A comprehensive review on the colorless carotenoids phytoene and phytofluene

Carotenoids and their derivatives are versatile isoprenoids involved in many varied actions, hence their importance in the agri-food industry, nutrition, health and other fields. All carotenoids are derived from the colorless carotenes phytoene and phytofluene, which are oddities among carotenoids due to their distinct chemical structure. They occur together with lycopene in tomato and other lycopene-containing foods. Furthermore, they are also present in frequently consumed products like oranges and carrots, among others. The intake of phytoene plus phytofluene has been shown to be higher than that of lycopene and other carotenoids in Luxembourg. This is likely to be common in other countries. However, they are not included in food carotenoid databases, hence they have not been linked to health benefits in epidemiological studies. Interestingly, there are evidences in vitro, animal models and humans indicating that they may provide health benefits. In this sense, the study of these colorless carotenes in the context of food science, nutrition and health should be further encouraged. In this work, we review much of the existing knowledge concerning their chemical characteristics, physico-chemical properties, analysis, distribution in foods, bioavailability and likely biological activities

Differential transcriptomic profiles effected by oil palm phenolics indicate novel health outcomes

Abstract Background Plant phenolics are important nutritional antioxidants which could aid in overcoming chronic diseases such as cardiovascular disease and cancer, two leading causes of death in the world. The oil palm (Elaeis guineensis) is a rich source of water-soluble phenolics which have high antioxidant activities. This study aimed to identify the in vivo effects and molecular mechanisms involved in the biological activities of oil palm phenolics (OPP) during healthy states via microarray gene expression profiling, using mice supplemented with a normal diet as biological models. Results Having confirmed via histology, haematology and clinical biochemistry analyses that OPP is not toxic to mice, we further explored the gene expression changes caused by OPP through statistical and functional analyses using Illumina microarrays. OPP showed numerous biological activities in three major organs of mice, the liver, spleen and heart. In livers of mice given OPP, four lipid catabolism genes were up-regulated while five cholesterol biosynthesis genes were down-regulated, suggesting that OPP may play a role in reducing cardiovascular disease. OPP also up-regulated eighteen blood coagulation genes in spleens of mice. OPP elicited gene expression changes similar to the effects of caloric restriction in the hearts of mice supplemented with OPP. Microarray gene expression fold changes for six target genes in the three major organs tested were validated with real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and the correlation of fold changes obtained with these two techniques was high (R2 = 0.9653). Conclusions OPP showed non-toxicity and various pleiotropic effects in mice. This study implies the potential application of OPP as a valuable source of wellness nutraceuticals, and further suggests the molecular mechanisms as to how dietary phenolics work in vivo.</p

Plant carotenoids: molecular genetics and regulation

The potential health benefits of carotenoids as anti-cancer and antioxidant agents have recently been demonstrated. In particular, lycopene and ß-carotene have lately been shown to be able to reduce the risk of chronic conditions of coronary heart disease, certain cancers and macular degeneration. The findings have led to rapid development in the field aimed at understanding the biosynthetic pathway and ultimately engineering the carotenoid content. This article reviews the recent progress made in the areas of molecular genetics and genetic engineering of plant carotenoids. The latest development in the regulatory mechanisms controlling the pathway is also highlighted. Finally, this review also highlights some recent progress made in oil palm carotenoid research, especially the molecular cloning of genes encoding key enzymes of the biosynthetic pathway and efforts to improve oil palm carotenoid content

Candidate genes linked to QTL regions associated with fatty acid composition in oil palm

© 2020, Institute of Molecular Biology, Slovak Academy of Sciences. The present study searched for candidate genes in five linkage groups (LGs) - T2, T3, OT4, OT6 and T9 hosting the QTLs associated with iodine value (IV) and fatty acid composition (FAC) in an oil palm interspecific hybrid population. Each of the five LGs was successfully anchored to its corresponding chromosomal segment where, a wider repertoire of candidate genes was identified. This study further revealed a total of 19 candidate genes and four transcription factors involved in biosynthesis of fatty acids, lipids (including triacylglycerol) and acetyl-CoA, glycosylation and degradation of fatty acids. Their possible involvement in regulating the levels of saturation are discussed. In addition, 22 candidate genes located outside the QTL intervals were also identified across the interspecific hybrid genome. A total of 92 SSR markers were developed to tag the presence of these candidate genes and 50 were successfully mapped onto their respective positions on the genome. The data obtained here complements the previous studies, and collectively, these QTL-linked candidate gene markers could help breeders in more precisely selecting palms with the desired FAC

Expression of fatty acid and triacylglycerol synthesis genes in interspecific hybrids of oil palm

© 2020, The Author(s). Evaluation of transcriptome data in combination with QTL information has been applied in many crops to study the expression of genes responsible for specific phenotypes. In oil palm, the mesocarp oil extracted from E. oleifera × E. guineensis interspecific hybrids is known to have lower palmitic acid (C16:0) content compared to pure African palms. The present study demonstrates the effectiveness of transcriptome data in revealing the expression profiles of genes in the fatty acid (FA) and triacylglycerol (TAG) biosynthesis processes in interspecific hybrids. The transcriptome assembly yielded 43,920 putative genes of which a large proportion were homologous to known genes in the public databases. Most of the genes encoding key enzymes involved in the FA and TAG synthesis pathways were identified. Of these, 27, including two candidate genes located within the QTL associated with C16:0 content, showed differential expression between developmental stages, populations and/or palms with contrasting C16:0 content. Further evaluation using quantitative real-time PCR revealed that differentially expressed patterns are generally consistent with those observed in the transcriptome data. Our results also suggest that different isoforms are likely to be responsible for some of the variation observed in FA composition of interspecific hybrids

Characterisation of Oil Palm Acyl-CoA-Binding Proteins and Correlation of their Gene Expression with Oil Synthesis

Acyl-CoA-binding proteins (ACBPs) are involved in binding and trafficking acyl-CoA esters in eukaryotic cells. ACBPs contain a well-conserved acyl-CoA-binding domain (ACBD). Their various functions have been characterized in the model plant Arabidopsis and, to a lesser extent, in rice. In this study, genome-wide detection and expression analysis of ACBPs were performed on Elaeis guineensis (oil palm), the most important oil crop in the world. Seven E. guineensis ACBPs were identified and classified into four groups according to their deduced amino acid domain organization. Phylogenetic analysis showed conservation of this family with other higher plants. All seven EgACBPs were expressed in most tissues while their differential expression suggests various functions in specific tissues. For example, EgACBP3 had high expression in inflorescences and stalks while ACBP1 showed strong expression in leaves. Because of the importance of E. guineensis as an oil crop, expression of EgACBPs was specifically examined during fruit development. EgACBP3 showed high expression throughout mesocarp development, while EgACBP1 had enhanced expression during rapid oil synthesis. In endosperm, both EgACBP1 and EgACBP3 exhibited increased expression during seed development. These results provide important information for further investigations on the biological functions of EgACBPs in various tissues and, in particular, their roles in oil synthesis

RT-PCR amplification and cloning of partial DNA sequence coding for oil palm (Elaeis oleifera) phytoene synthase gene

The potential health benefits of carotenoids as anti cancer and antioxidant agents have recently been demonstrated. Oil palm, Elaeis oleifera in particular, is known to be the richest natural source for carotene. However, the species has not been commercially exploited due to its extremely low oil yield. The current work describes the isolation of a cDNA clone coding for phytoene synthase (psy) from E. oleifera by RT-PCR amplification. A pair of psy gene specific primers was successfully used to amplify a 899 bp fragment that codes for a partial length (300 amino acids) of oil palm psy. The DNA and amino acid sequences were shown to share a high level of identity to phytoene synthase from other plants at about 83%. Further analysis also showed the presence of conserved aspartate-rich catalytic domains within the clone. Work was also carried out to obtain the expression pattern of oil palm psy in developing fruits by real-time PCR analysis. Results indicated that the gene is highly regulated during the course of oil palm fruit development. The pattern of psy expression was shown to be well correlated to the accumulation of lutein in the young mesocarp and α- and β-carotenes in the older tissues. This observation demonstrated that oil palm psy was highly regulated for tissue development and accumulation of carotenes for storage

Comparison of quantitative trait loci (QTLs) associated with yield components in two commercial Dura × Pisifera breeding crosses

The high yielding tenera is the commercial oil palm planting material of choice in Southeast Asia. Notwithstanding this, there is continuous effort to further improve the yield and one way to do this is by addressing the yield components (YCs ). Using 4,451 SNP and over 600 SSR markers , this study revealed quantitative trait loci (QTL) associated with YCs in two breeding populations, a Deli dura x Yangambi pisifera (P2) and a Deli dura x AVROS pisifera (KULIM DxP). Thirteen and 29 QTLs were identified in P2 and KULIM DxP, respectively . They were compared to other YC-linked QTLs reported previously for different genetic backgrounds by mapping the QTL-linked markers to the oil palm genome . The comparison revealedfour common chromosomes containing QTLs influencing various YCs . The results reveal the possible presence of closely linked loci or pleiotropic genes influencing YCs in oil palm. Exploiting the genome data has also facilitated the discovery of candidate genes within or near the QTL regions including those related to glycosylation, fatty acid and oil biosynthesis, and development of flower, seed and fruit

Characterization of oil palm Acyl-CoA-Binding proteins and correlation of their gene expression with oil synthesis

Acyl-CoA-binding proteins (ACBPs) are involved in binding and trafficking acyl-CoA esters in eukaryotic cells. ACBPs contain a well-conserved acyl-CoA-binding domain (ACBD). Their various functions have been characterized in the model plant Arabidopsis and, to a lesser extent, in rice. In this study, genome-wide detection and expression analysis of ACBPs were performed on Elaeis guineensis (oil palm), the most important oil crop in the world. Seven E. guineensis ACBPs were identified and classified into four groups according to their deduced amino acid domain organization. Phylogenetic analysis showed conservation of this family with other higher plants. All seven EgACBPs were expressed in most tissues while their differential expression suggests various functions in specific tissues. For example, EgACBP3 had high expression in inflorescences and stalks while ACBP1 showed strong expression in leaves. Because of the importance of E. guineensis as an oil crop, expression of EgACBPs was specifically examined during fruit development. EgACBP3 showed high expression throughout mesocarp development, while EgACBP1 had enhanced expression during rapid oil synthesis. In endosperm, both EgACBP1 and EgACBP3 exhibited increased expression during seed development. These results provide important information for further investigations on the biological functions of EgACBPs in various tissues and, in particular, their roles in oil synthesis

The oil palm VIRESCENS gene controls fruit colour and encodes a R2R3-MYB

Oil palm, a plantation crop of major economic importance in Southeast Asia, is the predominant source of edible oil worldwide. We report the identification of the VIRESCENS (VIR) gene, which controls fruit exocarp colour and is an indicator of ripeness. VIR is a R2R3-MYB transcription factor with homology to Lilium LhMYB12 and similarity to Arabidopsis PRODUCTION OF ANTHOCYANIN PIGMENT1 (PAP1). We identify five independent mutant alleles of VIR in over 400 accessions from sub-Saharan Africa that account for the dominant-negative virescens phenotype. Each mutation results in premature termination of the carboxy-terminal domain of VIR, resembling McClintock's C1-I allele in maize. The abundance of alleles likely reflects cultural practices, by which fruits were venerated for magical and medicinal properties. The identification of VIR will allow selection of the trait at the seed or early-nursery stage, 3-6 years before fruits are produced, greatly advancing introgression into elite breeding material