Epsilon Archive for Student Projects

Abstract

Cultivated oat (Avena sativa L.) is a nutritious cereal crop increasingly threatened by climate change–driven abiotic stresses such as drought and heat. While transcriptomic approaches have advanced understanding of stress responses in several major cereals, oats remain understudied under both individual and combined abiotic stresses, limiting the development of climate-resilient cultivars. In particular, the transcriptional regulation underlying oats’ stress physiology is poorly understood. This study investigated the molecular responses of two oat cultivars, ‘Active’ and ‘Guld’, that are subjected to drought, heat, and combined drought and heat stress during reproductive development, with a particular emphasis on the AP2/ERF family transcription factors. Analysis of transcriptome data indicated that the maximum number of differentially expressed genes (DEGs) was under combined stress conditions and many of them were uniquely expressed under this combined condition, demonstrating that combined stress leads to a unique regulatory network as opposed to a combined additive effect from drought and heat stress alone. Specifically, drought emerged as the dominant driver of transcriptional responses under combined drought and heat stress. In addition, ‘Guld’ possessed the highest sensitivity towards drought and combined drought and heat stress, whereas ‘Active’ had a greater sensitivity during heat stress. Several important AP2/ERF genes (ERF1, ERF003, DREB1A/B) were observed to be consistently upregulated under the three stress conditions, with many genes being substantially upregulated in ‘Active’ more than ‘Guld’, particularly under combined stress conditions. Gene functional enrichment analysis demonstrated that both ‘Active’ and ‘Guld’ were capable of maintaining their photosynthetic capacity under drought and combined stress conditions, showing a kind of adaptability, while heat alone induced pathways that used more substantial perception for environmental stresses, but did not provide consistent upregulation of photosynthetic gene processes.

Observations from the seedling assays of 'Active' under drought, heat, cold, salt, and cadmium stresses showed clear and distinct strategies for growth under each stress condition. Drought stress maintained root biomass, but reduced shoot, heat and salinity caused the greatest inhibition of growth, and cadmium and cold promoted biomass with adaptive traits. Overall, these results provide an advanced understanding of oats’ transcriptional regulation and adaptive trade-offs under multiple stresses, providing valuable targets for breeding climate-resilient cultivars.