Changes in gene expression and metabolic profile of drupes of Olea europaea L. cv Carolea in relation to maturation stage and cultivation area

Abstract

Background Olive (Olea europaea L.) is an emblematic oil tree crop in the Mediterranean basin. Currently, despite olive features as a moderately thermophilic species, its cultivation is worldwide spreading due to the health-related impact of olive products on human nutrition. A point of concern for the expanding olive cultivation is related to the influence that, in addition to genotype, environmental factors exerts on drupe development and metabolism with consequent impact on fruit key traits. In this context, the aim of the present work was to gain further information on the genetic networks controlling drupe maturation phase and, mainly, on their modulation in response to environmental cues. Results To achieve this goal, a comparative transcriptome-wide investigation was carried out on drupes of Olea europaea cultivar Carolea, collected from plants growing in areas at different altitude level and therefore experiencing different climatic conditions. Two maturation stages of drupe were analysed: green mature and turning-purple. Metabolic characterization of drupe was also performed. At both transcriptomic and metabolic level differences were detected in the pathway of fatty acids (FAs) and phenol compounds, in relation to both drupe maturation stage and cultivation area. Among the most relevant differences detected during the transition from GM to TP stages there were: the upregulation of FADs genes in the drupes of population growing at 700 masl, the upregulation of phenol biosynthesis-related genes in drupes growing at 10 and 200 masl and very interestingly the downregulation of specific genes involved in secoiridoids production in drupes growing at 700 masl. Globally, these results suggested that stability of FAs and phenols, mainly of secoiridoids group, is promoted at high altitude, while at lower altitude phenol biosynthesis is prolonged. Conclusion The obtained results showed a differential modulation of genetic pathways related to olive compound quality in relation to the cultivation area, likely imposed by the different temperature impending at each altitude. The derived molecular information appears of interest for both breeding and biotechnological programs of olive species, especially with respect to the modulation of antioxidant secoiridoid compounds which play a key role in conferring both sensorial and healthy characteristic to olive products.

Genome-Wide Identification, Evolutionary Patterns, and Expression Analysis of bZIP Gene Family in Olive (Olea europaea L.)

“…The gene expression levels of OeSACPD1 and -2 in 'A' in our study were similar to those in a previous report in the same variety, peaking in the early stages (July to August) and then decreasing [66]. Moreover, the expression level of OeFAD2.2, which is considered to be mainly responsible for the linoleic acid content in olive oil, as reported by Hernandez [64] and Bruno [73], was higher than that of OeFAD2.5 in our study, indicating that OeFAD2.5 may not be a significant factor affecting the oil content of mesocarp.…”

“…Several researchers have reported that the composition of olive oil fatty acids, particularly oleic acid, fluctuated according to the variety [68,71,72]. The variation of OeFAD2 [64,73], OeFAD3 [65], and OeSACPD [66,74] gene expression is the main factor that affects the composition of fatty acids [37]. The gene expression levels of OeSACPD1 and -2 in 'A' in our study were similar to those in a previous report in the same variety, peaking in the early stages (July to August) and then decreasing [66].…”

“…, 10, 12, 22, 27, 37, 50, 52, 53, 78, 84, 85, 91, 94, and 99) and November (OebZIP22,39,46,48,50,52,53,59,65,70,73, 79, 84, 92, 93, and 99), respectively. A total of 5 OebZIP genes…”

Eleven Monovarietal Extra Virgin Olive Oils from Olives Grown and Processed under the Same Conditions: Effect of the Cultivar on the Chemical Composition and Sensory Traits

“…shows different values in fatty acid composition, phenolic content and oxidative stability [ 19 , 20 , 21 ]. Since pedoclimatic aspects, olive ripeness, harvesting time and the extraction system, strongly impact on the chemical composition and sensory properties of oils [ 22 , 23 , 24 ], it is recommended to control these factors when studying characteristics of MEVOOs. Within the heritage of Mediterranean diet products, MEVOOs represent precious contributions, whose sensory and healthy properties are explained by chemical compositional peculiarities, in many cases not yet investigated.…”

Transcriptome and Hormone Analyses Revealed Insights into Hormonal and Vesicle Trafficking Regulation among Olea europaea Fruit Tissues in Late Development

“…Olive trees ( Olea europaea L.) are one of the most economically important fruit trees worldwide for the oil of its fruit, and has high intra-specific genetic variation with a genome size of about 1800 Mb [ 8 , 9 ]. Until now, the study of gene function in the olive has been fundamentally advanced by the availability of whole genome sequences [ 10 , 11 , 12 ], while several transcriptomic, proteomic, and metabolic studies have been developed in olive fruit [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. However, these studies concern only a few genotypes and little is still known about olive-fruit biology.…”