The importance of cereal starch production worldwide cannot be overrated. However, the qualities and resulting values of existing raw and processed starch do not fully meet future demands for environmentally friendly production of renewable, advanced biomaterials, functional foods, and biomedical additives. New approaches for starch bioengineering are needed. In this review, we discuss cereal starch from a combined universal bioresource point of view. The combination of new biotechniques and clean technology methods can be implemented to replace, for example, chemical modification. The recently released cereal genomes and the exploding advancement in whole genome sequencing now pave the road for identifying new genes to be exploited to generate a multitude of completely new starch functionalities directly in the cereal grain, converting cereal crops to production plants. Newly released genome data from cereal ancestors can potentially allow for the reintroduction of cereal traits including, for example, health‐promoting carbohydrates that may have been lost during domestication. Raw materials produced in this manner can be processed by clean enzyme‐assisted techniques or thermal treatment in combination to further functionalize or stabilize the starch polymers. Importantly, such products can be multifunctional in the sense of combined food/material or food/pharma purposes, for example, edible plastics, shape memory materials, and cycloamylose carriers and stabilizers for diverse bioactives.

Highlight textA thorough study of starch biosynthesis and deposition in a non-domesticated wild grass was performed using Brachypodium distachyon as a model.

In this study we introduce the starch-recognising carbohydrate binding module family 20 (CBM20) from Aspergillus niger for screening biological variations in starch molecular structure using high throughput carbohydrate microarray technology. Defined linear, branched and phosphorylated maltooligosaccharides, pure starch samples including a variety of different structures with variations in the amylopectin branching pattern, amylose content and phosphate content, enzymatically modified starches and glycogen were included. Using this technique, different important structures, including amylose content and branching degrees could be differentiated in a high throughput fashion. The screening method was validated using transgenic barley grain analysed during development and subjected to germination. Typically, extreme branching or linearity were detected less than normal starch structures. The method offers the potential for rapidly analysing resistant and slowly digested dietary starches.

Summary Solanum tuberosum potato lines with high amylose content were generated by crossing with the wild potato species Solanum sandemanii followed by repeated backcrossing to Solanum tuberosum lines. The trait, termed increased amylose (IAm), was recessive and present after three generations of backcrossing into S. tuberosum lines (6.25% S. sandemanii genes). The tubers of these lines were small, elongated and irregular with small and misshaped starch granules and high sugar content. Additional backcrossing resulted in less irregular tuber morphology, increased starch content (4.3%–9.5%) and increased amylose content (29%–37.9%) but indifferent sugar content. The amylose in the IAm starch granules was mainly located in peripheral spots, and large cavities were found in the granules. Starch pasting was suppressed, and the digestion‐resistant starch (RS) content was increased. Comprehensive microarray polymer profiling (CoMPP) analysis revealed specific alterations of major pectic and glycoprotein cell wall components. This complex phenotype led us to search for candidate IAm genes exploiting its recessive trait. Hence, we sequenced genomic DNA of a pool of IAm lines, identified SNPs genome wide against the draft genome sequence of potato and searched for regions of decreased heterozygosity. Three regions, located on chromosomes 3, 7 and 10, respectively, displayed markedly less heterozygosity than average. The only credible starch metabolism‐related gene found in these regions encoded the isoamylase‐type debranching enzyme Stisa1. Decreased expression of mRNA (>500 fold) and reduced enzyme activity (virtually absent from IAm lines) supported Stisa1 as a candidate gene for IAm.

Glutamine synthetase (GS) is a key nitrogen-assimilating enzyme in plants and a target for the broad-spectrum herbicide glufosinate. Understanding its kinetic and structural properties is of major agricultural importance. Spinach (Spinacia oleracea) is classified as a plant expressing only chloroplastic GS activity. We have analyzed soluble proteins in the spinach by coupling native polyacrylamide gel electrophoresis (PAGE)-activity detection, based on phosphate precipitation, with SDS-PAGE/immunoblotting. One cytosolic (GS1) isoform from the roots and two chloroplastic (GS2) isoforms expressed in leaves were resolved by native PAGE. The identity of the obtained bands was established by the application of GS-specific inhibitors, L-methionine sulfoximine and glufosinate. Examination by sodium dodecyl sulfate (SDS)-PAGE/ Western analysis with anti-GS antibodies, confirmed the identity of the active bands and revealed that both chloroplastic isoforms are composed of 44 kDa subunits, while the cytosolic isoform consists of 40 kDa subunits. The presence of more GS2 isozymes than encoded in the spinach genome is discussed in terms of posttranslational modifications