Integrated Analysis of Fatty Acid Metabolism and Transcriptome Involved in Olive Fruit Development to Improve Oil Composition

Xiaoxia Liu,Liqin Guo,Jianguo Zhang,Li Xue,Ying Luo,Guodong Rao

doi:10.3390/f12121773

Abstract

Olea europaea L. is an important oil crop with excellent nutritional properties. In this study, a full-length transcriptome combined with fatty acid composition was used to investigate the molecular mechanism of fatty acid (FA) metabolism of olive fruits at various stages of development (S1–S5). A total of 34 fatty acids (FAs) were measured using gas chromatography-mass spectrometry (GC-MS). All transcripts of FA metabolism during olive fruit development were studied, including glycolysis, fatty acid synthesis, triacylglycerol synthesis, and FA degradation. A total of 100 transcripts of 11 gene families, 68 transcripts of 12 gene families, 55 transcripts of 7 gene families, and 28 transcripts of 7 gene families were identified as encoding for enzymes involved in FA metabolism. Furthermore, one of the critical reactions in TAG metabolism is the activation of fatty acyl chains to fatty acyl CoA, which is catalyzed by long-chain acyl CoA synthetases (LACS). Phylogenetic analysis showed that 13 putative LACS-encoding genes clustered into five groups, of which two putative transcripts encoding LACS6/7 may participate in FA degradation. The aim of this study was to evaluate the fatty acid from synthesis to degradation pathways during olive fruit development to provide a better understanding of the molecular mechanism of FA metabolism during olive fruit maturation and provide information to improve the synthesis of oil components that are beneficial to human health.

Highlights

Olea europaea L. belongs to the Oleaceae family and is one of the most economically important and widely distributed trees [1,2]
With reference to the fruit-ripening process, the fruits were labelled according to five developmental stages (S1–Stage 5 (S5)) and were harvested at 50, 80, 110, 140, and 170 days after flowering (DAF)
In the 11 transcripts of PDAT, only one transcript (OE6A007392) was gradually increased during fruit development, suggesting that it plays an important role in the PDAT-mediated TAG biosynthesis pathway (Table 3). These results indicate that the four transcripts encoding DGAT (OE6A093626, OE6A108115, OE6A119597, OE6A030092) and one transcript of PDAT (OE6A007392) played crucial roles in TAG assembly, which is consistent with a previous study in which PDAT and DGAT

Summary

Introduction

Olea europaea L. belongs to the Oleaceae family and is one of the most economically important and widely distributed trees [1,2]. Due to its excellent natural health benefits, it is widely used in food preparation [3,4]. Previous studies have typically focused on the oil content of olive fruits and the FA content of the oil [7,8,9]. TAG, the main component of oil, is esterified with different fatty acids, which can be divided into saturated fatty acids (SFAs) and unsaturated fatty acids (UFAs). UFAs, such as oleic acid, linoleic acid, and linolenic acid, are more beneficial for human health than SFAs [10]. Previous studies in other species have confirmed that the oil content of the fruit or seeds first peaks and decreases slightly in the later stages of maturity [14]

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Conclusion