scholarly journals A Tetratricopeptide Repeat Protein Regulates Carotenoid Biosynthesis and Chromoplast Development in Monkeyflowers (Mimulus)

2017 ◽  
Author(s):  
Lauren E. Stanley ◽  
Baoqing Ding ◽  
Wei Sun ◽  
Fengjuan Mou ◽  
Connor Hill ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Anthocyanin Biosynthesis ◽  
Carotenoid Biosynthesis ◽  
Chemical Mutagenesis ◽  
Developmental Genetics ◽  
Tetratricopeptide Repeat ◽  
Loss Of Function ◽  
In Planta ◽  
Biosynthetic Genes ◽  
Carotenoid Biosynthetic Pathway

ABSTRACTThe incredible diversity of floral color and pattern in nature is largely determined by the transcriptional regulation of anthocyanin and carotenoid biosynthetic genes. While the transcriptional control of anthocyanin biosynthesis is well understood, little is known about the factors regulating the carotenoid biosynthetic pathway in flowers. Here, we characterize the Reduced Carotenoid Pigmentation 2 (RCP2) locus from two monkeyflower (Mimulus) species, the bumblebee-pollinated M. lewisii and hummingbird-pollinated M. verbenaceus. We show that loss-of-function mutations of RCP2 cause drastic down-regulation of the entire carotenoid biosynthetic pathway in these species. Through bulk segregant analysis and transgenic experiments, we have identified the causal gene underlying RCP2, encoding a tetratricopeptide repeat (TPR) protein that is closely related to the Arabidopsis Reduced Chloroplast Coverage (REC) proteins. RCP2 appears to regulate carotenoid biosynthesis independently of RCP1, a previously identified R2R3-MYB master regulator of carotenoid biosynthesis. We show that RCP2 is required for chromoplast development and suggest that it most likely regulates the expression of carotenoid biosynthetic genes through chromoplast-to-nucleus retrograde signaling. Furthermore, we demonstrate that M. verbenaceus is just as amenable to chemical mutagenesis and in planta transformation as the more extensively studied M. lewisii, making these two species an excellent platform for comparative developmental genetics studies of two closely related species with dramatic phenotypic divergence.

scholarly journals Pathway Evolution by Horizontal Transfer and Positive Selection Is Accommodated by Relaxed Negative Selection upon Upstream Pathway Genes in Purple Bacterial Carotenoid Biosynthesis

2009 ◽  
Vol 191 (24) ◽  
pp. 7500-7508 ◽  
Author(s):  
Jonathan L. Klassen
Keyword(s):  
Positive Selection ◽  
Horizontal Transfer ◽  
Negative Selection ◽  
Biosynthetic Pathway ◽  
Carotenoid Biosynthesis ◽  
Biochemical Network ◽  
Biosynthetic Genes ◽  
Substrate Specificities ◽  
Functional Changes ◽  
Synonymous Mutations

ABSTRACT Horizontal gene transfer and selection are major forces driving microbial evolution. However, interactions between them are rarely studied. Phylogenetic analyses of purple bacterial carotenoid biosynthesis genes suggest two lineages: one producing spheroidenone and the other producing spirilloxanthin. Of the latter lineage, Rubrivivax gelatinosus S1 and Hoeflea phototrophica DFL-43 also or instead produce spheroidenone. Evolution of the spheroidenone pathway from that producing spirilloxanthin theoretically requires changes in the substrate specificity of upstream pathway enzymes and acquisition of a terminal ketolase (CrtA). In R. gelatinosus and likely also in H. phototrophica, CrtA was acquired from the Bacteroidetes, in which it functions as a hydroxylase. Estimation of nonsynonymous and synonymous mutations using several pairwise methods indicated positive selection upon both genes, consistent with their functional changes from hydroxylases to ketolases. Relaxed negative selection upon all other carotenoid biosynthetic genes in these organisms was also apparent, likely facilitating changes in their substrate specificities. Furthermore, all genes responsible for terminal carotenoid biosynthetic pathway steps were under reduced negative selection compared to those known to govern biosynthetic pathway specificity. Horizontal transfer of crtA into R. gelatinosus and H. phototrophica has therefore likely been promoted by (i) the apparent selective advantage of spheroidenone production relative to spirilloxanthin production, (ii) reduced negative selection upon other carotenoid biosynthetic genes, facilitating changes in their substrate specificities, and (iii) preexisting low enzyme substrate specificities due to relaxed negative selection. These results highlight the importance and complexity of selection acting upon both a horizontally transferred gene and the biochemical network into which it is integrating.

The 'squalene route' to carotenoid biosynthesis is widespread in Bacteria.

2021 ◽  
Author(s):  
Carlos Santana-Molina ◽  
Valentina Henriques ◽  
Damaso Hornero-Méndez ◽  
Damien P. Devos ◽  
Elena Rivas-Marin
Keyword(s):  
Biosynthetic Pathway ◽  
Carotenoid Biosynthesis ◽  
Stress Conditions ◽  
Widespread Occurrence ◽  
Functional Roles ◽  
Evolutionary Scenario ◽  
Carotenoid Biosynthetic Pathway ◽  
Potential Origin

Squalene is mostly associated with the biosynthesis of polycyclic triterpenes. Although there have been suggestions that squalene could be involved in the biosynthesis of carotenoids, functionally and evolutionarily related to polycyclic triterpenes, evidence of this 'squalene route' in nature was lacking. We demonstrate that planctomycetes synthesize C30 carotenoids via squalene and that this 'squalene route' is widely distributed in Bacteria. We also investigated the functional roles of hopanoids and carotenoids in Planctomycetes and show that their protective functions under stress conditions are complementary. Our evolutionary analyses suggest that the C30 carotenoid biosynthetic pathway is the most ancestral, with a potential origin in Firmicutes or Planctomycetes . In addition, we propose an evolutionary scenario to explain the diversification of the different carotenoid and squalene pathways. Together, these results improve the evolutionary contextualization of these molecules. Likewise, the widespread occurrence of the squalene route in bacteria increases the functional repertoire of squalene.

scholarly journals Chemical inhibition of lycopene β-cyclases unmask operation of phytoene synthase 2 in ripening tomato fruits

2021 ◽  
Author(s):  
Prateek Gupta ◽  
Marta Rodriguez-Franco ◽  
Reddaiah Bodanapu ◽  
Yellamaraju Sreelakshmi ◽  
Rameshwar Sharma
Keyword(s):  
Biosynthetic Pathway ◽  
Carotenoid Biosynthesis ◽  
Phytoene Synthase ◽  
Triethylamine Hydrochloride ◽  
Knockout Mutant ◽  
Tomato Fruits ◽  
Chemical Inhibition ◽  
Specific Pathway ◽  
Carotenoid Biosynthetic Pathway

In ripening tomato fruits, the leaf-specific carotenoids biosynthesis mediated by phytoene synthase 2 (PSY2) is replaced by a fruit-specific pathway by the expression of two chromoplast-specific genes: phytoene synthase 1 (PSY1) and lycopene-β-cyclase (CYCB). Consequently, mutations in those two and other genes contributing to intermediate steps render the ripened tomato fruits bereft of lycopene. To decipher whether PSY2-mediated pathway also operates in ripening fruits, we blocked the in vivo activity of lycopene-β-cyclases by injecting CPTA (2-(4-Chlorophenylthio) triethylamine hydrochloride), an inhibitor of lycopene-β-cyclases. The injection of CPTA induced accumulation of lycopene in leaves, immature-green and ripening fruits. Even, in tomato mutants deficient in fruit-specific carotenoid biosynthesis such as V7 and r (PSY1), and ζ-carotene isomerase (ZISO), CPTA triggered lycopene accumulation. The CPTA-treated ziso mutant fruits, where PSY1 remains functional, accumulated phytoene and phytofluene. Conversely, CPTA-treated PSY1-knockout mutant (r3756) fruits did not accumulate phytoene and phytofluene. CPTA-treated fruits were enriched in lycopene-derived volatiles and had reduced ABA levels. The lycopene accumulation was associated with the partial transformation of chloroplasts to chromoplasts bearing thread-like crystalline structures, indicating lycopene accumulation. Our study shows that inhibition of lycopene β-cyclases unmasks the operation of a parallel carotenoid biosynthetic pathway mediated by PSY2 in ripening tomato fruits.

scholarly journals GFAT2 and AMDHD2 act in tandem to control the hexosamine biosynthetic pathway

2021 ◽  
Author(s):  
Virginia Kroef ◽  
Sabine Ruegenberg ◽  
Moritz Horn ◽  
Kira Allmeroth ◽  
Lena Ebert ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Biosynthetic Pathway ◽  
Embryonic Stem ◽  
Chemical Mutagenesis ◽  
Lower Sensitivity ◽  
Loss Of Function ◽  
Critical Function ◽  
Hexosamine Biosynthetic Pathway ◽  
Rate Limiting

AbstractThe hexosamine biosynthetic pathway (HBP) produces the essential metabolite UDP-GlcNAc and plays a key role in metabolism, cancer, and aging. The HBP is controlled by its rate-limiting enzyme glutamine fructose-6-phosphate amidotransferase (GFAT) that is directly inhibited by UDP-GlcNAc in a feedback loop. HBP regulation by GFAT is well studied but other HBP regulators have remained obscure. Elevated UDP-GlcNAc levels counteract the glycosylation toxin tunicamycin (TM) and thus we screened for TM resistance in haploid mouse embryonic stem cells (mESCs) using random chemical mutagenesis to pinpoint new HBP regulators. We identified the N-acetylglucosamine deacetylase AMDHD2 that catalyzes a reverse reaction in the HBP and its loss strongly elevated UDP-GlcNAc. To better understand AMDHD2, we solved the crystal structure and found that loss-of-function is caused by protein destabilization or interference with its catalytic activity. Finally, we show that mESCs express AMDHD2 together with GFAT2 instead of the more common paralog GFAT1. Compared with GFAT1, GFAT2 had a much lower sensitivity to UDP-GlcNAc inhibition, explaining how AMDHD2 loss-of-function resulted in HBP activation. This HBP configuration in which AMDHD2 serves to balance GFAT2 activity was also observed in other mESCs and, consistently, the GFAT2/GFAT1 ratio decreased with differentiation of mouse and human embryonic stem cells. Together, our data reveal a critical function of AMDHD2 in limiting UDP-GlcNAc production in cells that use GFAT2 for metabolite entry into the HBP.

scholarly journals Impact of Environmental Factors on Stilbene Biosynthesis

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 90
Author(s):  
Alessio Valletta ◽  
Lorenzo Maria Iozia ◽  
Francesca Leonelli
Keyword(s):  
Environmental Factors ◽  
Biosynthetic Pathway ◽  
In Planta ◽  
Organ Cultures ◽  
Related Plant ◽  
Valuable Compounds ◽  
Stilbene Compounds ◽  
Stilbene Biosynthesis ◽  
Abiotic Environmental Factors

Stilbenes are a small family of polyphenolic secondary metabolites that can be found in several distantly related plant species. These compounds act as phytoalexins, playing a crucial role in plant defense against phytopathogens, as well as being involved in the adaptation of plants to abiotic environmental factors. Among stilbenes, trans-resveratrol is certainly the most popular and extensively studied for its health properties. In recent years, an increasing number of stilbene compounds were subjected to investigations concerning their bioactivity. This review presents the most updated knowledge of the stilbene biosynthetic pathway, also focusing on the role of several environmental factors in eliciting stilbenes biosynthesis. The effects of ultraviolet radiation, visible light, ultrasonication, mechanical stress, salt stress, drought, temperature, ozone, and biotic stress are reviewed in the context of enhancing stilbene biosynthesis, both in planta and in plant cell and organ cultures. This knowledge may shed some light on stilbene biological roles and represents a useful tool to increase the accumulation of these valuable compounds.

scholarly journals Frequent gain- and loss-of-function mutations of the BjMYB113 gene accounted for leaf color variation in Brassica juncea

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Guanghui An ◽  
Jiongjiong Chen
Keyword(s):  
Brassica Juncea ◽  
Anthocyanin Biosynthesis ◽  
Color Variation ◽  
Nucleotide Polymorphisms ◽  
Loss Of Function ◽  
High Accumulation ◽  
Single Nucleotide ◽  
Breeding Programs ◽  
Promoter Sequences ◽  
Expression Of Genes

Abstract Background Mustard (Brassica juncea) is an important economic vegetable, and some cultivars have purple leaves and accumulate more anthocyanins than the green. The genetic and evolution of purple trait in mustard has not been well studied. Result In this study, free-hand sections and metabolomics showed that the purple leaves of mustard accumulated more anthocyanins than green ones. The gene controlling purple leaves in mustard, Mustard Purple Leaves (MPL), was genetically mapped and a MYB113-like homolog was identified as the candidate gene. We identified three alleles of the MYB113-like gene, BjMYB113a from a purple cultivar, BjMYB113b and BjMYB113c from green cultivars. A total of 45 single nucleotide polymorphisms (SNPs) and 8 InDels were found between the promoter sequences of the purple allele BjMYB113a and the green allele BjMYB113b. On the other hand, the only sequence variation between the purple allele BjMYB113a and the green allele BjMYB113c is an insertion of 1,033-bp fragment in the 3’region of BjMYB113c. Transgenic assay and promoter activity studies showed that the polymorphism in the promoter region was responsible for the up-regulation of the purple allele BjMYB113a and high accumulation of anthocyanin in the purple cultivar. The up-regulation of BjMYB113a increased the expression of genes in the anthocyanin biosynthesis pathway including BjCHS, BjF3H, BjF3’H, BjDFR, BjANS and BjUGFT, and consequently led to high accumulation of anthocyanin. However, the up-regulation of BjMYB113 was compromised by the insertion of 1,033-bp in 3’region of the allele BjMYB113c. Conclusions Our results contribute to a better understanding of the genetics and evolution of the BjMYB113 gene controlling purple leaves and provide useful information for further breeding programs of mustard.

scholarly journals A combinatorial action of GmMYB176 and GmbZIP5 controls isoflavonoid biosynthesis in soybean (Glycine max)

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Arun Kumaran Anguraj Vadivel ◽  
Tim McDowell ◽  
Justin B. Renaud ◽  
Sangeeta Dhaubhadel
Keyword(s):  
Transcription Factor ◽  
Hairy Roots ◽  
Defense Mechanisms ◽  
Biosynthetic Pathway ◽  
Bzip Transcription Factor ◽  
Myb Transcription Factor ◽  
In Planta ◽  
Rnai Silencing ◽  
Protein Protein Interaction ◽  
Soybean Roots

AbstractGmMYB176 is an R1 MYB transcription factor that regulates multiple genes in the isoflavonoid biosynthetic pathway, thereby affecting their levels in soybean roots. While GmMYB176 is important for isoflavonoid synthesis, it is not sufficient for the function and requires additional cofactor(s). The aim of this study was to identify the GmMYB176 interactome for the regulation of isoflavonoid biosynthesis in soybean. Here, we demonstrate that a bZIP transcription factor GmbZIP5 co-immunoprecipitates with GmMYB176 and shows protein–protein interaction in planta. RNAi silencing of GmbZIP5 reduced the isoflavonoid level in soybean hairy roots. Furthermore, co-overexpression of GmMYB176 and GmbZIP5 enhanced the level of multiple isoflavonoid phytoallexins including glyceollin, isowighteone and a unique O-methylhydroxy isoflavone in soybean hairy roots. These findings could be utilized to develop biotechnological strategies to manipulate the metabolite levels either to enhance plant defense mechanisms or for human health benefits in soybean or other economically important crops.

scholarly journals The MIR-Domain of PbbHLH2 Is Involved in Regulation of the Anthocyanin Biosynthetic Pathway in ”Red Zaosu” (PyrusBretschneideri Rehd.) Pear Fruit

2021 ◽  
Vol 22 (6) ◽  
pp. 3026
Author(s):  
Xieyu Li ◽  
Fangxin Xiang ◽  
Wei Han ◽  
Bingqing Qie ◽  
Rui Zhai ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Anthocyanin Biosynthesis ◽  
Bimolecular Fluorescence Complementation ◽  
Anthocyanin Content ◽  
Pear Fruit ◽  
Fruit Peel ◽  
Interaction Domain ◽  
Dihydroflavonol Reductase ◽  
Anthocyanin Biosynthetic Pathway ◽  
R2r3 Myb

The N-terminal of Myc-like basic helix-loop-helix transcription factors (bHLH TFs) contains an interaction domain, namely the MYB-interacting region (MIR), which interacts with the R2R3-MYB proteins to regulate genes involved in the anthocyanin biosynthetic pathway. However, the functions of MIR-domain bHLHs in this pathway are not fully understood. In this study, PbbHLH2 containing the MIR-domain was identified and its function investigated. The overexpression of PbbHLH2 in ”Zaosu” pear peel increased the anthocyanin content and the expression levels of late biosynthetic genes. Bimolecular fluorescence complementation showed that PbbHLH2 interacted with R2R3-MYB TFs PbMYB9, 10, and 10b in onion epidermal cells and confirmed that MIR-domain plays important roles in the interaction between the MIR-domain bHLH and R2R3-MYB TFs. Moreover, PbbHLH2 bound and activated the dihydroflavonol reductase promoter in yeast one-hybrid (Y1H) and dual-luciferase assays. Taken together these results suggested that the MIR domain of PbbHLH2 regulated anthocyanin biosynthesis in pear fruit peel.

scholarly journals Genetic Characterization of the Carotenoid Biosynthetic Pathway in Methylobacterium extorquens AM1 and Isolation of a Colorless Mutant

2003 ◽  
Vol 69 (12) ◽  
pp. 7563-7566 ◽  
Author(s):  
Stephen J. Van Dien ◽  
Christopher J. Marx ◽  
Brooke N. O'Brien ◽  
Mary E. Lidstrom
Keyword(s):  
Biosynthetic Pathway ◽  
Genetic Characterization ◽  
Carotenoid Biosynthesis ◽  
Biosynthesis Pathway ◽  
Wild Type ◽  
Methylobacterium Extorquens ◽  
Growth Properties ◽  
Carotenoid Biosynthesis Pathway ◽  
Free Strain

ABSTRACT Genomic searches were used to reconstruct the putative carotenoid biosynthesis pathway in the pink-pigmented facultative methylotroph Methylobacterium extorquens AM1. Four genes for putative phytoene desaturases were identified. A colorless mutant was obtained by transposon mutagenesis, and the insertion was shown to be in one of the putative phytoene desaturase genes. Mutations in the other three did not affect color. The tetracycline marker was removed from the original transposon mutant, resulting in a pigment-free strain with wild-type growth properties useful as a tool for future experiments.

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