Transcriptional regulation of oil synthesis and fatty acid desaturation in olive fruit under elevated growth temperature

GARCIA-INZA, G. P.; HERNANDEZ, MARIA LUISA; MISERERE, ANDREA; SICARDO, MARÍA DOLORES ; MARTÍNEZ-RIVAS, JOSÉ MANUEL; ROUSSEAUX, M. CECILIA

Physiologia Plantarum

John Wiley and Sons Inc

Año: 2024 vol. 176

Ambient temperature during olive fruit growth modulates oil content and fatty acidcomposition. However, the mechanisms behind their regulation are not completelyunderstood. In this work, the transcriptional regulation of oil synthesis and fattyacid desaturation were evaluated by manipulating air temperature in the field.Three-year-old trees of cultivars ‘Arbequina’ and ‘Coratina’ were placed in open-topchambers (OTC) where control or elevated air temperatures were applied early in theoil accumulation phase, and fruits were sampled after 10 or 36 days of exposure.Upon elevated temperature, the oil content in ‘Coratina’ mesocarp tissue decreasedless than in ‘Arbequina’ compared to their respective controls. However, the oleicacid content of ‘Coratina’ was more sensitive to temperature. The cultivar-dependentresponses were mainly explained by differential gene expression. In ‘Arbequina’, thedownregulation of genes involved in triacylglycerol biosynthesis (OeDGAT1-2, OeDGAT2,OePDAT1-1, and OePDAT1-2), upon elevated temperature explains the decreasein oil content, whereas the downregulation of the fatty acid desaturasesgenes (OeSAD1, OeSAD3, OeFAD2-1, OeFAD2-2, and OeFAD2-5) decreased theoleic/linoleic ratio. In contrast, in ‘Coratina’, OePDAT1-2 downregulation explainsthe fluctuation in oil content, but the increased expression of three members ofthe OeFAD2 gene family was responsible for the oleic/linoleic ratio. This knowledgecontributes to developing an integrated strategy for olive production underhigh temperatures, and the analysis of the expression of key genes could be usedas a selection criterion in genetic improvement programs for the adaptation ofolive cultivars to global warming.