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The improvement of maize double cropping has become increasingly important in recent years. In order to establish breeding programs for sustainable maize production, the goals of the research were (i) to understand the correlations between grain and stover yield and saccharification efficiency, and (ii) to identify QTL and metabolic pathways to design of breeding programs in a double exploitation approach. We carried out a genome-wide association study (GWAS) and a metabolic pathway analysis using a panel of highly diverse maize inbreds. As results, we have obtained that the regulation of energetic and developmental pathways have been pointed out as key pathways related to stover quantity and utilization, while no specific pathways could be identified in relation to grain yield. However, due to the moderate high heritability of yields and their positive correlation a phenotypic selection approach would be adequate for the improvement of both yields, while for saccharification efficiency improvement upcoming genomic selection models are more advisable. Overall, breeding strategies that manage the dual use of maize are viable and will contribute to a more sustainable maize crop in the near future. [ABSTRACT FROM AUTHOR]

Background and Aims Cell wall disassembly occurs naturally in plants by the action of several glycosyl-hydrolases during different developmental processes such as lysigenous and constitutive aerenchyma formation in sugarcane roots. Wall degradation has been reported in aerenchyma development in different species, but little is known about the action of glycosyl-hydrolases in this process. Methods In this work, gene expression, protein levels and enzymatic activity of cell wall hydrolases were assessed. Since aerenchyma formation is constitutive in sugarcane roots, they were assessed in segments corresponding to the first 5 cm from the root tip where aerenchyma develops. Key Results Our results indicate that the wall degradation starts with a partial attack on pectins (by acetyl esterases, endopolygalacturonases, β-galactosidases and α-arabinofuranosidases) followed by the action of β-glucan-/callose-hydrolysing enzymes. At the same time, there are modifications in arabinoxylan (by α-arabinofuranosidases), xyloglucan (by XTH), xyloglucan–cellulose interactions (by expansins) and partial hydrolysis of cellulose. Saccharification revealed that access to the cell wall varies among segments, consistent with an increase in recalcitrance and composite formation during aerenchyma development. Conclusion Our findings corroborate the hypothesis that hydrolases are synchronically synthesized, leading to cell wall modifications that are modulated by the fine structure of cell wall polymers during aerenchyma formation in the cortex of sugarcane roots. [ABSTRACT FROM AUTHOR]

Summary: The recalcitrance of secondary plant cell walls to digestion constrains biomass use for the production of sustainable bioproducts and for animal feed. We screened a population of Brachypodium recombinant inbred lines (RILs) for cell wall digestibility using commercial cellulases and detected a quantitative trait locus (QTL) associated with this trait. Examination of the chromosomal region associated with this QTL revealed a candidate gene that encodes a putative glycosyl transferase family (GT) 43 protein, orthologue of IRX14 in Arabidopsis, and hence predicted to be involved in the biosynthesis of xylan. Arabinoxylans form the major matrix polysaccharides in cell walls of grasses, such as Brachypodium. The parental lines of the RIL population carry alternative nonsynonymous polymorphisms in the BdGT43A gene, which were inherited in the RIL progeny in a manner compatible with a causative role in the variation in straw digestibility. In order to validate the implied role of our candidate gene in affecting straw digestibility, we used RNA interference to lower the expression levels of the BdGT43A gene in Brachypodium. The biomass of the silenced lines showed higher digestibility supporting a causative role of the BdGT43A gene, suggesting that it might form a good target for improving straw digestibility in crops. [ABSTRACT FROM AUTHOR]

Brachypodium distachyon ( Brachypodium) has been proposed as a model for grasses, but there is limited knowledge regarding its lignins and no data on lignin-related mutants. The cinnamyl alcohol dehydrogenase ( CAD) genes involved in lignification are promising targets to improve the cellulose-to-ethanol conversion process. Down-regulation of CAD often induces a reddish coloration of lignified tissues. Based on this observation, we screened a chemically induced population of Brachypodium mutants (Bd21-3 background) for red culm coloration. We identified two mutants ( Bd4179 and Bd7591), with mutations in the Bd CAD1 gene. The mature stems of these mutants displayed reduced CAD activity and lower lignin content. Their lignins were enriched in 8- O-4- and 4- O-5-coupled sinapaldehyde units, as well as resistant inter-unit bonds and free phenolic groups. By contrast, there was no increase in coniferaldehyde end groups. Moreover, the amount of sinapic acid ester-linked to cell walls was measured for the first time in a lignin-related CAD grass mutant. Functional complementation of the Bd4179 mutant with the wild-type Bd CAD1 allele restored the wild-type phenotype and lignification. Saccharification assays revealed that Bd4179 and Bd7591 lines were more susceptible to enzymatic hydrolysis than wild-type plants. Here, we have demonstrated that Bd CAD1 is involved in lignification of Brachypodium. We have shown that a single nucleotide change in Bd CAD1 reduces the lignin level and increases the degree of branching of lignins through incorporation of sinapaldehyde. These changes make saccharification of cells walls pre-treated with alkaline easier without compromising plant growth. [ABSTRACT FROM AUTHOR]

Background In this study, a multi-parent population of barley cultivars was grown in the field for two consecutive years and then straw saccharification (sugar release by enzymes) was subsequently analysed in the laboratory to identify the cultivars with the highest consistent sugar yield. This experiment was used to assess the benefit of accounting for both the multiphase and multi-environment aspects of large-scale phenotyping experiments with field-grown germplasm through sound statistical design and analysis. Results Complementary designs at both the field and laboratory phases of the experiment ensured that non-genetic sources of variation could be separated from the genetic variation of cultivars, which was the main target of the study. The field phase included biological replication and plot randomisation. The laboratory phase employed re-randomisation and technical replication of samples within a batch, with a subset of cultivars chosen as duplicates that were randomly allocated across batches. The resulting data was analysed using a linear mixed model that incorporated field and laboratory variation and a cultivar by trial interaction, and ensured that the cultivar means were more accurately represented than if the non-genetic variation was ignored. The heritability detected was more than doubled in each year of the trial by accounting for the non-genetic variation in the analysis, clearly showing the benefit of this design and approach. Conclusions The importance of accounting for both field and laboratory variation, as well as the cultivar by trial interaction, by fitting a single statistical model (multi-environment trial, MET, model), was evidenced by the changes in list of the top 40 cultivars showing the highest sugar yields. Failure to account for this interaction resulted in only eight cultivars that were consistently in the top 40 in different years. The correspondence between the rankings of cultivars was much higher at 25 in the MET model. This approach is suited to any multiphase and multi-environment population-based genetic experiment. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) from the Algerian Sahara was adapted to arid conditions and has been used for food and feed. The objective of this work was to assess the potential value of Saharan maize for saccharification and nutritive value under drought conditions. Eighteen maize populations from the Algerian Sahara were evaluated under drought and control conditions and representative samples of those populations were taken for nutrients and saccharification analyses. The evaluation of saccharification was made in one Spanish trial under drought and control conditions. Differences among Algerian populations for nutritive value were significant for starch and ash, but not for lipids and proteins. Drought-reduced saccharification yield and differences among populations were significant for saccharification potential under drought conditions, and for saccharification yield under both drought and control conditions. The Algerian populations PI527465 and PI542689 had high grain starch and low ash, PI527469 and PI527474 had a balanced nutritional value, and PI527475 and PI542683 had low grain starch and moderately high ash. Besides high nutritional value, the drought-tolerant population PI542683 had high saccharification under drought conditions. Most agronomic traits had no significant effects on saccharification, and some grain nutrients affected saccharification and agronomic performance. Therefore, improving the nutritive value of grain and saccharification of stover, while maintaining agronomic performance, could be feasible, attending to the weak interactions between them. [ABSTRACT FROM AUTHOR]

Cassava (Manihot esculenta Crantz) is a key crop for starch and biofuels production. This study focuses on the polysaccharide composition and saccharification efficiency in cassava pulp through genome-wide association studies (GWAS), targeting the improvement of root characteristics for industrial use. We analyzed 135 partially inbred lines population, performing monosaccharide composition and saccharification analyses to reveal substantial variability in storage root biomass. Among 33 traits examined, 128 significant SNPs were associated with 23 biomass traits, highlighting a complex genetic architecture. Saccharification potential varied from 39 to 95 nmol Glu mg−1 h−1, with high broad-sense heritability for saccharification and several monosaccharide traits, indicating a strong genetic control. Our findings revealed that cassava pulp comprises similar proportions of pectin, hemicellulose, and cellulose in all genotypes. Correlation analysis showed significant associations between cellulose content and saccharification, suggesting that enhancing these traits can improve bioconversion efficiency. Negative correlations with glucose and glucuronic acid in hemicellulose and pectin fractions imply these components may inhibit saccharification. We identified 118 candidate genes associated with 21 traits, with many involved in stress responses affecting cell wall composition. This study verified 12 key candidate genes through sequence and expression analysis, including MANES_07G081200 , a YTH domain-containing protein associated with saccharification. Several stress-response genes, such as MANES_04G118600 and MANES_09G174600 , were linked to monosaccharide traits, suggesting that adaptive stress pathways influence biomass characteristics. This study provides insights into the genetic determinants of cassava pulp's saccharification and polysaccharide composition, aiding breeding efforts to develop cassava varieties optimized for industrial applications. • GWAS identifies 128 significant SNPs linked to 23 cassava biomass traits based on cassava pulp. • High heritability found for saccharification and several monosaccharide traits. • Negative impact of glucose and glucuronic acid on saccharification of cassava pulp. • 118 candidate genes identified, many involved in stress responses affecting cell wall composition. [ABSTRACT FROM AUTHOR]

Valorizing rice straw could mitigate the detrimental health and environmental consequences of disposal through field burning. An essential step for achieving this is reducing straw recalcitrance to digestion by either enzymes or animals to facilitate uses as fertilizer, animal feed, or conversion into fuels and chemicals. In the present work, we developed and characterized a Philippine rice diversity panel to explore the chemical basis of biomass recalcitrance. We used high throughput phenotyping of straw samples from the panel to identify chemical compounds that confer recalcitrance. We determined the saccharification potential, silica, ferulic, and p-coumaric acid content in each rice accession, as well as the chemical fingerprint of biomass composition using pyrolysis followed by GC/MS. Multivariate analysis of the phenotypic data allowed us to characterize the relationship between biomass components and straw saccharification establishing that Si, ferulic acid and coumaric acid are inversely correlated with saccharification. PCA analysis showed that pyrolysis products derived from lignin constitute the largest proportion of compounds inversely correlated with saccharification. • A rice association panel was characterized for straw quality. • Pyr-GC/MS fingerprinting of straw shows the compositional diversity in the panel. • Silica, coumaric acid and ferulic acid are inversely correlated to saccharification. • We identified pyrolysis peaks associated with saccharification potential. [ABSTRACT FROM AUTHOR]