Genotypic Differences in Triacylglycerol-Centered Lipid Metabolism at the Kernel Developing Stage in Three Representative Yunnan Macadamia Cultivars Revealed by Integrated Omics

Macadamia integrifolia is an economically important woody oil crop valued for its high monounsaturated fatty acid content and excellent kernel nutritional quality. Although it has great industrial potential, variety-related differences in lipid metabolism and kernel quality are still poorly understood. Resolving these differences will support targeted quality improvement and molecular-breeding efforts. In this study, three representative macadamia cultivars, namely DS1, GR1 and O.C., which are widely cultivated in Yunnan province of China, were employed to investigate the dynamic variations in kernel quality traits across three physiological stages. Integrated transcriptomic, metabolomic, and lipidomic analyses were applied at the kernel development stage to characterize the metabolic differentiation. Multi-omics results revealed distinct carbon allocation and lipid accumulation patterns observed among the three cultivars. Variety-related differences in oil yield and nutrient profiles were associated with altered gene expressions and metabolite levels linked to fatty acid biosynthesis, triacylglycerol (TG) assembly and oil-body formation. Differences in lipid and carbon metabolite accumulation also contributed to these phenotypic variations. This study preliminarily identified candidate genes and pathways associated with TG-centered lipid metabolism in developing macadamia kernels at a critical developmental stage, based on samples collected from single trees per cultivar.