Genetic Analysis of Genes for Yellow Pigment Content …
Phytoene synthase (Psy) gene is a critical gene influencing biosynthetic pathway of yellow pigment (YP) in bread wheat.
(1997) Genetic analysis of chlorophyll biosynthesis ..
Many studies have demonstrated the effects of mutations in anthocyanin structural or regulatory genes on anthocyanin pigmentation. Loss-of-function mutations in , , , , and normally cause a block in the biosynthesis, and plants harboring these mutations often produce white flowers or are colorless in tissues that usually contain color pigments (; ; ; ; ). Studies of several yellow-flowered varieties of ornamental plants including and showed that recessive mutations in caused the accumulation of naringenin chalcone, resulting in yellow flowers (; ). However, in some cases, mutations did not result in complete disruption of anthocyanin production because some portion of the CHI substrate, naringenin chalcone, could be spontaneously catalyzed and proceed into the pathway (; ). Mutations in either or in many cases caused color alterations. Studies in roses, and demonstrated that the lack of blue-purple in these plants was due to the loss of , which encodes the key enzyme responsible for delphinidin synthesis (). F3'H switches anthocyanin biosynthesis to red-colored cyanidins and, in some varieties of in which is mutated, anthocyanin biosynthesis proceeds towards pelargonidin production resulting in orange flowers (). Furthermore, certain types of mutation in led to alterations in enzyme specificity towards its substrates. For example, while DFRs from many species such as and have broad specificity to the three types of dihydroflavonol, DFRs from petunia and cannot reduce dihydrokaempferol efficiently and, therefore, cannot produce pelargonidin-based color pigments (; ; ; ).
Understanding the control of anthocyanin biosynthesis is beneficial to genetic improvement for floral production in orchids. Full-length cDNA of , , , , , , , and was isolated from hybrids with purple, peach, white and greenish white flowers. Analysis of the deduced amino acid sequences and gene expression levels of the eight genes suggested potential causes of color variation among the hybrids. Peach hybrid (SC) was likely due to changes in anthocyanin production from cyanidin to pelargonidin through mutations in , and the low color intensity was likely derived from the low expression levels of and . In addition, white hybrid (RW) was likely caused by several mutations in and/or high expression levels of , an enzyme that converts color flavonoid intermediates into colorless flavonols. Simultaneous loss of , , and expression observed in another white hybrid (JW) indicated that an alteration of anthocyanin regulatory controls was likely the cause of white coloration. Furthermore, analysis of hybrid mutants bearing pale and dark flowers demonstrated the influence of the expression of anthocyanin genes on the intensity of flower colors. Data obtained from this work could contribute to new strategies for future orchid breeding.
Vitiligo: Practice Essentials, Background, Pathophysiology
We found that YY-1 generated the greatest pigment yields when grown in rice medium compared to liquid mediums with other carbon sources, such as malt medium, potato/dextrose medium or sucrose–yeast extract medium (). Through experiments using different carbon sources for YY-1, we further confirmed that the pigment yields are significantly increased when rice is used as the sole carbon source in comparison with other carbon sources, such as glucose and sucrose (). These findings are consistent with previous reports that different carbon sources can regulate the biosynthesis of secondary metabolism products,. Additionally, we found that during the course of fermentation of YY-1 in rice medium, the biomass increased rapidly in the early logarithmic growth phase (around the fourth day), whereas the pigment value increased rapidly in the late logarithmic growth phase (around the eighth day) (); such phenomena have also been reported for other pigment-yielding strains. To investigate the mechanism underlying the high pigment yields during the late logarithmic growth phase in rice medium, transcriptome comparisons were performed for YY-1 grown using different carbon source media (rice medium vs. sucrose–yeast extract medium) and between YY-1 grown for four or eight days in rice medium.
Several novel enzymes involved in pigment synthesis were found in our study. Balakrishnan et al. previously suggested that the FAS gene pair (MpFasA and MpFasB) might be responsible for the biosynthesis of 3-oxoacyl-thioester, which is an intermediate in pigment synthesis; however, no canonical FAS with a similar function has been reported. Other reports suggested that the formation of the condensation product is likely catalyzed by a PKS. We suggest that C5.137 might act as a dual-functioning PKS or that another PKS gene is responsible for the synthesis of 3-oxoacyl-thioester from acyl-thioester. In YY-1, we found another PKS gene cluster (C2.18–C2.32) that may also be related to pigment synthesis. A nonreducing polyketide synthase (NR-PKS) gene (C2.25) in this cluster exhibits a close relationship with four reported pigment biosynthesis genes,,,. Moreover, this NR-PKS shares 54% similarity with a red pigment biosynthesis gene (AAS48892) obtained by complementing an albino mutant in Nectria haematococca (). Transcriptome analysis indicated that except for the C5.137 and citrinin PKS C6.123 genes, C2.25 exhibits the highest expression level among PKS genes under high pigment production conditions. We proposed that C2.25 catalyzes the conversion from acyl-thioester to 3-oxoacyl-thioester. Additionally, C2.24 was proposed to be involved in the dehydration reaction of certain steps in pigment biosynthesis (). The oxidoreductases (C5.130, C5.135, C1.1074, C6.152 and C7.13) are proposed to reduce the resultant intermediate 11 in the presence of NADPH.
It is related to both genetic and nongenetic factors
Anthocyanins are a group of flavonoid glycosides constituting the major color pigments in flowers and fruit. Anthocyanins are synthesized along with flavonoid biosynthesis through a series of enzymatic reactions that convert chalcone into three major anthocyanidin types: cyanidin (red to magenta), pelargonidin (brick red to scarlet) and delphinidin (purple to violet) (see , for reviews). Structural and regulatory genes are the key controls for the biosynthesis process. Spatial and temporal expression of the structural genes regulated through regulatory proteins dictates the production of anthocyanins in plants ().
A PKS-FAS gene cluster homologous to that in M. pilosus was identified in YY-1. The transcriptome analysis (see below) indicated that under high pigment production conditions, most genes in this PKS-FAS cluster, especially the PKS gene (C5.137), are expressed at high levels ( and ), which further supports the key role of this gene cluster in pigment synthesis. The PKS-FAS gene cluster in YY-1 is somewhat smaller than that in M. pilosus (), and some genes with unclear function (for instance, 2373-2379 in M. pilosus) are absent in YY-1, indicating they are not required for pigment synthesis. The genes between the PKS and FAS genes, which may be the core genes for pigment synthesis, show high conservation. Based on gene function prediction and transcriptomic data, we generated a comprehensive proposal for the biosynthesis pathway of Monascus pigment (), which provides a strong foundation for the future identification, utilization and modification of relevant enzymes in industry.
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Age-Related Macular Degeneration — NEJM
Reddy (2008) Genetic and molecular analysis of the anthocyanin pigmentation pathway in rice
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Genes involved in the biosynthesis of a fluorescent pigment by Pseudomonas syringae pv
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Anthocyanin - Wikipedia
Metabolism – Proteins | Biochemistry for Medics – …
The expression analysis showed that, in colored-flower hybrids including SE and SC, , , , , and were generally expressed from young bud to mature bud stages. These expression data match with the flower colors as these five genes have been reported to be the key genes responsible for anthocyanin production (). In all four hybrids, while the expression of the eight genes mostly occurred at the young and mature bud stages and dramatically declined to very low levels at the anthesis stage, the expression of was observed at elevated levels in the progression towards the anthesis stage. Despite the presence and expression of the gene, delphinidins have never been found to be the color pigments of species, and myricetin and syringetin 3',5'-hydroxylated flavonols were shown to represent F3'5'H enzymatic activity in (). Thus, our results suggest that the function of F3'5'H mostly occurs at late stages of flower development and this could contribute to the production of 3',5'-hydroxylated flavonols, which act as co-pigments for coloration in flowers.
CLAMS HC Comprehensive Lab Animal Monitoring System …
We explored further the causes of the color changes in SE by examining two SE mutants that exhibit flowers with a paler color (L, ER6-329) and a darker color (D, ER5-1129) using sequence and expression analyses. Analysis of nucleotide sequences from eight anthocyanin biosynthesis genes showed no point mutation in both L and D mutants (data not shown). Semi-quantitative RT-PCR of , , , , and showed that, while the expression levels of the five genes in the wild type and the D mutant were similar, the expression levels in the L mutant were generally lower than those in both the wild type and the D mutant (). This indicated that the paler-colored flowers in the L mutant were the result of simultaneous reductions of gene expression in at least five genes involved in anthocyanin biosynthesis.
Genomic and Epigenomic Landscapes of Adult De …
Despite its white flowers, the expression profiles of the eight genes in the RW hybrid were similar and even higher for , , and than those in the SC hybrid. Two notable features were that the expression level of was about 5-fold higher than those from the other hybrids and there was likely to be an interplay between the expression of and . On the basis of our results, the production of white flowers in the RW hybrid could possibly be explained by either or both of the following causes. First, 6 amino acid alterations in the conserved regions of F3H of the RW hybrid compared with those of the SE hybrid suggest a high potential for F3H functional alteration. This could result in the blockage of subsequent anthocyanin biosynthesis and the loss of color pigments (). Second, FLS catalyzes the production of colorless flavonols and competes with DFR in terms of anthocyanin production. Previous studies in white-flowered petunia containing high levels of flavonols demonstrated that the flower color could change from white to pink when either was down-regulated or was overexpressed (). Giving that the CHI2 function was disrupted by premature termination and expression was very low at early floral developmental stages, the level of the catalytic product of CHI could be very low in RW floral tissues. Thus, the white flowers of the RW hybrid could be the result of low expression levels of and high expression levels of , which cause the conversion of color flavonoid intermediates into colorless flavonols. To rule out these possibilities, further study of anthocyanin and flavonol compositions in RW flowers is required. If the RW hybrid exhibited white flowers because of CHI and/or F3H deficiencies, the accumulation of both anthocyanins and flavonols should be greatly reduced, whereas if this white flower phenotype is caused by the up-regulation of , the accumulation of flavonols should be increased and that of anthocyanins should be reduced.
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