Drought severely limits the growth and development of oat (Avena sativa) seedlings. As an osmotic regulator simulating a drought environment, Polyethylene glycol (PEG) has been widely linked in response to plant drought tolerance. However, the underlying mechanism of oats’ response to PEG stress is still largely unknown. Here, we investigated the physiological and transcriptome variables of the drought-resistant oat variety DA92-2F6, and the drought-susceptible variety Longyan 3 under 15% PEG-6000 drought stress to better understand the underlying drought tolerance molecular mechanisms. The physiological results showed that except for the cell membrane permeability, the antioxidant enzyme, osmotic adjustment substance, and photosynthetic efficiency were significantly higher in the DA92-2F6 after 7 d stress. Further, 12 cDNA libraries and 123,223 unigenes were obtained by RNA-seq. A total of 33,857 differentially expressed genes (DEGs) were detected, of which two co-upregulated and three co-downregulated in four comparisons. We highlighted an analysis of the DEGs in phytohormone signal transduction pathway. The auxin, cytokinin, and brassinosteroid signaling pathways, were suppressed in Longyan 3, while abscisic acid and jasmonic acid signaling pathways were mainly activated in DA92-2F6 under drought stress. The upregulated of PP2C, ABF, SNRK2, GID1, JAZ, and MYC2 genes may enhance the drought tolerance of DA92-2F6. Taken together, these results provided a new transcript resource for the drought tolerance improvement and a reference for oat drought resistance molecular breeding.

Soil salinity is a major abiotic stress limiting crop production globally. Oat (Avena sativa) is an annual cereal with a strong salt tolerance, a high yield, and nutritional quality, although the mechanisms underlying its salt stress response remain largely unknown. We examined the physiological and transcriptomic responses of A. sativa seedlings to salt stress in tolerant cultivar Qingyongjiu 195 and sensitive cultivar 709. Under salt stress, Qingyongjiu 195 maintained a higher photosynthetic efficiency, antioxidant enzymes activity, and leaf K⁺ accumulation but a lower Na⁺ uptake than 709. RNA-seq revealed 6616 differentially expressed genes (DEGs), including 4265 up- and 2351 downregulated. These were enriched in pathways like plant–pathogen interaction, phenylpropanoid biosynthesis, and MAPK signaling. We specifically highlight DEGs involved in photosynthesis (chlG, CP47 psbB, COX2, LHCB) and antioxidants (trxA, GroES). Qingyongjiu 195 also appeared to enhance K⁺ uptake via KAT1 and AKT2 and sequester Na⁺ in vacuoles via NHX2. Additionally, HKT restricted Na⁺ while promoting K⁺ transport to shoots, maintaining K⁺/Na⁺. The expression levels of CAX, ACA, CML, CaM, and CDPK in Qingyongjiu 195 were higher than those in 709. Oats regulated Ca²⁺ concentration through CAX and ACA after salt stress, decoded Ca²⁺ signals through CML, and then transferred Ca²⁺ signals to downstream receptors through the Ca²⁺ sensors CaM and CDPK, thereby activating K⁺/Na⁺ transporters, such as SOS1 and NHX, etc. Our results shed light on plant salt stress response mechanisms and provide transcriptomic resources for molecular breeding in improving salt tolerance in oats.

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.

Leaf spot disease has become a significant limitation in oat production. 24-epibrassinolide (EBR), a highly active brassinosteroid, plays a significant role in enhancing plant immunity against various diseases by modulating physiological and molecular responses. However, the exact mechanisms by which exogenous EBR regulates plant defense to leaf spot disease are still largely unknown. In this study, we applied various concentrations of EBR (0, 0.01, 0.1, 1, and 10 mg·L⁻¹) to the leaves of oat plants that were inoculated with the Drechslera avenae pathogen. The application of 1 mg·L⁻¹ EBR significantly decreased disease index and increased chlorophyll content under pathogen inoculation while also enhancing antioxidant enzyme (SOD, CAT, and APX) activity and reducing pathogen-induced O₂^•− production rate and MDA content. Moreover, the enzymes associated with phenylpropanoid metabolism, such as PAL, C4H, and 4CL, were significantly activated by exogenous EBR. Our transcriptomic analyses further revealed that the combination of exogenous EBR and pathogen inoculation upregulated genes involved in signal transduction (BR, ABA, and MAPK), antioxidant enzyme defense systems, and phenylpropanoid and lignin-specific pathways, such as BAS1, APX, GPX, PAL, C4H, 4CL, CCR1, and CAD. Together, these findings reveal that exogenous BR application can improve resistance to Drechslera avenae-induced leaf spot disease in oats by regulating antioxidant defense systems and phenylpropanoid metabolism, which may have the potential to control leaf spot disease in oat production.

Plant protein phosphatase 2C (PP2C) represents the largest and most functionally diverse group of protein phosphatases in plants, playing pivotal roles in regulating metabolic processes, hormone signaling, stress responses, and growth regulation. Despite its significance, a comprehensive genome-wide analysis of the PP2C gene family in oat (Avena sativa L.) has remained unexplored. Leveraging the recently published oat genome, we identified 194 AsaPP2C genes, which were unevenly distributed across all 21 chromosomes. A phylogenetic analysis of PP2C classified these genes into 13 distinct subfamilies (A-L), with conserved motif compositions and exon-intron structures within each subfamily, suggesting evolutionary functional specialization. Notably, a promoter analysis revealed an abundance of stress-responsive cis-regulatory elements (e.g., MYB, MYC, ARE, and MBS), implicating AsaPP2Cs in hormones and biotic stress adaptation. To elucidate their stress-responsive roles, we analyzed transcriptomic data and identified seven differentially expressed AsaPP2C (Asa_chr6Dg00217, Asa_chr6Ag01950, Asa_chr3Ag01998, Asa_chr5Ag00079, Asa_chr4Cg03270, Asa_chr6Cg02197, and Asa_chr7Dg02992) genes, which were validated via qRT-PCR. Intriguingly, these genes exhibited dynamic expression patterns under varying stress conditions, with their transcriptional responses being both time-dependent and stress-dependent, highlighting their regulatory roles in oat stress adaptation. Collectively, this study provides the first comprehensive genomic and functional characterization of the PP2C family in oat, offering valuable insights into their evolutionary diversification and functional specialization.

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.