Mechanism of maltogenic α-amylase modification on barley granular starches spanning the full range of amylose.

Amylopectin (AP)-only (APBS), normal (NBS), and amylose (AM) only (AOBS) barley starches were selected here to investigate catalysis pattern of maltogenic α-amylase (MA) on hydrolyzing AP and AM granular starches. MA shortened starch side chains with degree of polymerization (DP) 11-30. MA-treated APBS exhibited porous granular structures and dramatically increased degree of branching (DB, 17-20 %), and reduced ordered degrees, suggesting high hydrolysis and transglycosylation activities of MA.

Beneficial glycaemic effects of high-amylose barley bread compared to wheat bread in type 2 diabetes.

Background: Cereals foods with a high content of dietary fibres or amylose have potential to lower postprandial glucose levels. Optimisation of cereal foods may improve management of type 2 diabetes (T2D).

Methods: We investigated the impact on 4 h postprandial glucose responses given as incremental area under curve (iAUC) of bread made of either 50% RNAi-based (genetically modified) amylose-only barley flour (AmOn) (and 50% wheat flour), 50% hulless barley flour (and 50% wheat flour) or 75% hulless barley (and 25% wheat flour) in subjects with T2D compared with 100% wheat flour bread.

Prehistoric Plant Exploitation and Domestication: An Inspiration for the Science of De Novo Domestication in Present Times.

De novo domestication is a novel trend in plant genetics, where traits of wild or semi-wild species are changed by the use of modern precision breeding techniques so that they conform to modern cultivation. Out of more than 300,000 wild plant species, only a few were fully domesticated by humans in prehistory. Moreover, out of these few domesticated species, less than 10 species dominate world agricultural production by more than 80% today.

The effects of drought treatments on biosynthesis and structure of maize starches with different amylose content.

We investigated the effects of drought stress (DS) on maize varieties with different amylose content (AC). In starches with AC of 33 %, DS increased the contents of amylopectin (AP) chains with a degree of polymerization (DP) > 36 and decreased the AP chains with DP ≤ 36, while the AC was unchanged. DS decreased the crystallinity, the thickness of both amorphous and crystalline lamellae, and average granular size.

Nano-encapsulation of polyphenols in starch nanoparticles: fabrication, characterization and evaluation.

Nanoparticles are more promising than microcapsules as drug carriers because they can be absorbed directly by intestinal epithelial cells, significantly increasing the uptake and bioaccessibility of polyphenols. Our study aimed to use catechin (CC), epicatechin (EC) and proanthocyanidin (PAC) adsorption onto tapioca starch nanoparticles (TSNs), which were prepared by a physical method. These TSN loaded-polyphenols were subjected to adsorption kinetic, adsorption isotherm, adsorption capacity, antioxidant activity, and release analyses.

Different genetic strategies to generate high amylose starch mutants by engineering the starch biosynthetic pathways.

This review systematically documents the major different strategies of generating high-amylose (HAS) starch mutants aiming at providing high resistant starch, by engineering the starch biosynthesis metabolic pathways. We identify three main strategies based on a new representation of the starch structure: 'the building block backbone model': i) suppression of starch synthases for reduction of amylopectin (AP) side-chains; ii) suppression of starch branching enzymes (SBEs) for production of AM-like materials; and iii) suppression of debranching enzymes to restrain the transformation from over-branched pre-AP to more ordered AP. From a biosynthetic perspective, AM generated through the second strategy can be classified into two types: i) normal AM synthesized mainly by regular expression of granule-bound starch synthases, and ii) modified linear AP chains (AM-like material) synthesized by starch synthases due to the suppression of starch branching enzymes.

High-amylose starch: Structure, functionality and applications.

Starch with a high amylose (AM) content (high AM starch, HAS) has attracted increasing research attention due to its industrial application potential, such as functional foods and biodegradable packaging. In the past two decades, HAS structure, functionality, and applications have been the research hotspots. However, a review that comprehensively summarizes these areas is lacking, making it difficult for interested readers to keep track of past and recent advances.

Changes in spatiotemporal protein and amino acid gradients in wheat caryopsis after N-topdressing.

Wheat grain nitrogen content displays large variations within different pearling fractions of grains because of radial gradients in the protein content. We identified how spatiotemporal mechanisms regulate this. The protein gradients emerged clearly at 19 days after anthesis, with the highest N content in aleurone and seed coat, followed by outer endosperm, whereas the lowest was in middle and inner endosperm.

Expression of starch-binding factor CBM20 in barley plastids controls the number of starch granules and the level of CO2 fixation.

The biosynthesis of starch granules in plant plastids is coordinated by the orchestrated action of transferases, hydrolases, and dikinases. These enzymes either contain starch-binding domain(s) themselves, or are dependent on direct interactions with co-factors containing starch-binding domains. As a means to competitively interfere with existing starch-protein interactions, we expressed the protein module Carbohydrate-Binding Motif 20 (CBM20), which has a very high affinity for starch, ectopically in barley plastids.

Phytoglobin overexpression promotes barley growth in the presence of enhanced level of atmospheric nitric oxide.

To investigate the effect of high atmospheric NO concentrations on crop plants and the role of phytoglobins under these conditions, we performed a long-term study on barley 'Golden Promise' wild type (WT), class 1 phytoglobin knockdown (HvPgb1.1-) and class 1 phytoglobin overexpression (HvPgb1.1+) lines.

Nitrogen topdressing timing modifies free amino acids profiles and storage protein gene expression in wheat grain.

Background: Nitrogen is one basic element of amino acids and grain protein in wheat. In field experiments, wheat plants were subjected to different timing of nitrogen topdressing treatments: at the stages of emergence of the top fifth leaf (TL5), top third leaf (TL3) and top first leaf (TL1) to test the regulatory effects of nitrogen topdressing timing on grain protein quality. The underlying mechanisms were elucidated by clarifying the relationship between proteolysis in vegetative organs and accumulation of amino acids in the endosperm cavity, conversion of amino acids, and storage protein synthesis in endosperm of wheat grain.

Nitrogen topdressing timing modifies the gluten quality and grain hardness related protein levels as revealed by iTRAQ.

Nitrogen fertilization regimes significantly affect both grain quality and yield. Wheat plants were subjected to different application timing of topdressed nitrogen at the emergence of the top fifth (TL5), top third (TL3) and top first leaf (TL1), respectively. The iTRAQ (isobaric tag for relative and absolute quantitation) technology was adopted to obtain the complete proteome of wheat flour and to identify the differentially expressed proteins (DEPs) as regulated by nitrogen topdressing timing.

Protein Targeting to Starch 1 is essential for starchy endosperm development in barley.

Plant starch is the main energy contributor to the human diet. Its biosynthesis is catalyzed and regulated by co-ordinated actions of several enzymes. Recently, a factor termed Protein Targeting to Starch 1 (PTST1) was identified as being required for correct granule-bound starch synthase (GBSS) localization and demonstrated to be crucial for amylose synthesis in Arabidopsis.

Differences in nutritional quality between wild and domesticated forms of barley and emmer wheat.

Grasses such as wheat and barley constitute some of the main crops currently cultivated worldwide. Cultivation of wild cereals such as Hordeum spontaneum (wild barley) and Triticum diccocoides (wild emmer) started in southwest Asia. Despite the many studies on the origins of agriculture and plant domestication, surprisingly few studies have discussed the importance of the nutritional quality of barley and emmer wheat in their evolution.

Nitric oxide-fixation by non-symbiotic haemoglobin proteins in Arabidopsis thaliana under N-limited conditions.

Nitric oxide (NO) is an important signalling molecule that is involved in many different physiological processes in plants. Here, we report about a NO-fixing mechanism in Arabidopsis, which allows the fixation of atmospheric NO into nitrogen metabolism. We fumigated Arabidopsis plants cultivated in soil or as hydroponic cultures during the whole growing period with up to 3 ppmv of NO gas.

Expression of NO scavenging hemoglobin is involved in the timing of bolting in Arabidopsis thaliana.

Plants contain three classes of hemoglobin genes of which two, class 1 and class 2, have a structure similar to classical vertebrate globins. We investigated the effect of silencing the class 1 non-symbiotic hemoglobin gene, GLB1, and the effect of overexpression of GLB1 or the class 2 non-symbiotic hemoglobin gene, GLB2, in Arabidopsis thaliana. Lines with GLB1 silencing had a significant delay of bolting and after bolting, shoots reverted to the rosette vegetative phase by formation of aerial rosettes at lateral meristems.