobreva, S. (2013). Applied Microbiology and Biotechnology, 97(12), 5303-5313.
Production of biomass and extracellular polysaccharide (EPS) from psychrophilic Sporobolomyces salmonicolor AL1 in a stirred bioreactor was studied. The aspects of production technical-scale parameters, namely, bioreactor flow field, biomass and EPS production rates, oxygen mass transfer per input power, as well as important product properties, such as rheology and stability of EPS mixtures, were considered. The bioprocess was found to proceed in non-Newtonian flow with consistency coefficient rising typically to 0.03 Pa.sn and flow index declining to 0.7. Flow modeling was carried out and showed good homogenization for substrate delivery at agitation rates exceeding 400 rpm. Agitation rates lower than 400 rpm were considered counterproductive due to flow field non-uniformity. The cell density reached 5 g/l and EPS production yield reached 5.5 g/l at production rate 0.057 g EPS/l per hour (0.01 g EPS/g biomass per hour). Oxygen uptake rate and oxygen transfer rate were in the range of 0.5–1.7 mmolO2/l per hour and 2–4.7 mmolO2/l per hour, respectively. The mass transfer coefficient at reaction conditions was found to be in the rangeKLa~0.004−0.01s-1. The bioprocess biological performance was higher at moderate agitation speed and revealed biomass diminution and cell inactivation by increasing impeller revolutions and shear rate. The product EPS was found to introduce shear-thinning behavior in water solutions with apparent viscosity of up to 30 mPa.s and to stabilize 1–2 % oil-in-water emulsions improving their lipophilic properties. The emulsion dispersion index was found to be comparable with the one of Arlacel 165, the emulsifier used in cosmetic. The long-term performance of the complex cream mixtures of the glucomannan prepared in commercial format was found promising for further application.
Near‐infrared reflectance calibrations for determining sucrose content in soybean breeding using artificial reference samples.
Sato, T., Zahlner, V., Berghofer, E., Lošák, T. & Vollmann, J. (2012). Plant Breeding, 131(4), 531-534.
In food-grade soybeans for human nutrition, sucrose content is a character of interest apart from protein, because sucrose affects flavour and other soy-food properties. As determination of sucrose content through separative or enzymatic methods is not suitable for analysing large numbers of samples, the objective of this research was to develop near-infrared reflectance spectroscopy (NIRS) calibrations for rapid screening of breeding lines for sucrose. Conventional soybean samples have a sucrose content of 30–60 g/kg, whereas high-sucrose reference samples are lacking. Therefore, both natural and artificial (additional sucrose added) reference samples with a sucrose content of up to 140 g/kg were combined, and a NIRS calibration model was developed (cross-validation R2 = 0.969) for sucrose. Utilizing wavelength ranges with homogeneous performance in both natural and artificial samples, a prediction model was obtained, which suggests a stable performance of the calibration over a wide range of sucrose concentrations. Thus, identification of high-sucrose soybean introgressions should be possible in appropriate segregating populations.
Altered seed oil and glucosinolate levels in transgenic plants overexpressing the Brassica napus Shootmeristemless gene.
Elhiti, M., Yang, C., Chan, A., Durnin, D. C., Belmonte, M. F., Ayele, B. T., Tahir M. & Stasolla, C. (2012). Journal of Experimental Botany, 63(12), 4447-4461.
SHOOTMERISTEMLESS (STM) is a homeobox gene conserved among plant species which is required for the formation and maintenance of the shoot meristem by suppressing differentiation and maintaining an undetermined cell fate within the apical pole. To assess further the role of this gene during seed storage accumulation, transgenic Brassica napus (Bn) plants overexpressing or down-regulating BnSTM under the control of the 35S promoter were generated. Overexpression of BnSTM increased seed oil content without affecting the protein and sucrose level. These changes were accompanied by the induction of genes encoding several transcription factors promoting fatty acid (FA) synthesis: LEAFY COTYLEDON1 (BnLEC1), BnLEC2, and WRINKLE1 (BnWRI1). In addition, expression of key representative enzymes involved in sucrose metabolism, glycolysis, and FA biosynthesis was up-regulated in developing seeds ectopically expressing BnSTM. These distinctive expression patterns support the view of an increased carbon flux to the FA biosynthetic pathway in developing transformed seeds. The overexpression of BnSTM also resulted in a desirable reduction of seed glucosinolate (GLS) levels ascribed to a transcriptional repression of key enzymes participating in the GLS biosynthetic pathway, and possibly to the differential utilization of common precursors for GLS and indole-3-acetic acid synthesis. No changes in oil and GLS levels were observed in lines down-regulating BnSTM. Taken together, these findings provide evidence for a novel function for BnSTM in promoting desirable changes in seed oil and GLS levels when overexpressed in B. napus plants, and demonstrate that this gene can be used as a target for genetic improvement of oilseed species.
Engineering cyanobacteria to synthesize and export hydrophilic products.
Niederholtmeyer, H., Wolfstädter, B. T., Savage, D. F., Silver, P. A. & Way, J. C. (2010). Applied and Environmental Microbiology, 76(11), 3462-3466.
Metabolic engineering of cyanobacteria has the advantage that sunlight and CO2 are the sole source of energy and carbon for these organisms. However, as photoautotrophs, cyanobacteria generally lack transporters to move hydrophilic primary metabolites across membranes. To address whether cyanobacteria could be engineered to produce and secrete organic primary metabolites, Synechococcus elongatus PCC7942 was engineered to express genes encoding an invertase and a glucose facilitator, which mediated secretion of glucose and fructose. Similarly, expression of lactate dehydrogenase- and lactate transporter-encoding genes allowed lactate accumulation in the extracellular medium. Expression of the relevant transporter was essential for secretion. Production of these molecules was further improved by expression of additional heterologous enzymes. Sugars secreted by the engineered cyanobacteria could be used to support Escherichia coli growth in the absence of additional nutrient sources. These results indicate that cyanobacteria can be engineered to produce and secrete high-value hydrophilic products.
Variation and correlation of properties in different grades of maple syrup.
Singh, A. S., Jones, A. M. P. & Saxena, P. K. (2014). Plant Foods for Human Nutrition, 69(1), 50-56.
Thirty five commercial maple syrups from twelve producers in Southern Ontario were evaluated for properties including light transmittance, autofluorescence, density, pH, total soluble solids (TSS), glucose and fructose content, total phenol content, antioxidant potential and mineral content (Mg, Mn, P, Zn, Ca, K, Fe and Pb). A high degree of variability was found in many characteristics, often exceeding an order of magnitude. Syrups were categorized based on light transmission at 560 nm into amber (12), dark (13) and very dark (10) using International Maple Syrup Institute (IMSI) guidelines. No statistical differences were found among grades of syrup for density, pH, TSS, glucose, fructose, total reducing sugars, glucose:fructose ratio, magnesium, manganese or potassium. Darker syrups showed significantly higher autofluorescence, total phenol content, antioxidant potential, phosphorous, calcium and total mineral content. Significant negative correlations of percent transmission with total phenol content, antioxidant potential and total mineral content are reported. Significant positive correlations among total phenol content, antioxidant potential and total mineral content are also described. The results from this study suggest that darker syrups tend to contain more beneficial traits and may be applied in developing functional foods and value added products.
Spontaneous postharvest fermentation of açai (Euterpe oleracea) fruit.
Aguiar, F., Menezes, V. & Rogez, H. (2013). Postharvest Biology and Technology, 86, 294-299.
Açai (Euterpe oleracea) fruit (EOF) are widely commercialized in the Brazilian Amazon. These fruit contain a high bacterial load and are transported on boards stowed inside or outside the holds of small boats. In this context, postharvest parameters were assessed under conditions that simulated these two methods of EOF transport: stowage in closed polystyrene boxes, simulating the inside of cargo holds, i.e., transport in a closed system; and open baskets, simulating transport in an open environment, i.e., transport in the prow or bow of the boat. EOF suffered spontaneous fermentation of alcoholic, acetic, and lactic types in the closed system, which is the most common type of transportation of this fruit. In the closed system, there was a predominance of lactic acid bacteria over acetic acid bacteria, with 82% and 95% of the initial content of D-glucose and D-fructose being consumed, respectively, after 27 h of experiment. The weight loss reached 1.7% and there was a logarithmic decrease of the major phenolic compounds of the fruit in the closed system, with losses of 78% of cyanidin-3-rutinoside, 88% of cyanidin-3-glucoside, 78% of homorientin, and 72% of orientin after 27 h, which was higher than in the open system (58%, 66%, 73% and 62%, respectively). Analyses on EOF stowed in a closed system indicated that the respiratory rate was characteristic of a non-climacteric fruit, i.e., it showed a logarithmic decay in the production of CO2 (R2= 0.995; P < 0.05). Thus, transport in a closed system results in more drastic nutritional and functional changes on EOF than when transport is carried out in an open system, suggesting that transportation in continuous aerobic conditions and a short period of time between picking and processing are preferable.
Partial Study of Yam Tuber (Dioscorea spp.) Parts during the Growth Period.
Claver Degbeu, K., N'dri, Y. D., Fabrice Tetchi, A., Nindjin, C., N'guessan Amani, G. & Bakayoko, A. (2013). Advance Journal of Food Science & Technology, 5(9), 1120-1131.
Growing gradient into longitudinal axis of yam tuber was study through starch properties and nutritional composition of tuber parts (proximal, median and distal) during the tuberization. Two varieties of the complex D. cayenensis-rotundata (kangba and kponan) were used. Clarity, swelling and solubility, flow behavior and syneresis of starch and protein content, alcohol-soluble sugars of the flour were studies. The ash assessed by microanalysis. Starch clarity of tuber parts increased during the growth period. The proximal (56±2.06%) and median (54.5±1.09%) parts exhibited high clarity than the distal (48.2±2.56%) one. At earlier stage of tuberization, the viscosity ratio of tuber parts (var. Kponan) was weak. This indicates the possibility to use it as thickening agent in shearing sauce. Water loss decreased during the growth period for the three tuber parts. It was the same behavior for the swelling power. Concerning the nutritional composition of the flour, amount of protein did not influenced by the degree of tuber maturity. Alcohol-soluble sugars were higher at earlier stage of tuberization than at maturity of the tuber. Mineral content was appreciable at maturity than at beginning of the tuberization. The extent mineral according to their amount was: K, P, Mg and S. Starch properties such as clarity, syneresis and swelling were improved at maturity of the tuber. It was more for the proximal and median parts than the distal one. Yam tuber content a appreciable amount of protein and mineral at maturity.
Galanthamine production by Leucojum aestivum L. shoot culture in a modified bubble column bioreactor with internal sections.
Georgiev, V., Ivanov, I., Berkov, S., Ilieva, M., Georgiev, M., Gocheva, T. & Pavlov, A. (2012). Engineering in Life Sciences, 12(5), 534-543.
Shoot culture of summer snowflake (Leucojum aestivum L.) was successfully cultivated in an advanced modified glass-column bioreactor with internal sections for production of Amaryllidaceae alkaloids. The highest amounts of dry biomass (20.8 g/L) and galanthamine (1.7 mg/L) were achieved when shoots were cultured at 22°C and 18 L/(L•h) flow rate of inlet air. At these conditions, the L. aestivum shoot culture possessed mixotrophic-type nutrition, synthesizing the highest amounts of chlorophyll (0.24 mg/g DW (dry weight) chlorophyll A and 0.13 mg/g DW chlorophyll B). The alkaloids extract of shoot biomass showed high acetylcholinesterase inhibitory activity (IC50= 4.6 mg). The gas chromatography–mass spectrometry (GC/MS) profiling of biosynthesized alkaloids revealed that galanthamine and related compounds were presented in higher extracellular proportions while lycorine and hemanthamine-type compounds had higher intracellular proportions. The developed modified bubble-column bioreactor with internal sections provided conditions ensuring the growth and galanthamine production by L. aestivum shoot culture.
Sugar accumulation in roots of two grape varieties with contrasting response to water stress.
Rogiers, S. Y., Holzapfel, B. P. & Smith, J. P. (2011). Annals of Applied Biology, 159(3), 399-413.
Root sugar accumulation was studied in two grapevine varieties contrasting in tolerance to water stress. During a 10-day water withholding treatment, the drought-tolerant variety, Grenache, sustained less negative predawn and midday leaf water potentials as well as root water potential compared with the sensitive variety, Semillon. Grenache vines also maintained lower stomatal conductance and transpiration than Semillon vines throughout the drying period. In both varieties there was accumulation of sucrose in the roots and concentrations were inversely correlated to leaf and root water status. In both Grenache and Semillon, elevated root osmolality was associated with decreased soil moisture indicating that sugar accumulation may play a role in osmotic protection. Petiole xylem sap abscisic acid (ABA) concentrations increased with water deficit in both varieties and were highest for vines with the most negative root and predawn leaf water potentials. Furthermore, root sucrose concentrations were positively correlated with leaf xylem sap ABA concentrations, indicative of integration between carbohydrate metabolism and the ABA signalling system. Similar root sugar accumulation patterns between the two varieties, however, demonstrate that other factors are likely influencing the ability of the drought-tolerant variety to remain hydrated.
Carbohydrate reserve status of Malbec grapevines after several years of regulated deficit irrigation and crop load regulation.
Dayer, S., Prieto, J. A., Galat, E. & Perez Peña, J. (2013). Australian Journal of Grape and Wine Research, 19(3), 422-430.
Background and Aims: Regulated deficit irrigation (RDI) and bunch thinning are two viticultural practices applied worldwide. There is limited knowledge, however, about their combined effects on carbohydrate dynamics and accumulation. We evaluated during year 3 and 4 of the experiment the effect of 4 consecutive years of RDI and bunch thinning on carbohydrate status, vegetative and reproductive variables. Methods and Results: From 2006/07 to 2009/10, we imposed four levels of water supply [100, 60, 38 and 25% of reference evapotranspiration (ETo)] and two crop loads (100 and 50% of the bunches). We compared shoot length, flowers per inflorescence and yield in 2009/10. We also measured pruning mass and the concentration of non-structural carbohydrates in dormant wood in the winters of 2009 and 2010. Starch concentration in the trunk was reduced by severe water deficit (25 and 38% ETo) and improved by bunch thinning. Pruning mass, shoot length, flowers per inflorescence and yield were affected in vines with water applied at 25 and 38% of ETo. Conclusions: Severe water stress and high crop load reduced trunk starch concentration with no interaction between both factors, whereas the concentration of total non-structural carbohydrate was not affected. Vegetative growth and yield were reduced after 4 years of severe water stress. Significance of the Study: We provide evidence that starch concentration and carbon partitioning can be manipulated through common viticultural practices, such as irrigation and crop load.
Stem carbohydrate dynamics and expression of genes involved in fructan accumulation and remobilization during grain growth in wheat (Triticum aestivum L.) genotypes with contrasting tolerance to water stress.
Yáñez, A., Tapia, G., Guerra, F. & del Pozo, A. (2017). PloS one, 12(5), e0177667.
The genetic and physiological mechanisms underlying the relationship between water-soluble carbohydrates (WSC) and water stress tolerance are scarcely known. This study aimed to evaluate the main WSC in stems, and the expression of genes involved in fructan metabolism in wheat genotypes growing in a glasshouse with water stress (WS; 50% field capacity from heading) and full irrigation (FI; 100% field capacity). Eight wheat genotypes (five tolerant and three susceptible to water stress) were evaluated initially (experiment 1) and the two most contrasting genotypes in terms of WSC accumulation were evaluated in a subsequent experiment (experiment 2). Maximum accumulation of WSC occurred 10–20 days after anthesis. Under WS, the stress-tolerant genotype exhibited higher concentrations of WSC, glucose, fructose and fructan in the stems, compared to FI. In addition, the stress-tolerant genotype exhibited higher up-regulation of the fructan 1-fructosyltransferase B (1-FFTB) and fructan 1-exohydrolase w2 (1-FEHw2) genes, whereas the susceptible cultivar presented an up-regulation of the fructan 6-fructosyltransferase (6-SFT) and fructan 1-exohydrolase w3 (1-FEHw3) genes. Our results indicated clear differences in the pattern of WSC accumulation and the expression of genes regulating fructan metabolism between the tolerant and susceptible genotypes under WS.
Different responses of stem and soil CO2 efflux to pruning in a Chinese fir (Cunninghamia lanceolata) plantation.
Yang, Q., Liu, L., Zhang, W., Xu, M. & Wang, S. (2015). Trees, 29(4), 1207-1218.
Pruning is one of the common silvicultural practices for Chinese fir (Cunninghamia lanceolata) plantations to produce knot-free wood. However, little is known about the effects of pruning on stem and soil CO2 efflux in Chinese fir plantations. In this study, we experimentally manipulated the canopy of Chinese fir by pruning the lower 50 % of the green crown length in a Chinese fir plantation. We monitored the effects of pruning on the stem and soil CO2 efflux, stem radial growth, xylem sap flow, and nonstructural carbohydrate (NSC) concentrations. Our results showed that pruning resulted in the significant reduction of stem CO2 efflux, particularly during the growing season. Despite the removal of the lower 50 % of the green crown length, we did not observe a pronounced reduction in soil CO2 efflux and its components. Moreover, pruning had only little effect on sap flow. No significant difference was observed in the NSC concentrations between treatments in the stem cores and fine roots. We speculated that the different responses of stem and soil CO2 efflux to pruning in the Chinese fir (sprouting species) plantation may have resulted from the different carbon allocations between aboveground and belowground tissues. However, further studies are required to confirm if our findings could be applied to other tree species or ecosystems.
Could cider aroma modify cider mouthfeel properties?
Symoneaux, R., Guichard, H., Le Quéré, J. M., Baron, A. & Chollet, S. (2015). Food Quality and Preference, 45, 11-17.
The objective of this work was to evaluate whether aroma–taste interactions could occur in cider due to cognitive interactions such as a dumping effect or a congruency phenomenon. Sixteen French ciders were selected with different organoleptic characteristics. Three different tasting conditions were compared in order to evaluate the presence of aroma interactions with taste. A trained panel was first asked to assess ciders, with and without a nose clip, on four attributes: sweetness, sourness, bitterness and astringency. Secondly, they had to score the same four attributes with seven aroma attributes added. It was shown that the perception of sweetness and astringency was modified in the presence of aroma. Ciders with fruity and caramel aromatic notes were perceived sweeter contrary to ciders with hay, animal and earthy notes, which were perceived less sweet. Moreover, the aroma interaction with sweetness was sugar concentration-dependent. It occurred only in cider containing around 40 g/L of sugar. Finally, ciders were perceived more astringent when tasted without wearing a nose clip.
Effect of pre-treatments on the saccharification of pineapple waste as a potential source for vinegar production.
Roda, A., De Faveri, D. M., Giacosa, S., Dordoni, R. & Lambri, M. (2016). Journal of Cleaner Production, 112, 4477-4484.
Properly saccharified pineapple waste can be considered the chief raw material for further fermentation into vinegar, which has wider applications as a food dressing or preservative both in industry and rural communities in developing countries. Previous investigations into the use of pineapple waste as a potential source for vinegar production highlighted the optimal conditions for the enzymatic hydrolysis step and outlined the need to facilitate enzyme access for saccharification. The effects of four physical pre-treatments were investigated to reduce biomass recalcitrance. Microwave heating (MW), boiling (B), cooking at high pressure with a pressure cooker (HPC) and with an autoclave (HPA) were carried out on peel and core samples for different lengths of time. When HPA preceded the enzymatic hydrolysis, the sugar yield was 70.2 g/kgfw and 72.8 g/kgfw from pineapple peel and core, respectively. When pineapple waste was subjected to HPC, B, or MW, the sugar yield obtained was lower than 60 g/kgfw. This study outlines the most effective pre-treatment method for obtaining a satisfactory sugar yield while maintaining practical feasibility when implementing the process prior to fermentation.
The Arabidopsis thylakoid transporter PHT4; 1 influences phosphate availability for ATP synthesis and plant growth.
Karlsson, P. M., Herdean, A., Adolfsson, L., Beebo, A., Nziengui, H., Irigoyen, S., Ünnep, R., Zsiros, O., Nagy, G,. Garab, G., Aronsson, H., Versaw, W. K. & Aronsson, H. (2015). The Plant Journal, 84(1), 99-110.
The Arabidopsis phosphate transporter PHT4;1 was previously localized to the chloroplast thylakoid membrane. Here we investigated the physiological consequences of the absence of PHT4;1 for photosynthesis and plant growth. In standard growth conditions, two independent Arabidopsis knockout mutant lines displayed significantly reduced leaf size and biomass but normal phosphorus content. When mutants were grown in high-phosphate conditions, the leaf phosphorus levels increased and the growth phenotype was suppressed. Photosynthetic measurements indicated that in the absence of PHT4;1 stromal phosphate was reduced to levels that limited ATP synthase activity. This resulted in reduced CO2 fixation and accumulation of soluble sugars, limiting plant growth. The mutants also displayed faster induction of non-photochemical quenching than the wild type, in line with the increased contribution of ΔpH to the proton-motive force across thylakoids. Small-angle neutron scattering showed a smaller lamellar repeat distance, whereas circular dichroism spectroscopy indicated a perturbed long-range order of photosystem II (PSII) complexes in the mutant thylakoids. The absence of PHT4;1 did not alter the PSII repair cycle, as indicated by wild-type levels of phosphorylation of PSII proteins, inactivation and D1 protein degradation. Interestingly, the expression of genes for several thylakoid proteins was downregulated in the mutants, but the relative levels of the corresponding proteins were either not affected or could not be discerned. Based on these data, we propose that PHT4;1 plays an important role in chloroplast phosphate compartmentation and ATP synthesis, which affect plant growth. It also maintains the ionic environment of thylakoids, which affects the macro-organization of complexes and induction of photoprotective mechanisms.
Effects of Fe deficiency on the protein profile of Brassica napus phloem sap.
Gutierrez‐Carbonell, E., Lattanzio, G., Albacete, A., Rios, J. J., Kehr, J., Abadía, A., Grusak, M. A., Abadía, J. & López‐Millán, A. F. (2015). Proteomics, 15(22), 3835-3853.
The aim of this work was to study the effect of Fe deficiency on the protein profile of phloem sap exudates from Brassica napus using 2DE (IEF-SDS-PAGE). The experiment was repeated thrice and two technical replicates per treatment were done. Phloem sap purity was assessed by measuring sugar concentrations. Two hundred sixty-three spots were consistently detected and 15.6% (41) of them showed significant changes in relative abundance (22 decreasing and 19 increasing) as a result of Fe deficiency. Among them, 85% (35 spots), were unambiguously identified. Functional categories containing the largest number of protein species showing changes as a consequence of Fe deficiency were signaling and regulation (32%), and stress and redox homeostasis (17%). The Phloem sap showed a higher oxidative stress and significant changes in the hormonal profile as a result of Fe deficiency. Results indicate that Fe deficiency elicits major changes in signaling pathways involving Ca and hormones, which are generally associated with flowering and developmental processes, causes an alteration in ROS homeostasis processes, and induces decreases in the abundances of proteins involved in sieve element repair, suggesting that Fe-deficient plants may have an impaired capacity to heal sieve elements upon injury.
Mapping of quantitative trait loci for tuber starch and leaf sucrose contents in diploid potato.
Śliwka, J., Sołtys-Kalina, D., Szajko, K., Wasilewicz-Flis, I., Strzelczyk-Żyta, D., Zimnoch-Guzowska, E., Jakuczun, H. & Marczewski, W. (2016). Theoretical and Applied Genetics, 129(1), 131-140.
In the present study, using a diploid potato mapping population and Diversity Array Technology (DArT) markers, we identified twelve quantitative trait loci (QTL) for tuber starch content on seven potato chromosomes: I, II, III, VIII, X, XI, and XII. The most important QTL spanned a wide region of chromosome I (42.0-104.6 cM) with peaks at 63 and 84 cM which explained 17.6 and 19.2 % of the phenotypic variation, respectively. ADP-glucose pyrophosphorylase (AGPase) is the key enzyme for starch biosynthesis. The gene encoding the large subunit of this enzyme, AGPaseS-a, was localized to chromosome I at 102.3 cM and accounted for 15.2 % of the variance in tuber starch content. A more than 100-fold higher expression of this gene was observed in RT-qPCR assay in plants with the marker allele AGPaseS-a1334. This study is the first to report QTL for sucrose content in potato leaves. QTL for sucrose content in leaves were located on eight potato chromosomes: I, II, III, V, VIII, IX, X and XII. In 5-week-old plants, only one QTL for leaf sucrose content was detected after 8 h of darkness; four QTL were detected after 8 h of illumination. In 11-week-old plants, 6 and 3 QTL were identified after dark and light phases, respectively. Of fourteen QTL for leaf sucrose content, eleven mapped to positions that were similar to QTL for tuber starch content. These results provide genetic information for further research examining the relationships between metabolic carbon molecule sources and sinks in potato plants.