Molecular basis of fatty acid composition diversity in different avocado cultivars

Avocado (Persea americana Mill.), an evergreen tree belonging to the Persea genus in the Lauraceae family, is native to Central America and Mexico. Avocado fruit has become a global “superfood” and globally important economic crop because of its exceptionally high oil content and unique nutritional composition. Elucidating the differences in fatty acid composition among avocado cultivars and the underlying molecular regulatory mechanisms is highly important for the targeted breeding of high-quality cultivars of avocado. In this study, we systematically investigated the variation in and regulatory mechanisms of fatty acid composition in the fruits of five major avocado cultivars (‘Hass’, ‘Zutano’, ‘Fuerte’, ‘Reed’, and ‘Pinkerton’). Through GC‒MS analysis, significant differences in fatty acid profiles were detected among the cultivars. The ‘Fuerte’ cultivar presented the highest monounsaturated fatty acid content (70.71%), while the ‘Hass’ cultivar presented the greatest abundance of polyunsaturated fatty acids (22.21%). Transcriptome analysis revealed distinct expression profiles of genes involved in fatty acid metabolic pathways across different cultivars. Moreover, WGCNA identified the ω-6 fatty acid desaturase genes FAD2.1 and FAD2.2, which catalyze the conversion of oleic acid to linoleic acid, as key genes regulating linoleic acid biosynthesis. Further investigation revealed that the transcription factors PaARF16 and PaZIP18 modulate the transcriptional activity of FAD2.1 by binding to its promoter region, providing potential targets for molecular breeding improvements. This study revealed the differences in fatty acid composition among different avocado cultivars and a potential molecular basis in fatty acid metabolism, providing new insights into the molecular mechanisms underlying avocado oil quality development and a genetic resource for improving oil quality.