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Genomic and functional characterization of sugar transporters reveals potential roles in sugar accumulation in a modern sugarcane cultivar.

Sugarcane (Saccharum spp.) is a globally important sugar crop whose productivity depends on efficient sugar transport from source to sink organs. However, systematic identification and functional characterization of sugar transporters (STs) in sugarcane cultivars remain limited. Here, we identified 190 non-redundant ST genes in sugarcane cultivar Guitang 42 (GT42) and phylogenetically classified them into nine groups within the Monosaccharide Transporter (MST), Sucrose Transporter (SUT), and Sugars Will Eventually be Exported Transporters (SWEET) families. Comparative evolutionary analysis revealed significant lineage-specific expansions in the PMT, STP subfamilies, and SWEET families compared to diploid and wild relatives, likely driven by polyploidization and intensive selection for sugar yield. Transcriptomic profiling across tissues and internode elongation stages demonstrated marked tissue-specific and developmental expression patterns. Yeast complementation assays confirmed the transport activity of candidate MSTs, SUTs and SWEETs, with confocal microscopy verifying their distinct subcellular localization at the plasma membrane, tonoplast, or endoplasmic reticulum. Furthermore, transient overexpression of several candidate transporters (ScSWEET4-T2, ScSWEET15, and ScTST4-T1) in Nicotiana benthamiana modulated soluble sugar accumulation, and their expression in sugarcane protoplasts activated key sugar-responsive marker genes (ScGPT2 and ScWIP4). Together, our study establishes a systematic genomic framework and identifies candidate functional transporters that govern sugar partitioning and storage, providing valuable genetic targets for molecular breeding and quality enhancement in sugarcane.

Functional characterization

Phosphorylation and ubiquitination coordinate homeostasis of a tomato transporter responsible for fruit sugar accumulation.

Sugar transport mediated by different transporters is essential for maintaining sugar homeostasis in plants. Here, we report that phosphorylation and ubiquitination coordinate the homeostasis of a tomato (Solanum lycopersicum) sugar transporter SlSWEET16, revealing a new aspect of plant sugar homeostasis. SlSWEET16 is localized to plasma membrane and functions as a mono- and disaccharide transporter. SlSWEET16 mediates cellular sugar efflux, and CRISPR/Cas9-mediated knockout of SlSWEET16 leads to increased fruit sugar accumulation. Strikingly, the C-terminus of SlSWEET16 is subjected to both phosphorylation and ubiquitination. Two protein kinases including SlSnRK2.3 and SlSnRK2.4 associate with the C-terminus of SlSWEET16, resulting into an increase in the stability of SlSWEET16. Meanwhile, the C-terminus of SlSWEET16 also interacts with an E3 ubiquitin ligase SlTT3.1L2, which decreases the stability of SlSWEET16. SlSnRK2.3 and SlSnRK2.4 inhibit fruit sugar accumulation, whereas SlTT3.1L2 promotes it. Mutations of phosphorylated or ubiquitinated residues in SlSWEET16's C-terminus further corroborate the contribution of phosphorylation and ubiquitination to the stability of SlSWEET16 and fruit sugar accumulation. Our results reveal a multiple-protein regulatory module that integrates different post-translational modifications to control transporter-mediated fruit sugar accumulation.

Solanum lycopersicum

Metabolomics-based authentication of acacia honey against C3 and C4 sugar adulteration.

Acacia (Robinia pseudoacacia) honey is frequently adulterated with low-cost alternatives via direct syrup addition or in-hive sugar feeding. We focused on sugar-feeding adulterants, which is difficult to distinguish from nectar-based honey. Stable carbon isotope ratio analysis (SCIRA) is an established method for assessing honey authentication; however, its applicability is limited to detecting C4 plant-derived sugar adulteration. Therefore, we developed a metabolomics-based multi-marker strategy to discriminate acacia honey from beet-sugar (C3)- and cane-sugar (C4)-fed honey. Thirteen metabolites were prioritized using combined multivariate and univariate criteria. Subsequently, 1716 panels of seven-marker (13C7) were evaluated for discrimination performance. 291 panels achieved 100% accuracy in an independent validation set. In blending scenarios, acacia honeys spiked with 20% beet-sugar-fed honey and 20% cane-sugar-fed honey were successfully identified, outperforming SCIRA (60%) and beet-sugar marker 3-methoxytyramine (3-MT) (30%). These findings establish metabolomic panels as a robust marker for acacia honey authentication, extending beyond current reference methods.

Acacia

Advances in Cytoplasmic Male Sterility in Sugar Beet from Mitochondrial Genome Structural Dynamics and Nuclear-Cytoplasmic Coordination.

Sugar beet (Beta vulgaris L.) is a globally important sugar crop whose hybrid breeding system relies heavily on cytoplasmic male sterility (CMS) lines. Recent advances in sugar beet genomics, particularly the release of high-quality reference genomes and the characterization of organellar genomes, have provided a foundation for elucidating the molecular genetic mechanisms of CMS. Furthermore, innovations in gene editing technologies are enabling transformative functional studies in this field. The precise targeting of CMS-associated mitochondrial genes and nuclear restorer-of-fertility genes not only allows for direct investigation of theoretical models governing fertility regulation through nuclear-cytoplasmic interactions but also holds promise for the targeted development of sterile and restorer lines. This review systematically summarizes progresses in sugar beet genomics, the development of gene editing tools, and the current understanding of the molecular genetics of CMS and fertility restoration in sugar beet. Although challenges remain-such as efficient delivery of editing tools into mitochondria and coordinated editing of multiple genes-the integration of genomic and gene editing technologies is expected to accelerate multi-omics-guided dissection of CMS mechanisms. These advances will facilitate the precise design of high-yield, high-sugar, and stress-resistant sugar beet hybrids, thereby providing core scientific and technological support for the sustainable development of the global sugar industry.

Beta vulgaris

Versatile sugar and valerate metabolic pathways in Paraburkholderia xenovorans LB400 enable tailored poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production.

Poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) polymers are accumulated by diverse prokaryotes. Their distinct monomer compositions enable their use as tailored bioplastics. The aims were to characterize the poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis by Paraburkholderia xenovorans LB400 using different sugars and valerate, and to gain genome-oriented insights into polyhydroxyalkanoate production. d-Glucose, d-mannitol, d-gluconate, and d-xylose were evaluated as sole carbon sources or supplemented with valerate. Polyhydroxyalkanoates synthesized by strain LB400 were characterized through GC-MS, GC-FID, FTIR, and 1H and 13C-NMR. P. xenovorans LB400 reached 1.00-1.39 g L-1 of dry cell weight (DCW) with a P(3HB) content of 21-43% w w-1 when grown on different sugars. The addition of valerate to the sugar-grown LB400 cultures yielded a DCW of 1.79 to 2.29 g L-1 and a P(3HB-co-3HV) content of 50.0‒51.2% w w-1, with varying 3HV compositions (28‒43 mol%). The highest 3HV incorporation was observed with d-xylose and valerate. Genomic analyses of strain LB400 revealed key elements of sugar metabolism influencing growth, polymer accumulation, and monomer composition. LB400 genome encodes the PhaJ-like R-specific hydratase and FadJ epimerase, which are potentially useful for modulating copolymer composition. PHA production under bioreactor conditions was evaluated. In a bioreactor fed with d-glucose, LB400 achieved a P(3HB) concentration of 2.2 g L-1. These findings highlight the metabolic versatility of P. xenovorans LB400 in utilizing diverse sugars to produce either P(3HB) or tailor-made P(3HB-co-3HV), supporting the development of bioplastics for specific applications. KEY POINTS: • Strain LB400 produced P(3HB-co-3HV) from various sugars and valerate. • Sugar type drives LB400 PHA copolymer synthesis and composition. • Strain LB400 PHA production was scaled up to a bioreactor.

Polyesters

Transcriptional landscape and dynamics involved in sugar and acid accumulation during apple fruit development.

In fleshy fruit, sugars and acids are central components of fruit flavor and quality. To date, the mechanisms underlying transcriptional regulation of sugar and acid during fruit development remain largely unknown. Here, we combined ATAC-seq with RNA-seq to investigate the genome-wide chromatin accessibility and to identify putative transcription factors related to sugar and acid accumulation during apple (Malus domestica) fruit development. By integrating the differentially accessible regions and differentially expressed genes, we generated a global data set of promoter-accessibility and expression-increased genes. Using this strategy, we constructed a transcriptional regulatory network enabling screening for key transcription factors and target genes involved in sugar and acid accumulation. Among these transcription factors, 5 fruit-specific DNA binding with one finger genes were selected to confirm their regulatory effects, and our results showed that they could affect sugar or acid concentration by regulating the expression of sugar or acid metabolism-related genes in apple fruits. Our transcriptional regulatory network provides a suitable platform to identify candidate genes that control sugar and acid accumulation. Meanwhile, our data set will aid in analyzing other characteristics of apple fruit that have not been illuminated previously. Overall, these findings support a better understanding of the regulatory dynamics during apple fruit development and lay a foundation for quality improvement of apple.

Malus

Over expression of modified Isomaltulose Synthase Gene II (ImSyGII) under single and double promoters drive unprecedented sugar contents in sugarcane.

Sugarcane has been grown all around the world to meet sugar demands for industrial sector. The current sugar recovery percentage in sugarcane cultivars is dismally low which demands scientific efforts for improvements. Multiple approaches were adopted to enhance sugar contents in commercial sugarcane plants in contrast to conventional plant breeding methods. The exploitation of biotechnological methods and exploration of isomaltulose synthetic genes presented a promising solution to increase the existing low level of sugar recovery percentage in Saccharum officinarum L. Isomaltulose synthase gene II was employed and integrated into plant expression vector driven under the leaf and stem specific promoters terminated by nopaline synthase gene in a cloning strategy shown in the present study. Three gene constructs were developed in various combinations driven under promoters Zea mays ubiquitin and Cestrum Yellow Leaf Curl virus in the single and double combined stacked system. The transformation was executed in multiple formats with single transformed events, double promoter transformation events and triple construct stacked promoters in sugarcane induced calli via the particle gene gun. The transformation of ImSyGII in sugarcane genotype HSF-240 was confirmed by molecular gene analysis while expression quantification was determined through Real Time PCR. Furthermore, HPLC was also done to harvest the increased amounts of Isomaltulose in transgenic sugarcane juice. The present work upheld the enhanced ImSyGII expression in leaves owing to the exploitation of ubiquitin, while the Cestrum Yellow Leaf Curl virus promoter enhanced gene expression in sugarcane stems. The employment of three gene constructs collectively produced elite sugar lines producing more than 78% enhancements in whole sugar recovery percentage. The mature internode proved highly efficient and receptive regarding the production of isomaltulose. Quantifications and sugar contents evaluations upheld an increased Brix ratio of transgenic sugarcane lines than control lines.

Saccharum

Development and validation of whole-genome SSR markers in sugar beet (Beta vulgaris L.).

Sugar beet (Beta vulgaris L.) is an important sugar and cash crop worldwide. To systematically characterize SSR (Simple Sequence Repeat) loci across sugar beet chromosomes and enable the precise identification of germplasm resources, this study conducted a genome-wide scan for SSR loci, analyzed their distribution patterns, and determined their genotypes using resequencing data from 123 sugar beet varieties. The results revealed an abundance of SSR loci in the sugar beet genome, with a total of 135, 379 identified, from which 135, 344 pairs of SSR primers were designed (135, 344 primer pairs successfully designed; 35 loci failed to meet design criteria). Specifically, 31, 748 primer pairs were designed based on SSRs located in unassigned scaffolds, and 103, 596 primer pairs from SSRs assigned to the nine chromosomes. Through bioinformatic analysis, we identified 28, 768 SSR primers located in multi-copy genes with PIC (Polymorphism Information Content) ≥ 0.5, and 2, 326 SSR markers located in single-copy genes residing in various genic regions (among which 543 had PIC ≥ 0.5, with the highest reaching 0.776). PCR (Polymerase Chain Reaction) validation confirmed 20 robust and polymorphic markers producing clear and reproducible bands. Among them, 10 SSR primers located in multi-copy genes exhibited three or more polymorphic types, and 10 markers located in single-copy genes displayed 2-3 polymorphic types. The most polymorphic marker, YCD-4-2, detected 11 polymorphic types across 48 varieties. Furthermore, to explore markers with potential functional significance, we annotated the genes harboring SSR markers located in single-copy genes. The results showed that 1, 264 SSRs located in single-copy genes were localized to 967 genes, which are significantly enriched in pathways related to carbohydrate metabolism, stress responses, and plant-pathogen interactions. The 20 validated markers and the 2, 326 SSRs located in single-copy genes provided in this study can be directly applied to fingerprinting of sugar beet varieties, seed purity testing, and marker-assisted selection, thus representing a practical resource for molecular breeding.

genome-wide

Cultivar-Specific Differences in C6 and C7 Sugar Metabolism During Avocado Ripening: Comparative Insights from Bacon, Fuerte, and Hass.

Avocado is a unique fruit in which of seven-carbon (C7) sugars (notably D-mannoheptulose and perseitol) dominate the carbohydrate profile at harvest. Despite growing interest in sugar-mediated ripening processes, limited comparative data exist across cultivars. This work characterises the dynamic changes in non-structural carbohydrates in the mesotecarp of three commercially relevant avocado varieties-Bacon, Fuerte, and Hass-across four defined ripening stages, from unripe to overripe, with five biological replicates per stage. Using a validated hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) method, we quantified five key sugars and assessed their evolution through ripening. Concentrations varied among the studied samples within the following ranges: D-mannoheptulose, 0.4-49 mg/g dry weight (DW); perseitol, 0.5-23 mg/g DW; glucose, 0.8-5.3 mg/g DW; fructose, 0.6-4.5 mg/g DW; and sucrose, 0.5-3.4 mg/g DW. C7 sugar levels consistently declined, while C6 sugars increased-primarily between the intermediate and ready-to-eat stages-with distinct cultivar-specific patterns. Bacon maintained elevated C7 concentrations for a longer period; Fuerte exhibited a rapid transition from C7 to C6 sugars; and Hass displayed a more gradual and balanced shift. Multivariate analysis (partial least squares discriminant analysis, PLS-DA) effectively discriminated between cultivars at each ripening stage, confirming cultivar-specific metabolic signatures. These findings offer new insights into avocado carbohydrate metabolism, emphasising variety-dependent pathways that could inform breeding strategies, optimise postharvest ripening protocols, and support the nutritional characterisation of different avocado cultivars.

Persea americana

Sugar rationing during the first 1000 days and early onset cancer: a natural experiment.

BACKGROUND: The "first 1000 days" of life is a critical window for metabolic programming, while the long-term oncological consequences of nutritional exposures during this period remain understudied. OBJECTIVES: We aimed to evaluate whether restricted sugar intake in utero and during early childhood reduces risk of early onset cancer diagnosis and mortality in adulthood, utilizing a natural experiment. METHODS: We analyzed 63,819 United Kingdom Biobank participants born between October 1951 and March 1956, spanning the end of United Kingdom sugar rationing (September 1953). Leveraging a quasi-experimental birth cohort design, we compared participants exposed to sugar rationing in utero and during infancy with those unexposed. Early onset cancer incidence (&#x2264;50 y) and mortality were ascertained via integrated national Cancer Registry and hospital inpatient records. Multivariable Cox proportional hazards models (including Gompertz distribution) were used to estimate hazard ratios (HRs), with exploratory site-specific analyses. RESULTS: Among 63,819 participants (56.3% female), 40,397 were exposed to rationing and 23,422 were unexposed. Early life sugar restriction significantly reduced early onset cancer risk (HR: 0.66; 95% confidence interval: 0.53, 0.81; P < 0.001). A dose-response relationship was observed, with peak protection in individuals exposed for &#x2264;24 mo postnatally. This protection was observed systemically across solid tumors, independent of specific cancer sites. Specificity was corroborated by null associations with negative controls (herpes zoster and cataract). No significant difference was found for cancer-specific mortality. CONCLUSIONS: Restricting sugar intake during the first 1000 days is associated with a reduced risk of early onset cancer, extending the disease-free lifespan. The divergence between reduced incidence and unchanged mortality suggests early life metabolic environments primarily influence tumor latency rather than biological aggressiveness. These findings highlight the potential long-term public health implications of early life dietary guidelines against the rising burden of early onset cancer.

Humans

Early life sugar rationing and ageing related diseases, biological ageing and mortality.

Early-life nutrition may influence lifelong ageing, yet human evidence is scarce. Using Britain's postwar sugar rationing as a natural experiment, we examine its long-term effects in 64,809 United Kingdom Biobank participants. Exposure to sugar rationing during the first 1,000 days of life is associated with a 9% lower incidence of hallmark-related disease, with a hazard ratio of 0.91 and a 95% confidence interval of 0.88-0.94, and a 19% lower risk of all-cause mortality, with a hazard ratio of 0.81 and a 95% confidence interval of 0.69-0.93. Mediation analysis indicates that the survival association is statistically mediated, by approximately 60%, through differences in incident hallmark-related disease. Rationed individuals show 1.0-1.2-year younger biological ages across multiple clocks and lower organ ages, particularly in the lung, heart, and liver. Proteomic profiling identifies 47 altered proteins, with enrichment of adenosine monophosphate-activated protein kinase and longevity pathways and suppression of mechanistic target of rapamycin signaling. These findings are consistent with international recommendations to limit free or added sugars from the World Health Organization, United States Dietary Guidelines, and American Heart Association, and may inform policy discussions related to sugar taxation and infant food and marketing policies under the United Nations 2030 Agenda.

Humans

Trends in the Prevalence of Foods High in Saturated Fats, Sodium, and Added Sugars among U.S. adults, NHANES 2007-2018.

BACKGROUND: Foods and beverages high in saturated fats, sodium, and added sugars (HFSS) are often ultra-processed and linked to poor health outcomes, but few studies have investigated their intake. OBJECTIVE: To describe the trends in the intake of HFSS foods and beverages between 2007 and 2018 in a nationally representative sample of U.S. adults, by sociodemographic characteristics and What We Eat in America food groups. DESIGN: This is a secondary, cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. PARTICIPANTS/SETTING: The final sample included 27,984 adults 19 years of age or older from NHANES with at least one complete dietary recall. MAIN OUTCOME MEASURES: The primary outcomes are the percentage of total energy intake from foods classified as HFSS according to the Pan American Health Organization (PAHO) Nutrient Profile Model. STATISTICAL ANALYSES PERFORMED: To estimate the percentage of energy intake from foods and beverages HFSS, linear regression models with interaction terms between cycles and covariates were used. RESULTS: The overall intake of foods and beverages HFSS did not change, representing over 60% of the total energy intake between 2007-2010 and 2015-2018. The intake of foods and beverages high in sodium increased by 2.0 percentage points (95% CI: 0.5, 3.5) and 3.5 percentage points (95% CI: 1.1, 5.8), respectively. The intake of foods and beverages high in saturated fats increased by 6.1 percentage points (95% CI: 4.5, 7.6) and 6.1 percentage points (95% CI: 3.9, 8.2), respectively. The intake of foods and beverages high in added sugars did not change. CONCLUSION: In the U.S., intake of HFSS foods and beverages is high. Future research should focus on whether public health interventions and policies might reduce the intake of foods high in nutrients of concern.

Added sugars

Ribose Sugar Alters Conformational Sampling of G&#x22c5;T Mismatched Duplex DNA.

Polymerases erroneously incorporate Guanine-Thymine (dG&#x22c5;dT) mismatches in genomic DNA that further evades repair by transient sampling of tautomeric/ionic states compromising fidelity of repairing dG&#x22c5;dT mismatches. In conjunction, significant frequency of ribose (mis)incorporation in duplex DNA permits for misincorporated-mismatch in the genome. Ribose incorporated G (rG) mismatched with T (rG&#x22c5;dT) is the most stable across all misincorporated-mismatch calling into question the conformational consequences of the ribose sugar in addition to the mismatch. In this work, the effects of single rG&#x22c5;dT is investigated within a dodecamer DNA duplex employing solution-state NMR spectroscopy, partial anisotropic measurements in conjunction with molecular dynamics simulations to evaluate the impact on base pairs and the overall duplex structure. It is observed that rG&#x22c5;dT pairs exhibit enhanced flexibility in both base-pair and sugar dynamics compared to dG&#x22c5;dT, and the perturbations are enhanced in comparison to a ribose incorporated adenine-thymine (rA-dT) pair. The structural perturbations compared between rG&#x22c5;dT and dG&#x22c5;dT provides clues on plausible recognition modes of ribonucleotide excision repair (RER) pathway that looks for misincorporated ribose and mismatch repair (MMR) enzymes that scout for a mismatch.

Ribose

Sulfonamide-induced DNA hypomethylation disturbed sugar metabolism in rice (Oryza sativa L.).

DNA methylation is well-accepted as a bridge to unravel the complex interplay between genome and environmental exposures, and its alteration regulated the cellular metabolic responses towards pollutants. However, the mechanism underlying site-specific aberrant DNA methylation and metabolic disorders under pollutant stresses remained elusive. Herein, the multilevel omics interferences of sulfonamides (i.e., sulfadiazine and sulfamerazine), a group of antibiotics pervasive in farmland soils, towards rice in 14&#xa0;days of 1&#xa0;mg/L hydroponic exposure were systematically evaluated. Metabolome and transcriptome analyses showed that 57.1-71.4&#xa0;% of mono- and disaccharides were accumulated, and the differentially expressed genes were involved in the promotion of sugar hydrolysis, as well as the detoxification of sulfonamides. Most differentially methylated regions (DMRs) were hypomethylated ones (accounting for 87-95&#xa0;%), and 92&#xa0;% of which were located in the CHH context (H&#xa0;=&#xa0;A, C, or T base). KEGG enrichment analysis revealed that CHH-DMRs in the promoter regions were enriched in sugar metabolism. To reveal the significant hypomethylation of CHH, multi-spectroscopic and thermodynamic approaches, combined with molecular simulation were conducted to investigate the molecular interaction between sulfonamides and DNA in different sequence contexts, and the result demonstrated that sulfonamides would insert into the minor grooves of DNA, and exhibited a stronger affinity with the CHH contexts of DNA compared to CG or CHG contexts. Computational modeling of DNA 3D structures further confirmed that the binding led to a pitch increase of 0.1&#xa0;&#xc5; and a 3.8&#xb0; decrease in the twist angle of DNA in the CHH context. This specific interaction and the downregulation of methyltransferase CMT2 (log2FC&#xa0;=&#xa0;-4.04) inhibited the DNA methylation. These results indicated that DNA methylation-based assessment was useful for metabolic toxicity prediction and health risk assessment.

DNA Methylation

Tonoplast sucrose transporter SUT4-dependent sugar partitioning modulates phenological transitions and reproductive success in poplar.

Climate uncertainty is intensifying the need for greater plasticity in carbohydrate reserve utilization to support winter survival and spring growth in woody perennials. In poplar, the single-copy SUT4, which encodes a tonoplast-localized sucrose transporter, and the SUT5/SUT6 genome duplicates, which encode plasma membrane-localized transporters, are expressed year-round, with SUT4 showing the highest expression during cool seasons. Given its role in vacuolar sucrose efflux and winter-predominant expression, SUT4 may play a key role in modulating seasonal carbohydrate dynamics. While SUT4-knockdown and knockout effects have been studied under greenhouse conditions, their impact under field conditions remains unexplored. Here, we report a field-based study comparing CRISPR knockout mutants of winter-expressed SUT4 and SUT5/SUT6 in Populus tremula&#x2009;&#xd7;&#x2009;alba. We show that sut4, but not sut5/6, mutants exhibited earlier autumn leaf senescence, delayed spring bud flush, reduced stem growth, and altered sugar partitioning in winter xylem and bark relative to controls. After 2&#x2009;years in the field, all genotypes flowered before leaf flush in early spring; however, sut4 mutants produced sterile ovules despite developing normal-looking catkins. Metabolic profiling revealed disrupted sucrose and raffinose dynamics in elongating sut4 catkins. This was accompanied by transcriptomic signatures of elevated stress and downregulation of proanthocyanidin biosynthesis and circadian clock genes. These findings highlight the critical role of SUT4 in coordinating sugar allocation, stress responses, and seasonal development in poplar.

Populus

Hide and seek: de novo identification in sugar beet reveals impact of non-autonomous LTR retrotransposons.

Plant genomes are filled with retrotransposons and their derivatives, constantly undergoing sequence diversification and structural rearrangement. Among them, short, non-autonomous retrotransposons lack full coding capacity and often form subfamilies. As a result, non-autonomous retrotransposons are incompletely identified in most to all genome assemblies.Here, we capitalize on our comprehensive understanding of the transposable element (TE) landscape in sugar beet (Beta vulgaris) to assess the extent of the blind spot for non-autonomous long terminal repeat (LTR) retrotransposons. This use case serves to answer if all of these sequences are derivatives of easier-to-identify full-length elements or if there is more variability that is currently overlooked.For this we applied a semi-automated structural discovery workflow followed by in-depth manual verification to characterize non-autonomous LTR retrotransposons in sugar beet. We retrieve more than 100 non-autonomous LTR retrotransposon families that lack complete autonomous coding capacity, including canonical terminal-repeat retrotransposons in miniature (TRIMs), elongated non-coding derivatives and families retaining fragmented coding remnants. The identified families span a broad range, including elements exceeding 15,000&#xa0;bp in length and display evidence for reshuffling and modular evolution. Only a subset of families could be confidently linked to autonomous retrotransposons, showing sequence diversification within the non-autonomous LTR retrotransposon fraction beyond the autonomous genomic templates.We highlight that a large fraction of non-autonomous LTR retrotransposons is incompletely recovered with the current TE identification workflows, even if the output is well-curated and condensed into TE libraries and suggest procedures to remedy this gap. This study gives a genome-wide view into the non-autonomous LTR retrotransposon landscape of a single plant genome and highlights the importance of structure-based approaches for their identification and classification.

LTR retrotransposons

Sugar kelp (Saccharina latissima) population genetics map onto geographic distance and oceanographic features across coastal Maine.

Sugar kelp (Saccharina latissima; order Laminariales) plays a vital role in kelp forest ecosystems, as well as an expanding kelp aquaculture industry, in the Gulf of Maine, United States. However, ocean warming is eroding the resilience of Maine's kelp forests and may be compromising their local genetic diversity, with impacts on population structure and gene flow. Here, we used genome-wide single nucleotide polymorphism (SNP) data to assess the genetic diversity, structure, and connectivity of S. latissima populations at 11 outer coastal sites spanning the historical range of kelp forests in Maine. Our analyses identified moderate genetic diversity and limited inbreeding within sites (average heterozygosity: 0.27). Further, they revealed that three clusters comprising four genetically distinct populations exist across the study region. Population structure was strongly associated with geographic distance and oceanographic features, as supported by principal coordinate analysis, FST calculations, Bayesian clustering, and spore dispersal modeling. Lastly, our outlier analysis identified genes potentially under selection. Thus, our findings highlight distinct, genetically unique kelp populations along Maine's coast and emphasize the need for regional management strategies that support both ecosystem resilience and sustainable aquaculture under climate change.

Gulf of Maine

Sugar-sweetened beverage consumption and incident depression: an exploratory multi-omics analysis of candidate biological mediators.

BACKGROUND: Depression is a leading cause of mental and physical disability globally, with its onset and progression influenced by a complex interplay of dietary, psychological, and biological factors. Recent research suggests a link between sugar-sweetened beverage (SSB) consumption and depression risk, although the potential biological pathways underlying this association remain poorly understood. METHODS: This study utilized data from 192,045 participants in the UK Biobank to examine the prospective association between SSB consumption and incident depression using Cox proportional hazards models. SSBs were defined as the sum of five beverage categories assessed via the Oxford WebQ 24-hour dietary recall. Directional consistency of the association was further examined across three external supporting datasets encompassing diverse populations: NHANES, YRBSS, and the Lianyungang Municipal School Health and Risk Factor Surveillance Study Dataset. We further investigated whether proteins, metabolites, inflammatory markers, and brain imaging phenotypes may serve as candidate mediators statistically consistent with mediation of the SSB-depression association. RESULTS: High SSB consumption was associated with an 18% higher risk of incident depression compared with non-consumers (HR&#x2009;=&#x2009;1.18; 95% CI: 1.11-1.25), with consistent directional associations observed across external supporting datasets. A plasma proteomic signature comprising 229 proteins was constructed using elastic net regularization and was associated with an increased risk of incident depression. Exploratory mediation analyses identified 72 proteins, 36 metabolites, and 5 inflammatory markers as candidate mediators, with IL1RN showing the strongest protein-level candidate mediating effect (9.6%), and Unsaturation and neutrophil count showing the strongest metabolite- and inflammatory marker-level effects, respectively. CONCLUSIONS: This study provides preliminary evidence that proteins, metabolites, and inflammatory markers may serve as candidate mediators statistically consistent with mediation of the association between SSB consumption and incident depression. These findings are exploratory and hypothesis-generating, and future experimental studies are needed to validate these candidate pathways and assess their potential as targets for dietary interventions in depression prevention.

Humans