Aluminum Stress Induces Irreversible Proteomic Changes in the Roots of the Sensitive but Not the Tolerant Genotype of Triticale Seedlings.

Triticale is a wheat-rye hybrid with a higher abiotic stress tolerance than wheat and is better adapted for cultivation in light-type soils, where aluminum ions are present as Al-complexes that are harmful to plants. The roots are the first plant organs to contact these ions and the inhibition of root growth is one of the first plant reactions. The proteomes of the root apices in Al-tolerant and -sensitive plants were investigated to compare their regeneration effects following stress. The materials used in this study consisted of seedlings of three triticale lines differing in Al3+ tolerance, first subjected to aluminum ion stress and then recovered. Two-dimensional electrophoresis (2-DE) was used for seedling root protein separation followed by differential spot analysis using liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS/MS). The plants' tolerance to the stress was evaluated based on biometric screening of seedling root regrowth upon regeneration. Our results suggest that the Al-tolerant genotype can recover, without differentiation of proteome profiles, after stress relief, contrary to Al-sensitive genotypes that maintain the proteome modifications caused by unfavorable environments.

Androgenic-Induced Transposable Elements Dependent Sequence Variation in Barley.

A plant genome usually encompasses different families of transposable elements (TEs) that may constitute up to 85% of nuclear DNA. Under stressful conditions, some of them may activate, leading to sequence variation. In vitro plant regeneration may induce either phenotypic or genetic and epigenetic changes. While DNA methylation alternations might be related, i.e., to the Yang cycle problems, DNA pattern changes, especially DNA demethylation, may activate TEs that could result in point mutations in DNA sequence changes. Thus, TEs have the highest input into sequence variation (SV). A set of barley regenerants were derived via in vitro anther culture. High Performance Liquid Chromatography (RP-HPLC), used to study the global DNA methylation of donor plants and their regenerants, showed that the level of DNA methylation increased in regenerants by 1.45% compared to the donors. The Methyl-Sensitive Transposon Display (MSTD) based on methylation-sensitive Amplified Fragment Length Polymorphism (metAFLP) approach demonstrated that, depending on the selected elements belonging to the TEs family analyzed, varying levels of sequence variation were evaluated. DNA sequence contexts may have a different impact on SV generated by distinct mobile elements belonged to various TE families. Based on the presented study, some of the selected mobile elements contribute differently to TE-related SV. The surrounding context of the TEs DNA sequence is possibly important here, and the study explained some part of SV related to those contexts.

Soluble and cell wall-bound phenolic acids and ferulic acid dehydrodimers in rye flour and five bread model systems: insight into mechanisms of improved availability.

BACKGROUND: The bread-making process influences bread components, including phenolics that significantly contribute to its antioxidant properties. Five bread model systems made from different rye cultivars were investigated to compare their impact on concentration of ethanol-soluble (free and ester-bound) and insoluble phenolics. RESULTS: Breads produced by a straight dough method without acid addition (A) and three-stage sourdough method with 12 h native starter preparation (C) exhibited the highest, genotype-dependent concentrations of free phenolic acids. Dough acidification by direct acid addition (method B) or by gradual production during prolonged starter fermentation (24 and 48 h, for methods D and E) considerably decreased their level. However, breads B were enriched in soluble ester-bound fraction. Both direct methods, despite substantial differences in dough pH, caused a similar increase in the amount of insoluble ester-bound fraction. The contents of phenolic fractions in rye bread were positively related to activity level of feruloyl esterase and negatively to those of arabinoxylan-hydrolysing enzymes in wholemeal flour. CONCLUSION: The solubility of rye bread phenolics may be enhanced by application of a suitable bread-making procedure with respect to rye cultivar, as the mechanisms of this process are also governed by a response of an individual genotype with specific biochemical profile.

Mode of endosperm and wholemeal arabinoxylans solubilisation during rye breadmaking: genotypic diversity in the level, substitution degree and macromolecular characteristics.

Insight into solubilisation mechanisms of rye arabinoxylans during breadmaking is important for understanding the biochemical processes that affect bread attributes. Purified ethanol precipitated water-extractable arabinoxylans (WE-AX) and residual unextractable counterparts (WU-AX) were isolated from rye flours and resulting breads. While the endosperm flours had lower endoxylanase activities and higher arabinose-to-xylose ratios of WU-AX than those of corresponding wholemeals, there were not any significant differences between them in the mean amounts of WU-AX hydrolysed during breadmaking. Nevertheless, they were highly affected by rye cultivar used for breadmaking. On average, 42% and 36% of WU-AX were recovered in bread WE-AX fraction, causing its 11% and 8% increase, respectively for endosperm and wholemeal breads. Bread WE-AX, however, had lower molecular weights than those of starting flours, implying chains depolymerisation. Degree of AX solubilisation depends mainly on rye genotype used, determining combined effect of enzymatic and acid hydrolyses, associations and fine structure of AX.