Transcriptomic and Metabolomic Analysis of Lodging Resistance in the Basal Second Internode of Oat Stem

Oat (Avena sativa) is an important grain and feed crop, playing a significant role in agricultural production. However, lodging remains a key factor limiting oat yield and quality. Recent advances in molecular biology have shed light on the mechanisms of oat lodging resistance, particularly highlighting the critical role of lignin and cellulose content in stem strength. Nevertheless, the molecular regulatory networks governing lignin and cellulose biosynthesis in the basal second internode during the filling, milk, and dough stages remain poorly understood. In this study, we conducted a comprehensive analysis of phenotypic traits, lignin and cellulose content, and transcriptomic and metabolomic profiles in the basal second internode of two contrasting oat cultivars lodging-resistant MY1 and lodging-susceptible DY2 across three developmental stages (filling, milk, and dough). Our results identified six key genes involved in lignin synthesis (4CL3, CAD6, HRPA2, CCOAOMT, CCR1, PRX112) and five associated metabolites (L-phenylalanine, sinapropyl alcohol, sinapic acid, ferulic acid, coniferyl alcohol), as well as two cellulose synthesis-related genes (CESA4, CESA9) and one metabolite (uridine diphosphate glucose). These genes and metabolites were mainly highly expressed and enriched in MY1 during the milk stage, suggesting their potential role in enhancing lodging resistance. These findings provide valuable candidates for further research on the molecular basis of oat lodging resistance.