Coupling proteomics and lipidomics for insights into regulation of oat (Avena sativa) grain lipid synthesis

Breeding is a feasible strategy to develop low-oil oat (Avena sativa) varieties, which aligns with specific processing needs and dietary preferences. To identify factors contributing to a low-oil phenotype, we optimised a sequential extraction workflow for proteomics and lipidomics analyses on five Australian oat varieties with different oil contents. Oat oil content positively correlated with abundances of several proteins in lipid synthesis pathways, suggesting their key lipid regulatory roles. Lipidomics was used to complement proteomics data and revealed a negative correlation between triacylglycerols and other lipid classes such as diacylglycerols and phospholipids. Spatial regulation of lipids was also investigated using matrix-assisted laser desorption and ionisation mass spectrometry imaging (MALDI-MSI) and proteomics analysis of tissue-enriched fractions, providing further insights into distinct physiological functions of the endosperm and embryo. Pathway enrichment analysis indicated different nutrient-synthesising capacity in high- vs low-oil varieties. Findings from this study may support future breeding for low-oil oats.