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In Triticeae endosperm (e.g. wheat and barley), starch granules have a bimodal size distribution (with A- and B-type granules) whereas in other grasses the endosperm contains starch granules with a unimodal size distribution. Here, we identify the gene, BGC1 (B-GRANULE CONTENT 1), responsible for B-type starch granule content in Aegilops and wheat. Orthologues of this gene are known to influence starch synthesis in diploids such as rice, Arabidopsis, and barley. However, using polyploid Triticeae species, we uncovered a more complex biological role for BGC1 in starch granule initiation: BGC1 represses the initiation of A-granules in early grain development but promotes the initiation of B-granules in mid grain development. We provide evidence that the influence of BGC1 on starch synthesis is dose dependent and show that three very different starch phenotypes are conditioned by the gene dose of BGC1 in polyploid wheat: normal bimodal starch granule morphology; A-granules with few or no B-granules; or polymorphous starch with few normal A- or B-granules. We conclude from this work that BGC1 participates in controlling B-type starch granule initiation in Triticeae endosperm and that its precise effect on granule size and number varies with gene dose and stage of development.

Seasonal fluctuations strongly shape the physiology of long-lived trees by coordinating growth, dormancy, and stress responses. Increasing evidence points to epigenetic mechanisms, particularly DNA methylation, as regulators of these processes, yet their role in long-lived trees across seasons and generations remains poorly understood. We generated single-base resolution maps of cytosine methylation exploring the epigenetic landscape of 180 year-old mature oak (Quercus robur) trees (genetically homogeneous) along spring, summer and autumn, and in their progeny. Genome-wide DNA-methylation revealed a progressive increase in the CHH context (H = A, T or C) from Spring to Summer and Autumn, suggesting epigenetic reprogramming is happening over season. Differentially Methylated Regions (DMRs) were concentrated in promoter regions and terminal inverted repeat (TIR). Differentially methylated transposable elements (TEs) and genes were involved in leaf development and hormonal signalling. By contrast, generational differences (parents versus offspring) were most prominent in CG and CHG contexts and were concentrated in genic regions. Oaks exhibit distinct seasonal and generational DNA methylation signatures, highlighting the plasticity and developmental specificity of epigenetic regulation. These findings provide a genomic foundation for understanding how epigenetic memory contributes to phenology, developmental programming and long-term adaptation in long-lived plants.

The weak acid sorbic acid is a common preservative used in soft drink beverages to control microbial spoilage. Consumers and industry are increasingly transitioning to low-sugar food formulations, but potential impacts of reduced-sugar on preservative efficacy are barely characterised. In this study, we report enhanced sorbic acid resistance of spoilage yeasts in low-glucose conditions. We had anticipated that low glucose may induce respiratory metabolism, previously shown to be targeted by sorbic acid. However, a shift from respiratory to fermentative metabolism was correlated with the sorbic acid resistance in low glucose. Fermentation-deficient yeast species did not show the low-glucose resistance phenotype. Phenotypes observed for certain yeast deletion strains suggested roles for glucose signalling and repression pathways in the sorbic acid resistance at low glucose. This low- glucose induced sorbic acid resistance was alleviated by supplementing yeast cultures with succinic acid, a metabolic intermediate of respiratory metabolism (and a food-safe additive) that promoted respiration. The results indicate that metabolic adaptation of spoilage yeasts promotes sorbic acid resistance at low glucose, providing new insight into potential spoilage, and preservation, of foodstuffs as both food producers and consumers move towards a reduced-sugar landscape.

Previously, we identified a quantitative trait locus on the group 4 chromosomes of Aegilops and bread wheat that controls B-type starch-granule content. Here, we identify a candidate gene by fine-mapping in Aegilops and confirm its function using wheat TILLING mutants. This gene is orthologous to the FLOURY ENDOSPERM 6 (FLO6) gene of rice and barley and the PTST2 gene of Arabidopsis. In Triticeae endosperm, reduction in the gene dose of functional FLO6 alleles results in reduction, or loss, of B-granules. This is due to repression of granule initiation in late-grain development, but has no deleterious impact on the synthesis of A-granules. The complete absence of functional FLO6, however, results in reduced numbers of normal A-type and B-type granules and the production of highly-abnormal granules that vary in size and shape. This polymorphous starch seen in a wheat flo6 triple mutant is similar to that observed in the barley mutant Franubet. Analysis of Franubet (fractured Nubet) starch suggests that the mutant A-granules are not fractured but compound, due to stimulation of granule initiation in plastids during early-grain development. Thus, in different situations in Triticeae, FLO6 either stimulates or represses granule initiation. Footnotes * https://www.ncbi.nlm.nih.gov/genbank/ * https://www.ncbi.nlm.nih.gov/sra/docs/

Mutations at the LYS3 locus in barley have multiple effects on grain development, including an increase in embryo size and a decrease in endosperm starch content. The gene underlying LYS3 was identified by genetic mapping and mutations in this gene were identified in all four barley lys3 alleles. LYS3 encodes a transcription factor called Prolamin Binding Factor (PBF). Its role in controlling embryo size was confirmed using wheat TILLING mutants. To understand how PBF controls embryo development, we studied its spatial and temporal patterns of expression in developing grains. The PBF gene is expressed in both the endosperm and the embryos, but the timing of expression in these organs differs. PBF expression in wild-type embryos precedes the onset of embryo enlargement in lys3 mutants, suggesting that PBF suppresses embryo growth. We predicted the down-stream target genes of PBF in wheat and found them to be involved in a wide range of biological processes, including organ development and starch metabolism. Our work suggests that PBF may influence embryo size and endosperm starch synthesis via separate gene control networks. Footnotes * https://www.ebi.ac.uk

CD14 in apoptosis This study defines a previously unknown specific role for CD14, a molecule that, in conjunction with other receptors, recognizes the lipopolysaccharide (LPS) of bacterial cell wall. CD14 is shown to regulate dendritic cell apoptosis after LPS stimulation via a PLC-γ2–Ca 2+ –NFAT-dependent pathway. This finding significantly advances the knowledge of the molecular events occurring during the initial phases of defence to bacterial infections. Here, CD14 is shown to regulate mouse dendritic cell apoptosis after lipopolysaccharide stimulation via a pathway involving activation of the transcription factor NFAT; an event that is essential for maintaining self-tolerance and preventing autoimmunity. Given the involvement of CD14 in diseases such as sepsis and heart failure, the discovery of signal transduction pathways activated exclusively by CD14 is an important step towards the development of potential new treatments. Toll-like receptors (TLRs) are the best characterized pattern recognition receptors 1 . Individual TLRs recruit diverse combinations of adaptor proteins, triggering signal transduction pathways and leading to the activation of various transcription factors, including nuclear factor κB, activation protein 1 and interferon regulatory factors 2 . Interleukin-2 is one of the molecules produced by mouse dendritic cells after stimulation by different pattern recognition receptor agonists 3 , 4 , 5 , 6 . By analogy with the events after T-cell receptor engagement leading to interleukin-2 production, it is therefore plausible that the stimulation of TLRs on dendritic cells may lead to activation of the Ca 2+ /calcineurin and NFAT (nuclear factor of activated T cells) pathway. Here we show that mouse dendritic cell stimulation with lipopolysaccharide (LPS) induces Src-family kinase and phospholipase Cγ2 activation, influx of extracellular Ca 2+ and calcineurin-dependent nuclear NFAT translocation. The initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. We also show that LPS-induced NFAT activation via CD14 is necessary to cause the apoptotic death of terminally differentiated dendritic cells, an event that is essential for maintaining self-tolerance and preventing autoimmunity 7 , 8 . Consequently, blocking this pathway in vivo causes prolonged dendritic cell survival and an increase in T-cell priming capability. Our findings reveal novel aspects of molecular signalling triggered by LPS in dendritic cells, and identify a new role for CD14: the regulation of the dendritic cell life cycle through NFAT activation. Given the involvement of CD14 in disease, including sepsis and chronic heart failure 9 , 10 , the discovery of signal transduction pathways activated exclusively via CD14 is an important step towards the development of potential treatments involving interference with CD14 functions.