Academic literature on the topic 'Lutein esterification'

Research on enhancing lutein content in microalgae has made significant progress in recent years. However, strategies are needed to address the possible limitations of microalgae as practical lutein producers. The capacity of lutein sequestration may determine the upper limit of cellular lutein content. The preliminary estimation presented in this work suggests that the lutein sequestration capacity of the light-harvesting complex (LHC) of microalgae is most likely below 2% on the basis of dry cell weight (DCW). Due to its nature as a structural pigment, higher lutein content might interfere with the LHC in fulfilling photosynthetic functions. Storing lutein in a lipophilic environment is a mechanism for achieving high lutein content but several critical barriers must be overcome such as lutein degradation and access to lipid droplet to be stored through esterification. Understanding the mechanisms underlying lipid droplet biogenesis in chloroplasts, as well as carotenoid trafficking through chloroplast membranes and carotenoid esterification, may provide insight for new approaches to achieve high lutein contents in algae. In the meantime, building the machinery for esterification and sequestration of lutein and other hydroxyl-carotenoids in model microorganisms, such as yeast, with synthetic biology technology provides a promising option.

A high carotenoid content is important for the production of pasta from durum wheat (Triticum durum Desf.) and yellow alkaline noodle from common wheat (T. aestivum L.). Carotenoid esters are more stable than free carotenoid during storage and processing, and thus they allow a higher retention through the food chain. Chromosome 7D carries gene(s) for lutein esterification. The aim of this study was the physical mapping of the gene(s) for lutein esterification on chromosome 7D and the identification of candidate genes for this trait. We developed crosses between a set of deletion lines for chromosome 7D in Chinese Spring (CS) background and the CS–Hordeum chilense substitution line CS(7D)7Hch. The F2 progeny derived from the deletion line 7DS4 produced a lower amount of lutein esters, which indicates that the main gene for lutein esterification is in the region of chromosome 7D lacking in 7DS4. Other gene(s) are contributing to lutein esterification because small amounts of lutein esters are produced in 7DS4. Genotyping by DArTSeq revealed that 7DS4 lacks a 127.7 Mb region of 7DS. A set of 10 candidate genes for lutein esterification was identified by using the wheat reference genome sequence along with the Wheat Expression Browser. This region contains the Lute locus previously identified in a different genetic background. Four genes with acyltransferase or GDSL esterase/lipase activity were identified in the vicinity of Lute. Our results indicate that the gene TraesCS7D01G094000 is a likely candidate for Lute but the gene TraesCS7D01G093200 cannot be ruled out. The candidate genes reported in this work are worthy for further investigation.

Carotenoids are essential in the human diet for their important functions in health. Besides, they are responsible for the yellow pigments desirable for industrial quality in durum wheat. The remarkable carotenoid content of durum wheat endosperm is mostly due to lutein. However, lutein esters have not been previously detected in durum wheat as in other cereals such as common wheat, tritordeum or Hordeum chilense. Esterification increases carotenoid stability and allows greater retention and accumulation through the food chain. Therefore, carotenoid esterification is revealed as a new key target in breeding. We characterized the carotenoid profile of 156 accessions of the Spanish durum wheat collection, searching for landraces with esterification ability. Interestingly, four accessions produced lutein monoesters and diesters. Also, traces of lutein monoesters were detected in eleven accessions. The identification of the first durum wheat accessions with esterification ability reported herein is a remarkable advance for carotenoid biofortification. Furthermore, variation for the relative content of zeaxanthin, α-carotene and β-carotene was also observed. This diversity for the β,ε and β,β branches of the carotenogenic pathway also represents a new opportunity for breeding for specific carotenoids in biofortification programs.

The high carotenoid content in tritordeum (×Tritordeum Ascherson et Graebner) grains is derived from its wild parent, Hordeum chilense Roem. et Schulz. Phytoene synthase 1 (Psy1) is located on chromosome 7HchS and plays a major role in this trait. This study investigates the impact of the introgression of chromosome 7Hch into common wheat background on carotenoid composition, including xanthophylls esterified with fatty acids (monoesters and diesters). All of the genetic stocks carrying Psy1 from H. chilense increased their carotenoid content relative to common wheat. In addition, significant changes in the carotenoid profile were detected in different genetic stocks. The most relevant was the increase in content of lutein diesters when both 7Hch and 7D were present, which indicates the existence of genes involved in the esterification of xanthophylls in both chromosomes. Furthermore, our results suggest that 7Hch genes preferentially esterify lutein with palmitic acid, whereas 7D is either indifferent to the fatty acid or it prefers linoleic acid for lutein esterification. The involvement and complementarity of 7Hch and 7D are highly significant considering the scarcity of previous results on lutein esterification in wheat.

The functionalized graphitic carbon nitride nanosheets (g-C₃N₄-Ns) as the immobilized carrier for the accommodation of Candida antarctica lipase B (CALB), which obtains the highest esterification rate (92%) in lutein esters synthesis.

Preservation of lutein concentrations in wheat-based end-products during processing is important both for product quality and nutritional value. A key constituent involved in lutein degradation is endogenous lipoxygenase. Lutein and lutein ester concentrations were compared at intervals during storage of noodle sheets prepared from flour of wheat varieties representing a range in lipoxygenase activity, as well as in different mill streams and in different grain tissues. Higher lipoxygenase concentration was associated with an increased loss of free lutein and lutein mono-esters whereas lutein diesters appeared to be more resistant to degradation. Lutein degradation was reduced in the presence of a lipoxygenase inhibitor, when noodle sheets were heated to destroy enzyme activity or when pH was increased. In addition, three populations were used to investigate the genetic control of lipoxygenase. A previously reported mutation of Lpx-B1.1 was associated with a reduction in activity from high to intermediate whilst a new locus on chromosome 4D was associated with variation between intermediate and near-zero. The gene underlying the 4D locus is a putative lipoxygenase. Stability of lutein could be improved by deployment of the mutations at the 4B and 4D loci and/or by post-harvest storage of grain under conditions that promote esterification.

Lutein is an important micronutrient for humans as well as being the primary contributor to the pale creamy to yellow colour of bread wheat and durum based products but tends to be unstable against heat and UV light. During post harvest storage of bread wheat grain some of the lutein may be converted to mono- and di-fatty acid esters that appear to be more stable forms of lutein. The aims of the work presented in this thesis were: to study the effects of temperature on lutein esterification; to compare the relative stability of free lutein and lutein esters in grain stored under wide temperatures and conditions; to confirm that esterification is an enzymic process; to examine the genetic control mechanisms; to attempt to identify the enzyme and the endogenous substrate source of fatty acids; and finally to compare esterification in wheat grain with the same process in banana fruit tissues. This study utilised a high lutein, ester forming bread wheat, Triticum aestivum L. cv DM5685*B12, a non-ester forming bread wheat cv Haruhikari and a high lutein durum wheat, Triticum durum L cv Kamilaroi, that like many durum cultivars does not form lutein esters. Reverse phase high pressure liquid chromatography (RP-HPLC) was used to quantify the lutein and lutein ester concentrations. Lutein esterification was strongly favoured by low relative humidity (8% RH) and followed a first order reaction rate. The maximum rate of lutein esterification was at ≈80°C, however the optimum temperature for maximum synthesis with minimum degradation was between 50 and 60°C. No ester synthesis was observed at temperature higher than 120ºC. These data were consistent with an enzyme participating in the esterification reaction. Lutein ester was found to be more stable than free lutein with a substantially longer shelf life at a temperature of 60°C. An attempt to establish a bioassay system to study esterification was only partially successful since only very low levels of esterification were achieved in reconstituted samples. Further investigation would be required to optimise the process. The limited data did provide suggestive evidence that free fatty acids were probably not involved, rather the fatty acids were more likely to be derived from phospholipids via an acyltransferase reaction. A hexane-soluble fraction derived from a non-ester forming durum, Kamilaroi, was the only substrate that in the presence of a crude enzyme extract and free lutein gave a significant formation of lutein ester. As esterification appeared to be was enzymatically controlled, the genetic control of ester synthesis was investigated. Lutein esterification was compared in a series of nullisomic-tetrasomic Chinese Spring lines and a Haruhikari (zero ester)//Sunco/Indis.82 (high ester) doubled haploid population. Lutein esterification was controlled by a locus, designated Lute, located on the short arm of chromosome 7D closely linked with the marker loci gwm295, wPt-1163 and wPt-3727. In addition to wheat, esterification in banana, Musa acuminata Colla cv Cavendish group was also investigated. Compared to wheat, different patterns of esterification were observed in banana during the ripening with ester synthesis occurring in both banana peel and flesh during post harvest ripening. Esterification in banana occurred under higher moisture content than in wheat and offers another tissue model for the study of the esterification mechanism. This thesis contributes valuable new information on the formation and genetic control of lutein ester formation in wheat grain and will be of value to manufacturers of wheat products seeking to retain lutein in end-products for delivery to costumers.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2013

Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library.
Langdon 7D(7A) and 7D(7B) durum substitution lines were crossed with DBA-Aurora durum wheat to introgress a lutein esterification gene,TaGelp1, from chromosome 7D onto its homoeologues 7A and 7B. Genotyping-by-sequencing based on DNA samples from durum wheat and bread wheat revealed single nucleotide polymorphism (SNPs) among the group-7 chromosomes. Sixteen KASP markers were developed and to be able to differentiate among these chromosomes. Nine 7A-7D markers were used to characterise progeny populations to search for dissociation of molecular markers which may indicate chromosomal recombination. Evidence of possible 7A-7D recombination was found in a small number of progeny (less than 4%). Most of the putative marker dissociations were in the centromeric region but one plant was found to carry only a small distal fragment of 7DS including TaGelp1. The findings suggest crossing normal durum with Langdon 7D(7A) combined with KASP marker assistance can be applied as a method to introgress and assess genes from chromosome 7D onto its homoeologues without resorting to use of wheat with the Ph1 deletion.
Thesis (M.Bio.(PB)) -- University of Adelaide, Masters of Biotechnology (Plant Biotechnology), School of Agriculture, Food and Wine, 2016.