Introduction: Oat (Avena nuda L.) and common vetch (Vicia sativa L.) intercropping in the northern regions of China has resulted in substantial production capabilities. However, there is currently a dearth of comprehensive research on whether this intercropping system can enhance productivity through increased sowing densities and underlying interspecies interaction mechanisms.Methods: A two-year field experiment was conducted in 2022 and 2023 to investigate the yield, biological efficiency, economic efficiency, and competition indicators of oats and common vetch in a high-density intercropping system. Two cropping patterns (monocropping and intercropping) and five sowing densities (D1: 4.5×10⁶ plants ha^-1; D2:5.4×10⁶ plants ha^-1; D3:6.3×10⁶ plants ha^-1; D4: 7.2×10⁶ plants ha^-1; and D5: 8.1×10⁶ plants ha^-1) were arranged in a randomized block design.Results: At the same sowing density, the intercropped oats exhibited greater grain yield than the monocultures. Increasing the oat sowing density significantly enhanced oat yield, with the D3 level in intercropping showing the highest yield increase, ranging from 30.98% to 31.85%, compared with the monoculture. The common vetch intercropping grain yield was maximized in the D2 treatment. The land equivalent ratio was maximized at the D2 level in both years and was significantly higher than D1, with the land equivalent coefficient, system productivity index, and percentage yield difference suggesting that increasing oat sowing densities improved the productivity of the intercropping system, with the best performance observed at the D2 level. For both years, the proportionate actual yield loss of oat was the highest at the D3 level; significantly surpassing D1, proportionate actual yield loss of common vetch and actual yield loss were the highest at level D2, both significantly surpassing D1. These indicates that appropriate densification contributes to the realization of the advantages of intercropping. With an increased oat sowing density, the economic benefits of the intercropping system were maximized at the D2 and D3 levels. Regarding intercropping competition, oat was the dominant crop under different sowing densities (Aggressivity for oat (A_O)>0, relative crowding coefficient for oat (K_O)>1, competition ratio for oat (CR_O)>1), whereas common vetch was the inferior crop. Compared with the D1 level, the D2 level harmonized the aggressivity, competitive ratio, and relative crowding coefficients of oat and common vetch, significantly increasing crowding coefficient for common vetch (K_V) and competition ratio for common vetch by 19.76% to 21.94% and 4.80% to 7.51%, respectively, while reducing K_O and CR_O.Discussion: This result suggests that in the intercropping of common vetch and oat in alpine regions, rational densification can harmonize interspecific competition and thus improve the biological efficiency and economic benefits of intercropping systems.

Oat (Avena sativa L.) is an annual grass that has a high nutritional value and therapeutic benefits. β-glucan is one of the most important nutrients in oats. In this study, we investigated two oat varieties with significant differences in β-glucan content (high β-glucan oat varieties BY and low β-glucan content oat variety DY) during different filling stages. We also studied the transcriptome sequencing of seeds at different filling stages. β-glucan accumulation was highest at days 6-16 in the filling stage. Differentially expressed genes (DEGs) were selected from the dataset of transcriptome sequencing. Among them, three metabolic pathways were closely related to the biosynthesis of β-glucan by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, including xyloglucan:xyloglucosyl transferase activity, starch and sucrose metabolism, and photosynthesis. By analyzing the expression patterns of DEGs, we identified one CslF2 gene and 32 transcription factors. Five modules were thought to be positively correlated with β-glucan accumulation by weighted gene co-expression network analysis (WGCNA). Moreover, the expression levels of candidate genes obtained from the transcriptome sequencing were further validated by quantitative real-time PCR (RT-qPCR) analysis. Our study provides a novel way to identify the regulatory mechanism of β-glucan synthesis and accumulation in oat seeds and offers a possible pathway for the genetic engineering of oat breeding for higher-quality seeds.

Oats (Avena sativa L.) are a nutritionally important cereal crop, but the molecular mechanisms regulating protein and amino acid accumulation during grain development remain poorly understood. Therefore, in this study, two oat varieties (HZ and MC) with significantly different grain protein contents were used as experimental materials. For the grains of these two varieties at different developmental stages, we conducted grain protein content determination, widely targeted metabolite detection, and transcriptome sequencing. Integrated transcriptomic and metabolomic analyses of two oat varieties (high-protein HZ and low-protein MC) revealed dynamic changes during grain filling. Key findings include: (1) The 10–20 days after flowering (DAF) period was critical for protein accumulation, with HZ showing higher expression of genes involved in carbon skeleton generation (e.g., isocitrate dehydrogenase, malate dehydrogenase) and amino acid biosynthesis (e.g., glutamate decarboxylase); (2) Weighted gene coexpression network analysis identified modules strongly correlated with protein content, including the blue module (r = 0.92, p < 0.01); (3) KEGG enrichment highlighted central roles for glycolysis, TCA cycle, and amino acid metabolism pathways; (4) A regulatory network for protein and amino acid accumulation was constructed, identifying 157 candidate genes and 7 metabolites. Four key genes (GLA, PFK, PGK, TIM) and a transcription factor (AP2/ERF-ERF ) were identified as critical regulators; (5) qRT-PCR validated 10 candidate genes, with expression patterns consistent with RNA-Seq data (R² = 0.72–0.85). This study elucidates the metabolic and transcriptional networks underlying protein accumulation in oat grains, providing targets for molecular breeding to enhance nutritional quality.

Background Oats (Avena sativa L.) are a nutritionally important cereal crop, but the molecular mechanisms regulating protein and amino acid accumulation during grain development remain poorly understood. Results Integrated transcriptomic and metabolomic analyses of two oat varieties (high-protein HZ and low-protein MC) revealed dynamic changes during grain filling. Key findings include: (1) The 10–20 days after flowering (DAF) period was critical for protein accumulation, with HZ showing higher expression of genes involved in carbon skeleton generation (e.g., isocitrate dehydrogenase, malate dehydrogenase) and amino acid biosynthesis (e.g., glutamate decarboxylase); (2) Weighted gene coexpression network analysis identified modules strongly correlated with protein content, including the blue module (r = 0.92, p < 0.01); (3) KEGG enrichment highlighted central roles for glycolysis, TCA cycle, and amino acid metabolism pathways; (4) A regulatory network for protein and amino acid accumulation was constructed, identifying 157 candidate genes and 7 metabolites. Four key genes (GLA, PFK, PGK, TIM ) and a transcription factor (AP2/ERF-ERF) were identified as critical regulators; (5) qRT-PCR validated 10 candidate genes, with expression patterns consistent with RNA-Seq data (R² = 0.72–0.85). Conclusions This study elucidates the metabolic and transcriptional networks underlying protein accumulation in oat grains, providing targets for molecular breeding to enhance nutritional quality.