Molecular and biochemical analyses of avocado (Persea americana) reveal differences in the oil accumulation pattern between the mesocarp and seed during the fruit developmental period

The fatty acids in avocado mesocarp and seed are crucial constituents and possess the critical influence in commercializing for fresh-eating consumption and industrially oil processing. Hence, plant physiologists express an interest in better understanding tissue-specific oil biosynthesis and the associated regulatory network between the developing avocado (Persea americana) mesocarp and seed, which will contribute to improving the quality and utility of avocado fruits in food and industrial processing. The results revealed the ever-increasing and fluctuating trends in the oil accumulation in the developing avocado mesocarp and seed, respectively. Additionally, striking differences in the lipid droplets between the developing mesocarp and seed were revealed in confocal microscopy images. The tissue-specific transcription of lipid-related genes contributing to fatty acid synthesis, triacylglycerol assembly, and triacylglyceml storage was examined, and four highly transcribed lipid-related genes (PaFAB2, PaACP4-2, PaDGAT2, and PaFAD2-1) involved in FA synthesis and TAG assembly were indicative of the key roles in oil accumulation variation between the developing avocado mesocarp and seed. A weighted gene co-expression network analysis uncovered two highly expressed lipid-related hub transcription factors (PaPBS1-1 and PaRAP2-3) that each played a crucial part in oil biosynthesis regulatory network in avocado mesocarp and seed, respectively. Moreover, our data also revealed that five highly expressed cis-acting lncRNAs (PB.19359.1, PB.6205.1, PB.4443.3, PB.12340.3, and PB.19743.2) may give rise to the observably differences in the oil accumulation between the developing mesocarp and seed. Our data may be useful for characterizing tissue-specific oil accumulation at the multifaceted levels, thereby identifying four functional genes, two transcription factors, and five lncRNAs for improving the oil production of related plant species.