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Background This study evaluated the effects of different temperatures (5 °C, 10 °C, 15 °C, and 25 °C) on the fermentation characteristics, microbial communities, and free amino acids (FAAs) dynamics of oat ( Avena sativa ) silage. Results Fermentation was significantly inhibited at 5 °C, characterized by a slower pH decline, lower lactic acid production, and a reduced lactic acid to acetic acid (LA/AA) ratio. Under low-temperature conditions, microbial diversity was higher, with Pseudomonas , Enterobacter , and Proteobacteria becoming more abundant. At low temperatures, several free amino acids (FAAs), particularly lysine, histidine, and arginine, accumulated. Correlation analysis revealed that Enterobacter and Pseudomonas were positively correlated with many FAAs, suggesting their involvement in protein degradation and amino acid transformation under low-temperature conditions. Conclusions These findings contribute to a deeper understanding of the microbial and biochemical mechanisms of low-temperature silage fermentation and provide a theoretical basis and strategic support for optimizing silage quality in cold regions. Graphical abstract

Background Leaf color mutants serve as valuable models for investigating chloroplast development, chlorophyll metabolism, and photosynthetic regulation. However, research on oat mutagenesis remains limited, and the physiological and molecular effects of leaf color mutations in oats are not fully understood. The zebra-striped oat mutant, derived from the wild-type Everleaf via sodium azide (SA) mutagenesis, exhibits distinct white leaf stripes, impaired pigment accumulation, and reduced photosynthetic efficiency. This mutant serves as a model to investigate the underlying molecular mechanisms of pigment biosynthesis and photosynthetic efficiency, offering valuable resources for oat molecular breeding and the development of specialty varieties. Results The zebra-striped mutant displays a significant reduction in most pigments, particularly carotenoids (43.80% reduction), while chlorophyll b remains largely unaffected. Photosynthetic efficiency and chlorophyll fluorescence parameters are substantially impaired, resulting in stunted growth and poor agronomic performance, with a 16.95% decrease in main panicle seed number and a 26.59% reduction in seed weight of the main panicle. Transcriptome analysis revealed 1,958 DEGs between the mutant and wild-type, including 571 up-regulated and 1,387 down-regulated genes. These DEGs were enriched in GO terms related to chlorophyll biosynthesis, chloroplast function, and carbohydrate binding. KEGG pathway analysis implicated these genes in chlorophyll and carotenoid biosynthesis (e.g., CHLD, POR, ZDS, BCH), photosynthesis, and photosynthetic carbon fixation. Additionally, 36 DEGs in the starch and sucrose metabolic pathways were down-regulated, leading to inhibited starch and sucrose metabolism. qRT-PCR validated reduced expression of key genes (CHLD, POR, LHCB1), confirming their role in the mutant phenotype. Conclusions The zebra-striped phenotype results from disruptions in pigment synthesis, metabolic pathways, and photosynthetic carbon fixation, leading to reduced chlorophyll content, impaired photosynthesis, and decreased growth and yield. Leaf color variation leads to downregulation of related genes, thereby affecting chlorophyll and photosynthetic metabolism in oats, as well as starch and sucrose metabolism. These findings provide important genetic resources and phenotypic markers for oat breeding programs, contributing to our understanding of chloroplast development and photosynthetic efficiency.

Background Oat ( Avena sativa L.) is a valuable cereal crop, particularly in arid and semi-arid regions, where drought stress severely limits yield. Understanding the physiological and molecular mechanisms underlying drought tolerance in oat is essential for improving its resilience and productivity. Results This study compared the physiological and transcriptomic responses of a drought-tolerant oat cultivar (DA92-2F6, D) and a drought-sensitive cultivar (Longyan No. 3, L3) under PEG-induced drought stress at 0, 6, 24, and 72 h. Drought stress led to significant increases in malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels, with the most pronounced accumulation observed in L3. In contrast, cultivar D maintained significantly higher antioxidant enzyme activities (CAT, POD, SOD, APX; P  < 0.05), better photosynthetic performance (transpiration and net photosynthesis rates), and greater chlorophyll retention than L3. Transcriptome analysis revealed four key drought-responsive pathways: starch and sucrose metabolism, phenylpropanoid biosynthesis, plant hormone signaling, and photosynthesis regulation. Candidate genes associated with drought response included CWINV , GPI , SPP , UGP , SS , and SBE (carbohydrate metabolism); PAL , OMT1 , 4CL , and CCR (phenylpropanoid biosynthesis); and SnRK2 , HAB2 , GBF4 , JA Z1, and MYC2 (hormone signaling). Conclusions Our integrated physiological and transcriptomic analysis provides new insights into oat drought responses, identifies potential genetic markers for drought tolerance, and offers a foundation for breeding more resilient oat varieties.

The nutritional quality and yield of oats ( Avena sativa ) are often compromised by plant diseases such as red leaf, powdery mildew, and leaf spot. Sugars Will Eventually be Exported Transporters (SWEETs) are newly identified sugar transporters involved in regulating plant growth and stress responses. However, the roles of SWEET genes in biotic stress responses remain uncharacterized in oats. In this study, 13 AsSWEET genes were identified across nine chromosomes of the oat genome, all of which were predicted to contain seven transmembrane regions. Phylogenetic analysis revealed four clades of AsSWEET proteins, with high homology to SWEET proteins in the Poaceae family. Collinearity analysis demonstrated strong relationships between oat and Zea mays SWEETs. Using subcellular localization prediction tools, AsSWEET proteins were predicted to localize to the plasma membrane. Promoter analysis revealed cis-acting elements associated with light response, growth, and stress regulation. Six AsSWEET proteins were predicted to interact in a network centered on AsSWEET1a and AsSWEET11. Gene expression analysis of two oat varieties, ‘ForagePlus’ and ‘Molasses’, indicated significant expression differences in several AsSWEET genes following infection with powdery mildew or leaf spot, including AsSWEET1a , AsSWEET1b , AsSWEET2b , AsSWEET3a , AsSWEET11 , and AsSWEET16 . These SWEET genes are potential candidates for disease resistance in oats. This study provides a foundation for understanding the regulatory mechanisms of AsSWEET genes, particularly in response to powdery mildew and leaf spot, and offers insights for enhancing oat molecular breeding.

Oat sheath rot disease significantly reduces commercial oat yields, yet research on its incidence, causative pathogens, and control strategies remains limited, particularly in China. This study investigated the occurrence of oat sheath rot in major oat-producing regions of Northern China. Here, we isolated and identified two species of primary pathogenic fungi, Scopulariopsis brevicaulis and Alternaria alternata. Next, we conducted pathogenicity tests to confirm their role in the progression of oat sheath rot disease. Subsequently, we screened putative biocontrol fungi and identified Trichoderma harzianum and Trichoderma koningii as effective antagonistic biocontrol fungi. Both species demonstrated strong inhibitory effects against two primary pathogens through competitive interactions, with T. koningii achieving 100% inhibition in one test. Overall, T. harzianum and T. koningii both exerted strong inhibitory effects against pathogenic fungi via different forms of competition. Most importantly, infection experiments showed that T. harzianum and T. koningii both exerted strong antifungal effects against the pathogenic fungi that cause oat sheath rot. Taken together, our findings provide a foundation for developing biological control strategies to mitigate oat sheath rot in oat cultivation in China.

Caffeic acid O-methyltransferase (COMT) is a multifunctional enzyme involved in lignin biosynthesis and plays an important role in various primary and secondary metabolic pathways, including the plant stress response. In this study, we identified 37 AsCOMT genes from the oat ( Avena sativa ) whole-genome database, which are distributed across 11 chromosomes. Phylogenetic analysis grouped these genes into two major subfamilies, indicating that they are highly conserved during evolution and share close relationships with COMT genes from Zea mays and Oryza sativa . Cis-acting elements analysis revealed a rich presence of regulatory motifs related to plant hormone signaling and stress responses. Expression profiling of different oat varieties infected with powdery mildew and leaf spot disease showed significant upregulation or downregulation of several AsCOMT genes (e.g., AsCOMT14 , AsCOMT22 , AsCOMT24 , AsCOMT27 ). Moreover, disease-resistant oat varieties have higher lignin contents compared to susceptible varieties. Overexpression of AsCOMT23 and AsCOMT27 in tobacco leaves resulted in significantly increased lignin content, highlighting the potential of these genes in lignin biosynthesis. These results offer a preliminary exploration of the role of AsCOMT in both lignin synthesis and the plant stress response, laying the groundwork for further functional studies and potential applications in oat breeding.

Background Chemical mutagenesis coupled with molecular marker analysis is an efficient strategy for accelerating crop improvement and creating crop genetic diversity, yet optimized protocols and comprehensive evaluations chemical mutagenesis-assisted forage oats traits improvement and breeding understudied. This study aimed to assess sodium azide (SA)-induced mutagenesis in two oat varieties (Everleaf and 709) by characterizing phenotypic and molecular variations, identifying tissue-specific mutation patterns, and establishing efficient treatment parameters for breeding. Results SA treatment at > 10 mmol·L⁻ 1 caused severe germination inhibition (lethality > 60%) but maximized phenotypic variation ( CV up to 90.80% for panicle traits). By phenotypic screening, out of 767 (M 2 -M 3 ) mutants, a total of six categories of mutant phenotypes were identified: leaf traits were most frequently altered (1.02%), followed by seeds (0.39%). M 2 mutation frequencies reached 17.9–23.73%. SSR markers revealed high polymorphism (60–100% polymorphic sites, PIC 0.27–0.80), amplifying 3–9 alleles/locus. Multivariate analyses (PCA, UPGMA, and STRUCTURE) grouped 293 mutants into four genetically distinct clusters, confirming genome-wide diversity. Conclusions SA induces extensive and diverse heritable phenotypic and molecular variations in oats, with mutation spectra showing tissue-specific trends. The mutant libraries and polymorphic SSR markers developed provide a valuable resource for oat breeding and functional genomics. This work establishes a protocol for SA mutagenesis in oats and delivers mutant germplasm with broad applicability in trait improvement and genetic research.

The planting of oat varieties is influenced by factors such as their inherent traits, ecological regional climate, altitude conditions, and resistance differences, resulting in a decrease in both forage yield and quality. It is crucial to carefully select appropriate oat varieties for different ecological regions in order to enhance forage yield and quality, thereby facilitating the advancement of the grass industry. The correlation between the indices and the relationship between the indices and varieties were investigated through rigorous correlation analysis and principal component analysis. By employing gray correlation analysis, the 21 indices were transformed into 15 independent comprehensive indices. Subsequently, based on a comprehensive analysis, oat varieties suitable for cultivation in different ecological regions were identified. In this study, fifteen domestic and foreign oat varieties were cultivated in the semi-arid region of Weiqi Town and the alpine region of Damaying Town in Shandan County throughout 2023. Among the yield traits, Everleaf 126 exhibited a significantly lower plant height while possessing the largest leaf area, the highest number of effective tillers, and achieving the highest hay and seed yields (p < 0.05), which were 13,199 kg/ha and 5136 kg/ha, respectively. The plant height of Longyan No.3 in Damaying Town was significantly higher than that of other varieties. This variety also demonstrated the highest number of effective tillers, along with the greatest hay yield (7783 kg/ha) and seed yield (5033 kg/ha). Among the evaluated quality traits, Everleaf 126 in Weiqi Town exhibited the highest leaf–stem ratio, crude protein content, and crude fat content (p < 0.05). In contrast, Mengshi in Damaying Town had the highest leaf–stem ratio, while Longyan No.3 demonstrated the highest levels of crude protein and crude fat content. Furthermore, Molasses displayed the highest soluble sugar content in both locations (p < 0.05). The resistance of 15 oat varieties to pests and diseases was found to be lower in Weiqi Town compared to Damaying Town. Notably, Everleaf 126 exhibited the highest resistance to powdery mildew, red leaf disease, leaf spot disease, and aphids among the varieties tested in Weiqi Town. In contrast, Longyan No.3 demonstrated superior resistance in Damaying Town. In conclusion, based on a comprehensive analysis of the gray correlation degree, in the semi-arid region, Everleaf 126 exhibited the most superior performance, followed by Molasses and Longyan No.3. In the alpine region, Longyan No.3 demonstrated the highest overall performance, followed closely by Molasses and Mengshi. These varieties exhibit significant potential for promotion as high-yield, high-quality forage oats in semi-arid and alpine environments.

Oat (Avena sativa L.) is a vital cereal and feed crop grown worldwide, but its production is increasingly threatened by barley yellow dwarf virus (BYDV) and aphid infestations in arid and semi-arid regions, particularly in northern China. This study explores the transcriptomic and physiological responses of two oat cultivars MN10253 (resistant) and Qingyin 1 (susceptible) to BYDV at 0, 2, 8, 24, and 48 h post-infection. A combination of phytohormone profiling, differential gene expression analysis, and pathway enrichment was employed to identify mechanisms underpinning disease resistance. Comparative time-course transcriptome analysis revealed 9285 and 8904 differentially expressed genes (DEGs) in MN10253 and Qingyin 1, respectively. Key pathways such as MAPK signaling, plant–pathogen interaction, and hormone signal transduction were significantly enriched. The resistant cultivar exhibited robust activation of pattern-triggered immunity and effector-triggered immunity pathways, marked by upregulation of genes like RPS2, HSP90, and WRKY33, alongside higher expression of salicylic acid (SA)-responsive genes, such as NPR1 and PAL. Conversely, the susceptible cultivar displayed weaker or delayed activation of these defense pathways. Hormonal analysis further demonstrated higher SA accumulation in MN10253 during early infection, correlating with enhanced defense responses. In contrast, Qingyin 1 showed elevated levels of auxin and abscisic acid, which are linked to suppressed immunity. This study underscores the central role of immunity responses and phytohormone pathways in mediating oat resistance to BYDV, highlighting the tradeoff between growth and defense modulated by hormonal crosstalk. These findings advance our understanding of host–pathogen dynamics in oats and provide valuable insights for breeding disease-resistant cultivars.

Ensiling forage under low-temperature conditions often leads to poor fermentation and nutrient losses. This study evaluated the effects of a cold-tolerant Pediococcus pentosaceus OL77 strain on oat silage. Silages were prepared with or without Pediococcus pentosaceus inoculation (1 × 105 cfu/g FM). After 90 days, OL77-treated silage showed markedly higher lactic acid (45.83 vs. 30.51 g/kg DM), lower pH (3.88 vs. 4.443), and better preservation of WSC (64.68 vs. 47.60 g/kg DM) and crude protein (89.26 vs. 65.52 g/kg DM) than the control. Microbial analysis revealed accelerated colonization by Pediococcus, reduced bacterial diversity, and faster stabilization of the fermentation process. Functional predictions indicated enhanced carbohydrate and energy metabolism. These findings demonstrate that OL77 can effectively improve fermentation quality and nutrient preservation of oat silage under low-temperature conditions, offering a practical inoculant option for cold regions.