Mature Grains Research Articles

Effects of low temperature at stem elongation stage on the development, morphology, and physicochemical properties of wheat starch

The low temperature in spring is a meteorological problem in wheat production because it leads to yield reduction and alteration of wheat quality. In this study, an artificial low-temperature treatment (LTT) at the stem elongation stage was implemented to investigate the starch granule development and physical and chemical properties of wheat starch. Results showed that the agronomic traits of spike, such as spike length, spikelet number per spike, and grain number per spikelet, decreased after LTT. LTT promoted the development of starch granules in developing grains at 15 days post-anthesis, resulting in increased B-type granules and reduced C-type granules with an irregular shape in mature grains. The swelling power of the starch granules was reduced, but their solubility was enhanced by LTT. The proportion of the amorphous structure within the granules increased, but the crystalline component decreased after LTT, leading to a significant reduction in the relative degree of crystallinity and double- and single-helix structures. Three types of hydrolysis showed that starch in LTT was easy to hydrolyze, resulting in a high degree of hydrolysis. The findings suggest that low temperature at the stem elongation stage can not only reduce the yield parameters of spike but also alter starch accumulation, thereby affecting the processability and structure characteristics of starch in wheat grains.

Proteome consistency of the aleurone layer in grain of major wheat species grown over different years

Background: Aleurone layer (AL), being a living cell layer among the peripheral layers of the grain structure obtained after milling wheat, is rich in, vitamins, minerals, and antioxidants potentially nutritional value of the flour. Objectives: To isolate AL in the mature grain of the three major species; Common wheat (CW), Durum wheat (DW), and Einkorn wheat (EW) that were grown at two different years as well as to analyze and compare their proteomes revealed through two-dimensional electrophoresis (2DE) and image analysis. Methods: The AL was hand dissected and unicellular purity verified using scanning electron microscopy. AL proteins were separated using IEF pH3-10 X SDS-PAGE then Coomassie-stained. The gels were scanned and the images were compared using the same spot (Nonlinear Dynamics) and were proteins identified using mass spectrometry and database interrogation. Results: For CW and DW samples, no significant quantitative or qualitative differences were observed between the AL proteome in the two years. However, a few quantitative differences were revealed between EW for AL of 2006 and 2007. The identified proteins were classified in the carbohydrate pathway and stress defense response. Conclusion: This remarkable stability over environmental growing conditions strengthens the need to pay greater attention to this unicellular living cell of the wheat grain. Keywords: Wheat, durum, einkorn, aleurone layer, metabolic pathways.

Temporal and spatial variations of carbon isotope signature reveal substantial contribution of bracts and internode assimilates to grain filling of japonica rice

Carbon isotope composition (δ13C) of a plant organ is an inherent signature reflecting its physiological property, and thus is used as an integrative index in crop breeding. It is also a non-intrusive method for quantifying the relative contribution of different source organs to grain filling in cereals. Using the samples collected from two-year field and pot experiments with two nitrogen (N) fertilization treatments, we investigated the temporal and spatial variations of δ13C in source organs of leaf, sheath, internode, and bracts, and in sink organ grain. Constitutive nature of δ13C was uncovered, with an order of leaf (−27.84‰) < grain (−27.82‰) < sheath (−27.24‰) < bracts (−26.81‰) < internode (−25.67‰). For different positions of individual organs within the plant, δ13C of the leaf and sheath presented a diminishing trend from the top (flag leaf and its sheath) to the bottom (the last leaf in reverse order and its sheath). No obvious pattern was found for the internode. For temporal variations, δ13C of the leaf and sheath had a peak (the most negative) at 10 days after anthesis (DAA), whereas that of the bracts showed a marked increase at the time point of anthesis, implying a transformation from sink to source organ. By comparing the δ13C in its natural abundance in the water-soluble fractions of the sheath, internode, and bracts with the δ13C in mature grains, the relative contribution of these organs to grain filling was assessed. With reference to the leaf, the internode accounted for as high as 32.64% and 42.56% at 10 DAA and 20 DAA, respectively. Meanwhile, bracts presented a larger contribution than the internode, with superior bracts being higher than inferior bracts. In addition, N topdressing reduced the contribution of the internode and bracts. Our findings clearly proved the actual significance of non-foliar organs of the internode and bracts for rice yield formation, thus extending our basic knowledge of source and sink relations.

Determination of Profenofos Residues using LC-MS/MS and Its Dissipation Kinetics in Pigeonpea Pods

Background: Pigeonpea is a drought resistant legume crop, cultivated in semiarid tropical and subtropical regions of the world mainly for its protein enriched seeds. Insect pests are major biotic constraints implicating yield losses of staggering dimensions. Profenofos is being used for management of pigeonpea pod borer and studying the pattern of dissipation, residual occurrence and hazard index for consumption of pigeonpea grain contaminated with profenofos is very important. Methods: A simple, sensitive and reproducible method for analysis of profenofos in pigeonpea green pods and dry grain was standardized and validated using liquid chromatography tandem mass spectrometry (LC-MS/MS) with electro spray ionization (ESI+). Modified QuEChERS methods with 1 % ethyl acetate in acetonitrile involved in the extraction of profenofos residues from green pods and mature dry grains. Results: The limit of detection and limit of quantification (LOD and LOQ) were 0.002 and 0.006 µgg-1, respectively. The recovery ranges from 88.75 to 101.36 % for the green pods and 88.34 to 98.77 % for mature dry grains with relative standard deviation (RSD) was in the range of 0.99 to 4.05 %. The field study was conducted to investigate the dissipation kinetics of profenofos in pigeonpea. Two applications of profenofos 50 % EC at 500 and 1000 g a.i.ha-1 at 15 days intervals in pigeonpea at the time of pod formation recorded initial deposits of 20.28 and 41.64 ìgg-1 in the green pod, respectively. At15 days after application, residues gradually dissipated to the level of 0.78 and 1.98 µg g-1 accounting to the loss of 96.15 and 95.58 % at 500 and 1000 g a.i. ha-1, respectively. The half-life values were 5.18 and 5.93 days. Hazard index (HI) was found less than 1 at 25th and 35th day after application at 500 and 1000 g a. i. ha-1, respectively.

Bioactive Compounds in the Peripheral Layers of Barley and Triticale Species in the Mature Grain Cultivated in Algeria

The present study designed to determine in compositions of peripheral layer (PL) from barley and triticale. The peripheral layer is a co-product of the grain mill, it represents with the flour and the germ one of the three fractions of the milling, it is used for the chemical protection of the endosperm and the germ. Phytochemicals (phenolic compounds, vitamins and minerals) are beneficial for the health of consumers and are found abundantly in the peripheral layer of cereals. The objective of our work consists an evaluation of the phytochemical value for peripheral layers, the evaluation of the antioxidant content and the antioxidant activity of two varieties of two species of cereal in mature grain: triticale (Ksar Sbahi, Beni Haroun) and barley (Fouara, Saida); from two different regions (Sidi Bel Abbes and Constantine). Finally a comparative study was found in this work. The results obtained show that the variety of each species Triticale (Ksar Sbahi), barley (Fouara) have the highest content of polyphenol and flavonoid (0.027 mg (EAG)/g; 0.019 mg EC/g) and (0.012 mg (EAG)/g; 0.013 mg EC/g), respectively, for the antioxidant activity barley Fouara 1.91 mg/ml shows the best activity against the DPPH radical, a high level of minerals has been observed for the triticale species and a higher level of sodium for the Fouara variety of barley 33.78 mg/l. We are planning additional studies to better characterize the nature of the polyphenolic compounds existing in different histological parts of the wheat grain.&#x0D; Keywords: Barley, Triticale, Peripheral layer, Polyphenols, Antioxidant activity,

Genetic variation and heritability of grain protein deviation in European wheat genotypes

There is a well-established negative relationship between the yield and the concentration of protein in the mature wheat grain. However, some wheat genotypes consistently deviate from this relationship, a phenomenon known as Grain Protein Deviation (GPD). Positive GPD is therefore of considerable interest in relation to reducing the requirement for nitrogen fertilization for producing wheat for breadmaking. We have carried out two sets of field experiments on multiple sites in South East England. The first set comprised 11 field trials of 6 cultivars grown over three years (2008-2011) and the second comprised 9 field trials of 40 genotypes grown over two years (2015-2017) and 5 field trials of 30 genotypes grown in a single year (2017-2018). All trials comprised three replicate randomized plots of each genotype and nutrient regime. These studies showed strong genetic variation in GPD, which also differed in stability between genotypes, with cultivars bred in the UK generally having higher GPD and higher stability than those bred in other European countries. The heritability of GPD was estimated as 0.44, based on data from the field trials of 30 and 40 genotypes. The largest component contributing to the genetic variance was genotype (0.30), with a smaller contribution of the interaction between genotype and year/site (0.11) and a small (but statistically significant) contribution of nitrogen level. These studies suggest that selection for GPD is a viable target for breeders.

Influences of high-level atmospheric gaseous elemental mercury on methylmercury accumulation in maize (Zea mays L.)

Maize (Zea mays L.) leaves play an important role in stomatal uptake and surface adsorption of atmospheric mercury (Hg). However, the influence of atmospheric gaseous elemental mercury (GEM) on methylmercury (MeHg) accumulation in maize plants is poorly understood. In this study, we conducted a field open-top chambers (OTCs) experiment and a soil Hg-enriched experiment to investigate the response of MeHg accumulation in maize tissues to different GEM levels in the air. Maize upper leaves had a higher average MeHg concentration (0.21 ± 0.08 ng g−1) than bottom leaves (0.15 ± 0.05 ng g−1) in the OTCs experiment, which was inconsistent with that in the soil Hg-enriched experiment (maize upper leaves: 0.41 ± 0.07 ng g−1, maize bottom leaves: 0.60 ± 0.05 ng g−1). Additionally, significantly positive correlations were found between MeHg concentrations in maize leaves and air Hg levels, suggesting that elevated air Hg levels enhanced MeHg accumulation in maize leaves, which was possibly attributed to methylation of Hg on leaf surfaces. Mature maize grains from the OTCs experiment had low MeHg concentrations (0.12–0.23 ng g−1), suggesting a low accumulation capability of MeHg by maize grains. Approximately 93–96% of MeHg and 51–73% of total Hg in maize grains were lost from the grain-filling stage to the grain-ripening stage at all GEM level treatments, implying that self-detoxification in maize grains occurred. MeHg concentrations in maize roots showed a significant linear relationship (R2 = 0.98, p < 0.01) with soil Hg levels, confirming that MeHg in maize roots is primarily from soil. This study provides a new finding that elevated air GEM levels could enhance MeHg accumulation in maize leaves, and self-detoxification may occur in maize grains. Further studies are needed to clarify these mechanisms of Hg methylation on maize leaf surfaces and self-detoxification of Hg by maize grains.

Transitions in wheat endosperm metabolism upon transcriptional induction of oil accumulation by oat endosperm WRINKLED1

BackgroundCereal grains, including wheat (Triticum aestivum L.), are major sources of food and feed, with wheat being dominant in temperate zones. These end uses exploit the storage reserves in the starchy endosperm of the grain, with starch being the major storage component in most cereal species. However, oats (Avena sativa L.) differs in that the starchy endosperm stores significant amounts of oil. Understanding the control of carbon allocation between groups of storage compounds, such as starch and oil, is therefore important for understanding the composition and hence end use quality of cereals. WRINKLED1 is a transcription factor known to induce triacylglycerol (TAG; oil) accumulation in several plant storage tissues.ResultsAn oat endosperm homolog of WRI1 (AsWRI1) expressed from the endosperm-specific HMW1Dx5 promoter resulted in drastic changes in carbon allocation in wheat grains, with reduced seed weight and a wrinkled seed phenotype. The starch content of mature grain endosperms of AsWRI1-wheat was reduced compared to controls (from 62 to 22% by dry weight (dw)), TAG was increased by up to nine-fold (from 0.7 to 6.4% oil by dw) and sucrose from 1.5 to 10% by dw. Expression of AsWRI1 in wheat grains also resulted in multiple layers of elongated peripheral aleurone cells. RNA-sequencing, lipid analyses, and pulse-chase experiments using 14C-sucrose indicated that futile cycling of fatty acids could be a limitation for oil accumulation.ConclusionsOur data show that expression of oat endosperm WRI1 in the wheat endosperm results in changes in metabolism which could underpin the application of biotechnology to manipulate grain composition. In particular, the striking effect on starch synthesis in the wheat endosperm indicates that an important indirect role of WRI1 is to divert carbon allocation away from starch biosynthesis in plant storage tissues that accumulate oil.

Variation of the Impact Aroma Compound, 2-Acetyl-1-Pyrroline, Content in Thai Fragrant Rice Plants and its Enhanced Accumulation by Soil Nutritional Elements

This study investigated the accumulation characteristics of 2-acetyl-1-pyrroline (2AP) in the Thai Jasmine rice cultivar, Khao Dawk Mali 105 (KDML 105) under different soil types and addition of soil nutritional elements. There was significant variation in the 2AP contents of rice leaves, not only among different growth stages, but also among different leaf positions at each growth stage. The highest 2AP content was seen in the third leaves at booting stage (25.10&amp;plusmn;0.90 &amp;micro;g g-1), whilst for flag leaves it was seen at mature grain stage (8.00&amp;plusmn;0.72 &amp;micro;g g-1). During the ripening stage, plants in sandy soil acquired higher 2AP content in flag leaves, spikelets, and seeds than in clay soil, with the highest 2AP content in flag leaves at 25.00&amp;plusmn;0.70 &amp;micro;g g-1. The accumulation of 2AP in basal, middle, and upper branches of panicles showed no significant differences, whereas a steady decrease in 2AP content was detected in the panicle axis and branches. The effects of individual mineral elements (B, Cr, Cu, Mg, Mn, and Se) on 2AP content was different at each growth stage. B enhanced the 2AP content by more than two-fold in the leaves at the heading stage (63.84&amp;plusmn;4.56 &amp;micro;g g-1) compared to that of the control set, followed by Mn, Cu, and Se. Similar to the above results, the 2AP content was also heightened in grains. The extended knowledge gathered in this study will assist farmers who wish to improve the fragrance qualities of their rice varieties.

Reducing nitrogen rate and increasing plant density benefit processing quality by modifying the spatial distribution of protein bodies and gluten proteins in endosperm of a soft wheat cultivar

To explore the potential ways for promoting biscuit-making quality of soft wheat, a field experiment was conducted to investigate the spatial distribution of protein bodies (PBs), gluten protein and processing quality in response to reducing nitrogen (N) rate and increasing plant density. A two-way factorial trial with three N rates (180, 120 and 0 kg ha−1) and three plant densities (180 × 104, 240 × 104 and 300 × 104 plants ha−1) was applied. The mature grains were milled into seven pearling fractions from the outermost to the innermost caryopses, denoted by P1–P7. An inward decreasing trend was found in Zeleny sedimentation volume (ZSV) of fractions from the outer (P3) to inner endosperm layer (P7). Reducing N rate and increasing plant density both improved the processing quality of all pearling fractions. Moreover, reducing N rate showed a more remarkable effect on protein quality traits than increasing plant density, and their interaction effect was significant. The decrement in ZSV was most likely ascribed to the spatial variations in gluten proteins and glutenin macropolymers (GMPs). The accumulation and aggregation of PBs in caryopses were significantly declined by reducing N rate and increasing plant density. In addition, the protein quality traits in outer endosperm showed the largest variation, followed by that in middle and inner endosperm under various N rate and plant density. Thus, the combination of reducing N rate and increasing plant density might be a practical management approach for promoting biscuit-making quality in soft wheat.

New insights into the nature of glauconite

AbstractGlauconite must be assessed as mica-rich mica-smectite R3 interstratified mineral, with the pure end-member mica also having intrinsic K-deficient chemical characteristics (K+ ~ 0.8 apfu). This assertion is in accordance with our X-ray diffraction (XRD) and high-resolution tranmission electron microscopy (HRTEM) studies and chemical analyses by electron probe microanalysis (EPMA) of mature glauconites in Cenozoic Antarctic sediments that indicate that: (1) It consists of a glauconite-smectite (R3 ordered) mixed-layer silicate, composed mainly of mica-type layers (&amp;gt;90%), but displaying slightly different proportions of Fe(III)-smectite layers (&amp;lt;10%). (2) More mature glaucony grains are characterized by major K+ and VIFe2+ (mica layers) and minor VIFe3+ (smectite layers) content in the interstratified glauconite-smectite. (3) Potassium is stabilized at the interlayer site by the octahedrally coordinated Fe2+. (4) Microtexture of the glauconite crystals are comparable with those of other micas and illite minerals, with straight, defect-free lattice fringes of ~10 Å spacings glauconite packets characteristic of mica with minor interstratified poorly crystalline smectite layers. In addition, our new findings give insights into the glauconitization process and at the same time investigate the potassium-deficient character of the dioctahedral mica “glauconite.” These findings show that glauconite crystallizes by a layer-growth mechanism at the expense of a poorly crystalline smectite precursor and that smectiteto-glauconite transformations are accompanied by a gradually higher octahedral charge deficiency (Fe2+/Fe3+) stabilized by K+ uptake into the interlayer sheet.

High post-anthesis temperature effects on bread wheat (Triticum aestivum L.) grain transcriptome during early grain-filling

BackgroundHigh post-anthesis (p.a) temperatures reduce mature grain weights in wheat and other cereals. However, the causes of this reduction are not entirely known. Control of grain expansion by the maternally derived pericarp of the grain has previously been suggested, although this interaction has not been investigated under high p.a. temperatures. Down-regulation of pericarp localised genes that regulate cell wall expansion under high p.a. temperatures may limit expansion of the encapsulated endosperm due to a loss of plasticity in the pericarp, reducing mature grain weight. Here the effect of high p.a. temperatures on the transcriptome of the pericarp and endosperm of the wheat grain during early grain-filling was investigated via RNA-Seq and is discussed alongside grain moisture dynamics during early grain development and mature grain weight.ResultsHigh p.a. temperatures applied from 6-days after anthesis (daa) and until 18daa reduced the grain’s ability to accumulate water, with total grain moisture and percentage grain moisture content being significantly reduced from 14daa onwards. Mature grain weight was also significantly reduced by the same high p.a. temperatures applied from 6daa for 4-days or more, in a separate experiment. Comparison of our RNA-Seq data from whole grains, with existing data sets from isolated pericarp and endosperm tissues enabled the identification of subsets of genes whose expression was significantly affected by high p.a. temperature and predominantly expressed in either tissue. Hierarchical clustering and gene ontology analysis resulted in the identification of a number of genes implicated in the regulation of cell wall expansion, predominantly expressed in the pericarp and significantly down-regulated under high p.a. temperatures, including endoglucanase, xyloglucan endotransglycosylases and a β-expansin. An over-representation of genes involved in the ‘cuticle development’ functional pathway that were expressed in the pericarp and affected by high p.a. temperatures was also observed.ConclusionsHigh p.a. temperature induced down-regulation of genes involved in regulating pericarp cell wall expansion. This concomitant down-regulation with a reduction in total grain moisture content and grain weight following the same treatment period, adds support to the theory that high p.a. temperatures may cause a reduction in mature grain weight as result of decreased pericarp cell wall expansion.

Genetic dissection of grain water content and dehydration rate related to mechanical harvest in maize

BackgroundThe low grain water content (GWC) at harvest is a prerequisite to mechanical harvesting in maize, or otherwise would cause massive broken kernels and increase drying costs. The GWC at harvest in turn depends on GWC at the physiological maturity (PM) stage and grain dehydration rate (GDR). Both GWC and GDR are very complex traits, governed by multiple quantitative trait loci (QTL) and easily influenced by environmental conditions. So far, a number of experiments have been conducted to reveal numbers of GWC and GDR QTL, however, very few QTL have been confirmed, and no QTL has been fine-mapped or even been cloned.ResultsWe demonstrated that GWCs after PM were positively correlated with GWC at PM, whereas negatively with GDRs after PM. With a recombinant inbred line (RIL) population, we identified totally 31 QTL related to GWC and 17 QTL related to GDR in three field trials. Seven GWC QTL were consistently detected in at least two of the three field trials, each of which could explain 6.92–24.78% of the total GWC variation. Similarly, one GDR QTL was consistently detected, accounting for 9.44–14.46% of the total GDR variation. Three major GWC QTL were found to overlap with three GDR QTL in bins 1.05/06, 2.06/07, and 3.05, respectively. One of the consistent GWC QTL, namely qGwc1.1, was fine-mapped from a 27.22 Mb to a 2.05 Mb region by using recombinant-derived progeny test. The qGwc1.1 acted in a semi-dominant manner to reduce GWC by 1.49–3.31%.ConclusionsA number of consistent GWC and GDR QTL have been identified, and one of them, QTL-qGwc1.1, was successfully refined into a 2.05 Mb region. Hence, it is realistic to clone the genes underlying the GWC and GDR QTL and to make use of them in breeding of maize varieties with low GWC at harvest.

INFLUENCE OF CULTIVATION DEGREE OF SOD-PODZOLIC SOIL ON RESPONSIVENESS OF SOWING PEAS TO NITROGEN NUTRITION LEVEL

The article presents the results of a vegetation experiment on studying an effect of increasing doses of nitrogen (factor С - N0; No.o5; No.io; N015; No.2o; N0,25 g/kg of absolutely dry soil) and pre-sowing inoculation of seeds with biological preparation "Risotorphine" (factor В - no inoculation; by inoculation) on the formation of vegetative mass and grain yield ofpeas at cultivating in the conditions of a poorly cultivated (factor A0) and of a medium cultivated (factor A f sod-podzolic soil. Cultivation degree of soil was expressed by such criteria as power of an arable horizon, value of metabolic acidity and content of mobile phosphorus, a degree of saturation of soil with bases. For experience tab there were used Mitscher-lich cups with a capacity of 5 kg of absolutely dry soil (a.d.s.), in 16 repetitions of options. The experiments were conducted in the conditions of vegetation site on the territory of University Scientific Centre "Lipogorie" of FSBEI Perm GATA, guided by a science-based methodology. When harvesting peas for a green mass more intensive development and productivity of plants (23.3 and 58.9, 40.0, 78.8 g/cup, respectively) in the phase of stem branching and budding a beginning offlowering that is recorded for its use on the background of inoculation, usage of mineral nitrogen in a dose of 0.10 g/kg on a poorly cultivated soil and 0.15 g/kg a.d.s. on a medium cultivated soil. Applying of higher doses of nitrogen has a depressing effect on development of assimilating surface of pea plants on a poorly and a medium cultivated soil. When raising pea plants before harvest maturity of grain: in the conditions of a poorly cultivated soil for yield at the level of 7.92 g/cup, the process of carrying on only an inoculation of seed with microbial preparation "Rizotorfin" can be considered; in the medium cultivated soil varieties, plant peas impose higher requirements for the level of mineral nutrition the maximum yield in the experiment (which 9.22 g/cup), noted at a combined use of inoculation and mineral nitrogen in a dose of 0.20 g/kg a.d.s.

Effects of Post-Anthesis Heat Waves on the Grain Quality of Seven European Wheat Varieties

Wheat is undoubtedly one of the most important crops worldwide and it is essential to study how the distinct varieties answer to heat waves associated with climatic changes, in order to design adequate wheat breeding strategies. To assess high temperature (HT) impact in wheat grain characteristics, seven commercial varieties, which have been recommended for production in Portugal, were submitted for one-week HT treatment ten days after anthesis. Firstly, predicted grain technological quality was determined by giving high scores for all varieties studied, based on the allelic compositions of genes encoding high molecular weight glutenins, granule-bound starch synthase and puroindolines. The effects of HT on transcription levels of those genes were, for the first time, evaluated in distinct wheat genotypes, in comparison with control plants. Finally, protein fraction content in mature grains were also estimated in untreated and treated plants. Immature grains from plants, maintained in control conditions, showed significant intervarietal differences in transcription levels of genes associated with grain quality traits, a variability that was significantly reduced in grains from HT treated plants. On the other hand, the influence of HT in mature grain protein-fractions and in gliadin/glutenin ratios revealed intervarietal diversity, even with opposite effects in some varieties. The present study, therefore, discloses marked variability in parameters associated with flour quality between the wheat varieties analyzed, which are differentially affected by HT treatments, similar to heat waves frequently observed in climate change scenarios.

TubZIP28, a novel bZIP family transcription factor from Triticum urartu, and TabZIP28, its homologue from Triticum aestivum, enhance starch synthesis in wheat.

Starch in wheat grain provides humans with carbohydrates and influences the quality of wheaten food. However, no transcriptional regulator of starch synthesis has been identified first in common wheat (Triticum aestivum) due to the complex genome. Here, a novel basic leucine zipper (bZIP) family transcription factor TubZIP28 was found to be preferentially expressed in the endosperm throughout grain-filling stages in Triticum urartu, the A genome donor of common wheat. When TubZIP28 was overexpressed in common wheat, the total starch content increased by c. 4%, which contributed to c. 5% increase in the thousand kernel weight. The grain weight per plant of overexpression wheat was also elevated by c. 9%. Both in vitro and in vivo assays showed that TubZIP28 bound to the promoter of cytosolic AGPase and enhanced both the transcription and activity of the latter. Knockout of the homologue TabZIP28 in common wheat resulted in declines of both the transcription and activity of cytosolic AGPase in developing endosperms and c. 4% reduction of the total starch in mature grains. To the best of our knowledge, TubZIP28 and TabZIP28 are transcriptional activators of starch synthesis first identified in wheat, and they could be superior targets to improve the starch content and yield potential of wheat.

Allelic Variants of CRISPR/Cas9 Induced Mutation in an Inositol Trisphosphate 5/6 Kinase Gene Manifest Different Phenotypes in Barley.

Inositol trisphosphate 5/6 kinases (ITPK) constitute a small group of enzymes participating in the sequential phosphorylation of inositol phosphate to inositol hexakisphosphate (IP6), which is a major storage form of phosphate in cereal grains. The development of lines with reduced IP6 content could enhance phosphate and mineral bioavailability. Moreover, plant ITPKs participate in abiotic stress signaling. To elucidate the role of HvITPK1 in IP6 synthesis and stress signaling, a barley itpk1 mutant was created using programmable nuclease Cas9. Homozygous single bp insertion and deletion mutant lines were obtained. The mutants contained altered levels of phosphate in the mature grains, ranging from 65% to 174% of the wild type (WT) content. Homozygous mutant lines were tested for their response to salinity during germination. Interestingly, insertion mutant lines revealed a higher tolerance to salinity stress than deletion mutants. Mature embryos of an insertion mutant itpk1-2 and deletion mutant itpk1-33 were cultivated in vitro on MS medium supplemented with NaCl at 50, 100, and 200 mM. While both mutants grew less well than WT on no or low salt concentrations, the itpk1-2 mutant was affected less than the WT and itpk33 when grown on the highest NaCl concentration. The expression of all ITPKs was induced in roots in response to salt stress. In shoots, the differential effect of high salt on IPTK expression in the two iptk1 mutants was consistent with their different sensitivities to salt stress. The results extend the evidence for the involvement of ITPK genes in phosphate storage and abiotic stress signaling.

Seed Coating and Rice Grain Stickiness

The quality concept for cooked rice (Oryza sativa L.) varies according to customers culture and habits, varying from stickier, in Asia, to looser grains, more appreciated in South America. This parameter, no matter the taste, is an important factor in the evaluation of what constitutes a good rice grain. Higher grain stickiness is associated not only with lower amylose content, but also with amylopectin chain length and the net of proteins reinforced by intra and intermolecular disulfide bonds around the rice starch granule. Therefore, the present study compared four rice genotypes and the effectiveness of seed zinc coating treatments: T0 (without zinc sulfate) and TZnSO4 (with 8.81 g of ZnSO4.7H2O. kg−1 of seeds). Here we show that both treatments affect transcript accumulation of important sulfur-metabolism-enzymes. However, the higher levels of transcripts from these genes did not result in higher cysteine or serine levels. The adhesiveness of cooked mature rice grains is greatly impacted by genotype, but no evidence that transcript up-regulation could be associated to stickiness.

Characterising avenin-like proteins (ALPs) from albumin/globulin fraction of wheat grains by RP-HPLC, SDS-PAGE, and MS/MS peptides sequencing

BackgroundWheat grain avenin-like proteins (ALPs) belong to a recently discovered class of wheat grain storage protein. ALPs in wheat grains not only have beneficial effects on dough quality but also display antifungal activities, which is a novel observation for wheat storage proteins. Previous studies have shown that ALPs are likely present in the albumin/globulin fractions of total protein extract from wheat flour. However, the accumulation characteristics of these ALPs in the mature wheat grain remains unknown.ResultsIn the present study, a total of 13 ALPs homologs were isolated and characterized in the albumin/globulin fractions of the wheat protein extract. A combination of multiple techniques including RP-HPLC, SDS-PAGE, MALDI-TOF and peptide sequencing were used for accurate separation and identification of individual ALP homolog. The C-terminal TaALP-by-4AL/7DS, TaALP-by-4AL/7AS/7DS, TaALP-bx/4AL/7AS/7DS, TaALP-ay-7DS, TaALP-ay-4AL, TaALP-ax-4AL, TaALP-ax-7AS, and TaALP-ax-7DS, were separated as individual protein bands from wheat flour for the first time. These unique ALPs peptides were mapped to the latest wheat genome assembly in the IWGSC database. The characteristic defence related proteins present in albumin and globulin fractions, such as protein disulfide-isomerase (PDI), grain softness protein (GSP), alpha-amylase inhibitors (AAIs) and endogenous alpha-amylase/subtilisin inhibitor were also found to co-segregate with these identified ALPs, avenin-3 and α-gliadins. The molecular weight range and the electrophoresis segregation properties of ALPs were characterised in comparison with the proteins containing the tryp_alpha_amyl domain (PF00234) and the gliadin domain (PF13016), which play a role in plant immunity and grain quality. We examined the phylogenetic relationships of the AAIs, GSP, avenin-3, α-gliadins and ALPs, based on the alignment of their functional domains. MALDI-TOF profiling indicated the occurrence of certain post-translations modifications (PTMs) in some ALP subunits.ConclusionsWe reported for the first time the complete profiling of ALPs present in the albumin/globulin fractions of wheat grain protein extracts. We concluded that majority of the ALPs homologs are expressed in wheat grains. We found clear evidence of PTMs in several ALPs peptides. The identification of both gliadin domain (PF13016) and Tryp_alpha_amyl domain (PF00234) in the mature forms of ALPs highlighted the multiple functional properties of ALPs in grain quality and disease resistance.

Exome sequencing of bulked segregants identified a novel TaMKK3-A allele linked to the wheat ERA8 ABA-hypersensitive germination phenotype

Key messageUsing bulked segregant analysis of exome sequence, we fine-mapped the ABA-hypersensitive mutant ERA8 in a wheat backcross population to the TaMKK3-A locus of chromosome 4A.Preharvest sprouting (PHS) is the germination of mature grain on the mother plant when it rains before harvest. The ENHANCED RESPONSE TO ABA8 (ERA8) mutant increases seed dormancy and, consequently, PHS tolerance in soft white wheat ‘Zak.’ ERA8 was mapped to chromosome 4A in a Zak/‘ZakERA8’ backcross population using bulked segregant analysis of exome sequenced DNA (BSA-exome-seq). ERA8 was fine-mapped relative to mutagen-induced SNPs to a 4.6 Mb region containing 70 genes. In the backcross population, the ERA8 ABA-hypersensitive phenotype was strongly linked to a missense mutation in TaMKK3-A-G1093A (LOD 16.5), a gene associated with natural PHS tolerance in barley and wheat. The map position of ERA8 was confirmed in an ‘Otis’/ZakERA8 but not in a ‘Louise’/ZakERA8 mapping population. This is likely because Otis carries the same natural PHS susceptible MKK3-A-A660S allele as Zak, whereas Louise carries the PHS-tolerant MKK3-A-C660R allele. Thus, the variation for grain dormancy and PHS tolerance in the Louise/ZakERA8 population likely resulted from segregation of other loci rather than segregation for PHS tolerance at the MKK3 locus. This inadvertent complementation test suggests that the MKK3-A-G1093A mutation causes the ERA8 phenotype. Moreover, MKK3 was a known ABA signaling gene in the 70-gene 4.6 Mb ERA8 interval. None of these 70 genes showed the differential regulation in wild-type Zak versus ERA8 expected of a promoter mutation. Thus, the working model is that the ERA8 phenotype results from the MKK3-A-G1093A mutation.