Carbon supply and water status regulate fatty acid and triacylglycerol biosynthesis at transcriptional level in the olive mesocarp

Abstract

The relative contribution of carbon sources generated from leaves and fruits photosynthesis for triacylglycerol biosynthesis in the olive mesocarp and their interaction with water stress was investigated. With this aim, altered carbon source treatments were combined with different irrigation conditions. A higher decrease in mesocarp oil content was observed in fruits under girdled and defoliated shoot treatment compared to darkened fruit conditions, indicating that both leaf and fruit photosynthesis participate in carbon supply for oil biosynthesis being leaves the main source. The carbon supply and water status affected oil synthesis in the mesocarp, regulating the expression of DGAT and PDAT genes and implicating DGAT1-1, DGAT2, PDAT1-1, and PDAT1-2 as the principal genes responsible for triacylglycerol biosynthesis. A major role was indicated for DGAT2 and PDAT1-2 in well-watered conditions. Moreover, polyunsaturated fatty acid content together with FAD2-1, FAD2-2 and FAD7-1 expression levels were augmented in response to modified carbon supply in the olive mesocarp. Furthermore, water stress caused an increase in DGAT1-1, DGAT1-2, PDAT1-1, and FAD2-5 gene transcript levels.Overall, these data indicate that oil content and fatty acid composition in olive fruit mesocarp are regulated by carbon supply and water status, affecting the transcription of key genes in both metabolic pathways.

Identification of miRNAs Interacting with Abscisic Acid to Regulate Fatty Acid Metabolism

“…The responsive behavior of miRNA395a and its potential target gene KAS I to ABA at the expression level (Figures 6 and 7), exhibiting opposite changes, further suggests the targeting relationship between miRNA395a and KAS I. Additionally, miR172a, which was predicted to regulate DGAT, was markedly reduced following ABA treatment (Figures 6 and 7). Notably, DGAT is a rate-limiting enzyme for triglyceride synthesis and is crucial for the accumulation of oil in seeds [52]. And expression of DGAT was up-regulated 8-fold after treatment with ABA (Figure 7).…”

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

“…This evidence confirms that the relative contribution of PDAT and DGAT enzymes to the triacylglycerols content in olive is regulated by temperature (Hernández et al 2021b), but not exclusively. Other factors may modulate the response, such as carbon supply and plant water status (Perez-Arcoiza et al 2022).…”

“…Oil accumulation begins after the lignification of the stone at about ten weeks after flowering and continues until full fruit ripening. Then, oil content accounts for around 30–50% of the fruit dry weight (Pérez‐Arcoiza et al 2022). In olive fruit, the formation of large oil droplets takes place primarily in the mesocarp cells (Bodoira et al 2015), although some oil is accumulated in the seed as well.…”

“…In olive, three DGAT1 ( OeDGAT1‐1, OeDGAT1‐2 , and OeDGAT1‐3 ) and one DGAT2 genes have been reported (Banilas et al 2011; Pérez‐Arcoiza et al 2022), whereas three PDAT genes ( OePDAT1‐1 , OePDAT1‐2 , and OePDAT2 ) have been characterized to date (Hernandez et al 2021b). OeDGAT1‐1 seems to be responsible for oil accumulation during the developmental phase with minor participation of OePDAT1‐1 , while OeDGAT2 and OePDAT1‐2 may have overlapping roles for TAG synthesis in the course of the ripening period (Banilas et al 2011; Hernandez et al 2021b).…”

Role of hydraulic traits in stomatal regulation of transpiration under different vapour pressure deficits across five Mediterranean tree crops

“…7 ) besides contributing the most in explaining the coefficient of determination of these same relationships ( Table 2 ). The relationship g s – J s / D has been used successfully to monitor g s in a continuous manner with J s and D measurements in individuals of different species and ages, and with various objectives ( Hernandez-Santana et al ., 2016 , 2018 ; Li et al , 2022 ; Perez-Arcoiza et al , 2022 ). Stomatal conductance is a key variable in plant water and carbon relations ( Buckley, 2019 ) but, unfortunately, it cannot be measured continuously and automatically as there is no technology available for this.…”