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Surinder Chopra - One of the best experts on this subject based on the ideXlab platform.
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Maize Flavan-4-ols and Anthocyanins Alleviated Dextran Sulfate Sodium-Induced Colitis in Mice via Intestinal Barrier Function Restoration
Current Developments in Nutrition, 2020Co-Authors: Binning Wu, Surinder Chopra, Shiyu Li, Haotian Chang, Ruth Anderson, Lavanya ReddivariAbstract:Abstract Objectives This study investigated the anti-inflammatory effects of anthocyanins and flavan-4-ols (precursor of Phlobaphenes) within a whole-food matrix against dextran sulfate sodium (DSS)-induced colitis using four maize near-isogenic lines (NILs) that differ only in a single class of flavonoids. The four NILs are A (lacks anthocyanins and Phlobaphenes), B (Phlobaphenes +), C (anthocyanins +) and D (anthocyanins + and Phlobaphenes +). Methods Conventional male C57BL6 mice were subjected to control diet 25% A, B, C, and D supplemented corn diet. Germ-free (GF) C57BL6 mice were subjected to either control or 25% D supplemented diet. Colitis was induced in both conventional and GF mice by 3% and 1.25% (w/v) DSS in the drinking water, respectively. Intestinal permeability was measured using FITC-dextran. RT-PCR was used to analyze the gene expression levels and 16S rRNA for bacterial relative abundance. Results In conventional mice, supplementation of A, B, C, and D prevented DSS-induced colon shortening and body weight loss compared to mice on the control diet (P < 0.05). Mice supplemented with B, C, D diets had lower gut permeability than DSS mice (P < 0.05). The mRNA expression level of pro-inflammatory interleukin-6 (IL-6) was suppressed in B, C and D supplemented mice whereas, interleukin 1β (IL-1β) expression was lowered in mice supplemented with C and D diets only. Supplementation of the four NILs decreased the abundance of the genus Pseudomonas in colitic mice (P < 0.05). In GF mice, D diet ameliorated DSS-induced colon shortening and elevated gut permeability. The expression level of IL-6 and IL-1β were downregulated in GF mice fed with D diet (P < 0.05). Conclusions In summary, flavan-4-ols and/or anthocyanins in the whole-food matrix exerted their protective effects against DSS-induced chronic inflammation and concommitantly restored intestinal barrier function. GF mice experiment results demonstrated that above mentioned beneficial effects from bioactive corn compounds were partially independent of gut microbiota. Funding Sources USDA-NIFA awards 2016-67,017-29,285 and 2019-67,017-29,258.
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Comparative proteomics analysis by DIGE and iTRAQ provides insight into the regulation of phenylpropanoids in maize.
Journal of Proteomics, 2013Co-Authors: Michael L. Robbins, Iffa Gaffoor, Rajandeep S. Sekhon, Po-hao Wang, Marcia M. De O. Buanafina, Jai S. Rohila, Surinder ChopraAbstract:Abstract The maize pericarp color1 ( p1 ) gene encodes a Myb transcription factor that regulates the accumulation of 3-deoxyflavonoid pigments called Phlobaphenes. The Unstable factor for orange1 ( Ufo1 ) is a dominant epigenetic modifier of the p1 that results in ectopic pigmentation in pericarp. Presence of Ufo1-1 correlates with pleiotropic growth and developmental defects. To investigate the Ufo1-1 -induced changes in the proteome, we conducted comparative proteomics analysis of P1-wr; Ufo1-1 pericarps using the 2-D DIGE and iTRAQ techniques. Most of the identified proteins were found to be involved in glycolysis, protein synthesis and modification, flavonoid and lignin biosynthesis and defense responses. Further, immunoblot analysis of internode protein extracts demonstrated that caffeoyl CoA O-methyltransferase (COMT) is post-transcriptionally down regulated in P1-wr; Ufo1-1 plants. Consistent with the down regulation of COMT, the concentrations of p -coumaric acid, syringaldehydes, and lignin are reduced in P1-wr ; Ufo1-1 internodes. The reductions in these phenylpropanoids correlate with the bent stalk and stunted growth of P1-wr ; Ufo1-1 plants. Finally, over-expression of the p1 in transgenic plants is also correlated with a lodging phenotype and reduced COMT expression. We conclude that ectopic expression of p1 can result in developmental defects that are correlated with altered regulation and synthesis of phenylpropanoid compounds including lignin. Biological significance Transcription factors have specific expression patterns that ensure that the biochemical pathways under their control are active in relevant tissues. Plant breeders can select for alleles of transcription factors that produce desirable expression patterns to improve a plant's growth, development, and defense against insects and pathogens. The resulting de novo accumulation of metabolites in plant tissues in significant quantities could have beneficial and/or detrimental consequences. To understand this problem we investigated how the aberrant expression of a classically-studied transcription factor pericarp color1 ( p1 ) which regulates phenylpropanoid metabolism, affects the maize proteome in pericarp tissue. We utilized a dominant mutant Unstable factor for orange 1-1 ( Ufo1-1 ) which reduces the epigenetic suppression of p1 in various tissues throughout the maize plant. Our proteomic analysis shows how, in the presence of Ufo1-1 , key enzymes of the glycolytic and shikimic acid pathways were modulated to produce substrates required for flavonoid synthesis. The finding that the presence of Ufo1-1 affected the expression levels of various enzymes in the lignin pathway was of particular interest. We show that lignin was reduced in Ufo1-1 plants expressing p1 and was associated with the post-transcriptional down regulation of CoA O-methyltransferase (COMT) enzyme. We further correlated the down-regulation of COMT with plant bending phenotype in Ufo1-1 plants expressing p1 and to a stalk lodging phenotype of transgenic p1 plants. This study demonstrates that although there can be adverse consequences to aberrantly overexpressing transcription factors, there might also be benefits such as being able to reduce lignin content for biofuel crops. However, more research will be required to understand the genetic and epigenetic regulation of transcription factors and how their expression can be optimized to obtain desired traits in preferred tissue types. This article is part of a Special Issue entitled: Translational Plant Proteomics.
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Expression of flavonoid 3'-hydroxylase is controlled by P1, the regulator of 3-deoxyflavonoid biosynthesis in maize.
BMC Plant Biology, 2012Co-Authors: Mandeep Sharma, Erich Grotewold, Chenglin Chai, Kengo Morohashi, Maurice E. Snook, Surinder ChopraAbstract:Background: The maize (Zea mays) red aleurone1 (pr1) encodes a CYP450-dependent flavonoid 3’-hydroxylase (ZmF3’H1) required for the biosynthesis of purple and red anthocyanin pigments. We previously showed that Zmf3’h1 is regulated by C1 (Colorless1) and R1 (Red1) transcription factors. The current study demonstrates that, in addition to its role in anthocyanin biosynthesis, the Zmf3’h1 gene also participates in the biosynthesis of 3-deoxyflavonoids and Phlobaphenes that accumulate in maize pericarps, cob glumes, and silks. Biosynthesis of 3-deoxyflavonoids is regulated by P1 (Pericarp color1) and is independent from the action of C1 and R1 transcription factors. Results: In maize, apiforol and luteoforol are the precursors of condensed Phlobaphenes. Maize lines with functional alleles of pr1 and p1 (Pr1;P1) accumulate luteoforol, while null pr1 lines with a functional or non-functional p1 allele (pr1;P1 or pr1;p1) accumulate apiforol. Apiforol lacks a hydroxyl group at the 3’-position of the flavylium B-ring, while luteoforol has this hydroxyl group. Our biochemical analysis of accumulated compounds in different pr1 genotypes showed that the pr1 encoded ZmF3’H1 has a role in the conversion of mono-hydroxylated to bi-hydroxylated compounds in the B-ring. Steady state RNA analyses demonstrated that Zmf3’h1 mRNA accumulation requires a functional p1 allele. Using a combination of EMSA and ChIP experiments, we established that the Zmf3’h1 gene is a direct target of P1. Highlighting the significance of the Zmf3’h1 gene for resistance against biotic stress, we also show here that the p1 controlled 3-deoxyanthocyanidin and C-glycosyl flavone (maysin) defence compounds accumulate at significantly higher levels in Pr1 silks as compared to pr1 silks. By virtue of increased maysin synthesis in Pr1 plants, corn ear worm larvae fed on Pr1; P1 silks showed slower growth as compared to pr1; P1 silks. Conclusions: Our results show that the Zmf3’h1 gene participates in the biosynthesis of Phlobaphenes and agronomically important 3-deoxyflavonoid compounds under the regulatory control of P1.
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Tissue Culture-induced Novel Epialleles of a Myb Transcription Factor Encoded by pericarp color1 in Maize
Genetics, 2010Co-Authors: Yong Rhee, Surinder Chopra, Rajandeep S. Sekhon, Shawn M. KaepplerAbstract:Plants regenerated from tissue culture often display somaclonal variation, that is, somatic and often meiotically heritable phenotypic variation that can result from both genetic and epigenetic modifications. To better understand the molecular basis of somaclonal variation, we have characterized four unique tissue culture-derived epialleles of the pericarp color1 (p1) gene of maize (Zea mays L.). The progenitor p1 allele, P1-wr, is composed of multiple head-to-tail tandemly arranged copies of the complete gene unit and specifies brick-red Phlobaphene pigmentation in the cob glumes. The novel epialleles identified in progeny plants regenerated from tissue culture showed partial to complete loss of p1 function indicated by pink or colorless cob glumes. Loss of pigmentation was correlated with nearly complete loss of p1 steady-state transcripts. DNA gel-blot analysis and genomic bisulfite sequencing showed that silencing of the epialleles was associated with hypermethylation of a region in the second intron of P1-wr. Presence of Unstable factor for orange1 (Ufo1), an unlinked epigenetic modifier of p1, restored the cob glume pigmentation in the silenced alleles, and such reactivation was accompanied by hypomethylation of the p1 sequence. This observation confirmed that silencing of the epialleles is indeed due to epigenetic modifications and that the p1 epialleles were capable of functioning in the presence of the correct trans-acting factors. While the low-copy regions of the genome generally undergo hypomethylation during tissue culture, our study shows that the tandemly repeated genes are also prone to hypermethylation and epigenetic silencing.
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Flavonoid Phytoalexin Dependent Resistance to Anthracnose Leaf Blight Requires a Functional yellow seed1 in Sorghum bicolor
Genetics, 2010Co-Authors: Farag Ibraheem, Iffa Gaffoor, Surinder ChopraAbstract:In Sorghum bicolor, a group of phytoalexins are induced at the site of infection by Colletotrichum sublineolum, the anthracnose fungus. These compounds, classified as 3-deoxyanthocyanidins, have structural similarities to the precursors of Phlobaphenes. Sorghum yellow seed1 (y1) encodes a MYB transcription factor that regulates Phlobaphene biosynthesis. Using the candystripe1 transposon mutagenesis system in sorghum, we have isolated functional revertants as well as loss-of-function alleles of y1. These near-isogenic lines of sorghum show that, compared to functionally revertant alleles, loss of y1 lines do not accumulate Phlobaphenes. Molecular characterization of two null y1 alleles shows a partial internal deletion in the y1 sequence. These null alleles, designated as y1-ww1 and y1-ww4, do not accumulate 3-deoxyanthocyanidins when challenged with the nonpathogenic fungus Cochliobolus heterostrophus. Further, as compared to the wild-type allele, both y1-ww1 and y1-ww4 show greater susceptibility to the pathogenic fungus C. sublineolum. In fungal-inoculated wild-type seedlings, y1 and its target flavonoid structural genes are coordinately expressed. However, in y1-ww1 and y1-ww4 seedlings where y1 is not expressed, steady-state transcripts of its target genes could not be detected. Cosegregation analysis showed that the functional y1 gene is genetically linked with resistance to C. sublineolum. Overall results demonstrate that the accumulation of sorghum 3-deoxyanthocyanidin phytoalexins and resistance to C. sublineolum in sorghum require a functional y1 gene.
Thomas Peterson - One of the best experts on this subject based on the ideXlab platform.
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The maize unstable factor for orange1 is a dominant epigenetic modifier of a tissue specifically silent allele of pericarp color1.
Genetics, 2003Co-Authors: Surinder Chopra, Suzy M. Cocciolone, Shaun Bushman, Vineet Sangar, Michael D. Mcmullen, Thomas PetersonAbstract:We have characterized Unstable factor for orange1 (Ufo1), a dominant, allele-specific modifier of expression of the maize pericarp color1 (p1) gene. The p1 gene encodes an Myb-homologous transcriptional activator of genes required for biosynthesis of red Phlobaphene pigments. The P1-wr allele specifies colorless kernel pericarp and red cobs, whereas Ufo1 modifies P1-wr expression to confer pigmentation in kernel pericarp, as well as vegetative tissues, which normally do not accumulate significant amounts of Phlobaphene pigments. In the presence of Ufo1, P1-wr transcript levels and transcription rate are increased in kernel pericarp. The P1-wr allele contains approximately six p1 gene copies present in a hypermethylated and multicopy tandem array. In P1-wr Ufo1 plants, methylation of P1-wr DNA sequences is reduced, whereas the methylation state of other repetitive genomic sequences was not detectably affected. The phenotypes produced by the interaction of P1-wr and Ufo1 are unstable, exhibiting somatic mosaicism and variable penetrance. Moreover, the changes in P1-wr expression and methylation are not heritable: meiotic segregants that lack Ufo1 revert to the normal P1-wr expression and methylation patterns. These results demonstrate the existence of a class of modifiers of gene expression whose effects are associated with transient changes in DNA methylation of specific loci.
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excision of the candystripe1 transposon from a hyper mutable y1 cs allele shows that the sorghumy1 gene controls the biosynthesis of both 3 deoxyanthocyanidin phytoalexins and Phlobaphene pigments
Physiological and Molecular Plant Pathology, 2002Co-Authors: Surinder Chopra, Amanda J Gevens, Catherine Svabek, Karl V Wood, Thomas Peterson, Ralph L NicholsonAbstract:The 3-deoxyanthocyanidin phytoalexins produced in sorghum leaves in response to Colletotrichum sublineolum have chemical structure similarities to the 3-deoxy flavonoids that are precursors of Phlobaphene pigments. Phlobaphenes are commonly observed in the pericarp of mature sorghum grains, while synthesis of 3-deoxyanthocyanidin phytoalexins is a site-specific response to infection with C. sublineolum. We have taken a genetic approach to investigate the possible overlap between the two sub-branches of flavonoid biosynthesis in sorghum that lead to Phlobaphenes and 3-deoxyanthocyanidin phytoalexins. A sorghum line with a functional y1 gene synthesizes 3-deoxyanthocyanidins as well as Phlobaphenes. However, a progenitor line with the mutable Y1-candystripe (Y1-cs) allele shows variable levels of biosynthesis of these compounds. The Y1-cs allele carries a copy of the Candystripe1 (Cs1) transposable element in the y1 gene. We demonstrate here that the variability in the expression of 3-deoxyanthocyanidins produced in individual mesocotyls of hyper-mutable Y1-cs plants is a function of the activity of the y1 gene. TheCs1 insertion in the Y1-cs allele blocks y1 function, while excision of Cs1 out of they1 locus restores the gene to a functional state. The combined molecular and biochemical characterization of sibling plants confirms that the allelic state of the y1 gene is completely correlated with the production of phytoalexins in response to fungal infection. These results provide support for the idea that the y1 gene regulates the biosynthesis of both 3-deoxyanthocyanidin phytoalexins and Phlobaphene pigments in sorghum.
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Molecular characterization of a mutable pigmentation phenotype and isolation of the first active transposable element from Sorghum bicolor.
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Surinder Chopra, Volker Brendel, Jianbo Zhang, John D. Axtell, Thomas PetersonAbstract:Accumulation of red Phlobaphene pigments in sorghum grain pericarp is under the control of the Y gene. A mutable allele of Y, designated as y-cs (y-candystripe), produces a variegated pericarp phenotype. Using probes from the maize p1 gene that cross-hybridize with the sorghum Y gene, we isolated the y-cs allele containing a large insertion element. Our results show that the Y gene is a member of the MYB-transcription factor family. The insertion element, named Candystripe1 (Cs1), is present in the second intron of the Y gene and shares features of the CACTA superfamily of transposons. Cs1 is 23,018 bp in size and is bordered by 20-bp terminal inverted repeat sequences. It generated a 3-bp target site duplication upon insertion within the Y gene and excised from y-cs, leaving a 2-bp footprint in two cases analyzed. Reinsertion of the excised copy of Cs1 was identified by Southern hybridization in the genome of each of seven red pericarp revertant lines tested. Cs1 is the first active transposable element isolated from sorghum. Our analysis suggests that Cs1-homologous sequences are present in low copy number in sorghum and other grasses, including sudangrass, maize, rice, teosinte, and sugarcane. The low copy number and high transposition frequency of Cs1 imply that this transposon could prove to be an efficient gene isolation tool in sorghum.
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Specificities Encode Myb-Homologous Proteins with C-Terminal Replacements
1996Co-Authors: Surinder Chopra, Prasanna Athma, Thomas PetersonAbstract:The maize P gene is a transcriptional regulator of genes encoding enzymes for flavonoid biosynthesis in the pathway leading to the production of a red Phlobaphene pigment. Multiple alleles of the P gene confer distinct patterns of pigmen? tation to specific floral organs, such as the kernel pericarp and cob tissues. To determine the basis of allele-specific pigmentation, we have characterized the gene products and transcript accumulation patterns of the P-wr allele, which specifies colorless pericarps and red cob tissues. RNA transcripts of P-wr are present in colorless pericarps as well as in the colored cob tissues; however, the expression of P-wr in pericarp does not induce the accumulation of transcripts from the C2 and A1 genes, which encode enzymes for flavonoid pigment biosynthesis. The coding sequences of P-wr were compared with the P-rr allele, which specifies red pericarp and red cob. The P-wr and P-rr cDNA sequences are very similar in their 5' regions. There are only two nucleotide changes that result in amino acid differences; both are outside of the Myb-homologous DNA binding domain. In contrast, the 3' coding region of P-rr is replaced by a unique 210-bp sequence in P-wr. The predicted P-wr protein has a C-terminal sequence resembling a cysteine-containing metal binding domain that is not present in the P-rr protein. These results indicate that the differential pericarp pigmentation specified by the P-rr and P-wr alleles does not result from an absence of P-wr transcripts in pericarps. Rather, the allelespecific patterns of P-rr and P-wr pigmentation may be associated with structural differences in the proteins encoded by each allele.
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Alleles of the maize P gene with distinct tissue specificities encode Myb-homologous proteins with C-terminal replacements.
The Plant Cell, 1996Co-Authors: Surinder Chopra, Prasanna Athma, Thomas PetersonAbstract:The maize P gene is a transcriptional regulator of genes encoding enzymes for flavonoid biosynthesis in the pathway leading to the production of a red Phlobaphene pigment. Multiple alleles of the P gene confer distinct patterns of pigmentation to specific floral organs, such as the kernel pericarp and cob tissues. To determine the basis of allele-specific pigmentation, we have characterized the gene products and transcript accumulation patterns of the P-wr allele, which specifies colorless pericarps and red cob tissues. RNA transcripts of P-wr are present in colorless pericarps as well as in the colored cob tissues; however, the expression of P-wr in pericarp does not induce the accumulation of transcripts from the C2 and A1 genes, which encode enzymes for flavonoid pigment biosynthesis. The coding sequences of P-wr were compared with the P-rr allele, which specifies red pericarp and red cob. The P-wr and P-rr cDNA sequences are very similar in their 59 regions. There are only two nucleotide changes that result in amino acid differences; both are outside of the Myb-homologous DNA binding domain. In contrast, the 39 coding region of P-rr is replaced by a unique 210-bp sequence in P-wr. The predicted P-wr protein has a C-terminal sequence resembling a cysteine-containing metal binding domain that is not present in the P-rr protein. These results indicate that the differential pericarp pigmentation specified by the P-rr and P-wr alleles does not result from an absence of P-wr transcripts in pericarps. Rather, the allele-specific patterns of P-rr and P-wr pigmentation may be associated with structural differences in the proteins encoded by each allele.
W. Lange - One of the best experts on this subject based on the ideXlab platform.
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Über die Extraktstoffe des Stammaterials der Kletterpalme Korthalsia rigida Blume
European Journal of Wood and Wood Products, 1992Co-Authors: W. LangeAbstract:Die Extraktstoffe des Stammaterials vonKorthalsia rigida Blume wurden durch sukzessive Extraktion mit Losungsmitteln steigender Polaritat isoliert. Die lipophilen Extrakte bestehen hauptsachlich aus freien Sauren, Glyceriden und Sterinestern neben freien Sterinen. Hauptbestandteile der Sauren (frei und verestert) sind Palmitin-, Linolen- und Linolsauren. Daneben konnten in sehr geringen Mengen als freie Sauren Dehydroabietinsaure sowie drei weitere Diterpensauren identifiziert werden. Im Gemisch der freien Sauren des Etherextraktes liegt p-Hydroxybenzosaure in groseren Mengen vor. Die Hauptmenge der Extraktbestandteile findet sich in den polaren Extraktfraktionen, die neben niedermolekularen Zuckern hauptsachlich kondensierte Gerbstoffe und verwandte naturliche Phlobaphene enthalten.
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Über die Extraktstoffe des Stammaterials der Kletterpalme Korthalsia rigida Blume
Holz als Roh- und Werkstoff, 1992Co-Authors: W. LangeAbstract:Die Extraktstoffe des Stammaterials von Korthalsia rigida Blume wurden durch sukzessive Extraktion mit Lösungsmitteln steigender Polarität isoliert. Die lipophilen Extrakte bestehen hauptsächlich aus freien Säuren, Glyceriden und Sterinestern neben freien Sterinen. Hauptbestandteile der Säuren (frei und verestert) sind Palmitin-, Linolen- und Linolsäuren. Daneben konnten in sehr geringen Mengen als freie Säuren Dehydroabietinsäure sowie drei weitere Diterpensäuren identifiziert werden. Im Gemisch der freien Säuren des Etherextraktes liegt p-Hydroxybenzosäure in größeren Mengen vor. Die Hauptmenge der Extraktbestandteile findet sich in den polaren Extraktfraktionen, die neben niedermolekularen Zuckern hauptsächlich kondensierte Gerbstoffe und verwandte natürliche Phlobaphene enthalten. The extractives from the stems of Korthalsia rigida Blume were isolated by successive extractions with solvents of increasing polarity. The lipophilic extractives mainly consist of free fatty acids, glycerides and sterol esters besides of free sterols. Principal components of the acids (free and esterified) are palmitic, linolenic, and linolic acid. Furthermore, very small amounts of dehydroabietic acid and three other diterpene acids have been identified as free acids. In the mixture of the free acids from the ether extract a fairly high amount of p-hydroxy benzoic acid is present. The bulk of the extraneous components is present in the polar extract fractions which contain besides of simple sugars mainly condensed tannins and related natural pholobaphenes.
Iffa Gaffoor - One of the best experts on this subject based on the ideXlab platform.
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Plant Pathology Seminar Series - Fall Semester 2011
2020Co-Authors: Iffa GaffoorAbstract:In sorghum (Sorghum bicolor), a set of phytoalexins belonging to the 3-deoxyanthocyanidin class that include luteolinidin, apigeninidin and their derivatives are induced at the site of infection in response to pathogenic and non-pathogenic fungi. These compounds have structural similarities to flavonoids which are precursors of brick red Phlobaphene pigments that accumulate during plant development in sorghum seed pericarp, glumes and other tissues. Sorghum yellow seed1 (y1) encodes a MYB transcription factor that regulates Phlobaphene biosynthesis. We have isolated sorghum mutants carrying y1 loss of function alleles that do not accumulate red Phlobaphene pigments. Molecular characterization of the loss of function y1 alleles shows a partial deletion in y1 sequence. These null alleles designated as y1-ww (white pericarp, white glumes) do not accumulate 3-deoxyanthocyanidin phytoalexins when challenged with Cochliobolus heterostrophus. Absence of phytoalexin synthesis in the y1-ww background further enhances its susceptibility to Colletotrichum sublineolum, a fungus that causes anthracnose disease in sorghum. In fungal inoculated y1-ww seedlings, we did not detect steady state transcripts of y1 or its target genes in the flavonoid pathway. Overall results indicate that the sorghum 3-deoxyanthocyanidin phytoalexins and resistance to Colletotrichum sublineolum in sorghum requires a functional y1 gene. We are now working towards transferring this trait to maize and those results will be presented.
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The Dominant and Poorly Penetrant Phenotypes of Maize Unstable factor for orange1 Are Caused by DNA Methylation Changes at a Linked Transposon
The Plant Cell, 2018Co-Authors: Kameron T. Wittmeyer, Iffa Gaffoor, Debamalya Chatterjee, Yinping Jiao, Po-hao Wang, Doreen WareAbstract:The maize mutant Unstable factor for orange1 (Ufo1) has been implicated in the epigenetic modifications of pericarp color1 (p1), which regulates the production of flavonoid pigments Phlobaphenes. Here we show that the ufo1 gene maps to a genetically recalcitrant region near the centromere on chromosome 10. Transcriptome analysis of the Ufo1-1 mutant allele and wild type plants identified a candidate gene in the mapping region using a comparative sequence-based approach. The candidate gene, GRMZM2G053177 is overexpressed by g 45-fold in multiple tissues of Ufo1-1. Ectopic overexpression of this gene explains the dominance of Ufo1-1 and its phenotypes. In the mutant stock, GRMZM2G053177 has a unique transcript which originates within a CACTA transposon inserted in the first intron of the gene, and it is missing the first four codons of the wild type transcript. Expression of GRMZM2G053177 is regulated by the DNA methylation status of the CACTA transposon, explaining the incomplete penetrance and poor expressivity of Ufo1-1. Transgenic overexpression lines of GRMZM2G053177¬ [Ufo1-1] phenocopy the p1 induced pigmentation in coleoptile, tassel, leaf sheath, husk, pericarp, and cob glumes. Transcriptome analysis from Ufo1 vs. wild type tissues show several stress induced pathways related to abiotic and biotic stress. Thus, this study addresses the enigma of Ufo1 in maize, unsolved g50 years.
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Comparative proteomics analysis by DIGE and iTRAQ provides insight into the regulation of phenylpropanoids in maize.
Journal of Proteomics, 2013Co-Authors: Michael L. Robbins, Iffa Gaffoor, Rajandeep S. Sekhon, Po-hao Wang, Marcia M. De O. Buanafina, Jai S. Rohila, Surinder ChopraAbstract:Abstract The maize pericarp color1 ( p1 ) gene encodes a Myb transcription factor that regulates the accumulation of 3-deoxyflavonoid pigments called Phlobaphenes. The Unstable factor for orange1 ( Ufo1 ) is a dominant epigenetic modifier of the p1 that results in ectopic pigmentation in pericarp. Presence of Ufo1-1 correlates with pleiotropic growth and developmental defects. To investigate the Ufo1-1 -induced changes in the proteome, we conducted comparative proteomics analysis of P1-wr; Ufo1-1 pericarps using the 2-D DIGE and iTRAQ techniques. Most of the identified proteins were found to be involved in glycolysis, protein synthesis and modification, flavonoid and lignin biosynthesis and defense responses. Further, immunoblot analysis of internode protein extracts demonstrated that caffeoyl CoA O-methyltransferase (COMT) is post-transcriptionally down regulated in P1-wr; Ufo1-1 plants. Consistent with the down regulation of COMT, the concentrations of p -coumaric acid, syringaldehydes, and lignin are reduced in P1-wr ; Ufo1-1 internodes. The reductions in these phenylpropanoids correlate with the bent stalk and stunted growth of P1-wr ; Ufo1-1 plants. Finally, over-expression of the p1 in transgenic plants is also correlated with a lodging phenotype and reduced COMT expression. We conclude that ectopic expression of p1 can result in developmental defects that are correlated with altered regulation and synthesis of phenylpropanoid compounds including lignin. Biological significance Transcription factors have specific expression patterns that ensure that the biochemical pathways under their control are active in relevant tissues. Plant breeders can select for alleles of transcription factors that produce desirable expression patterns to improve a plant's growth, development, and defense against insects and pathogens. The resulting de novo accumulation of metabolites in plant tissues in significant quantities could have beneficial and/or detrimental consequences. To understand this problem we investigated how the aberrant expression of a classically-studied transcription factor pericarp color1 ( p1 ) which regulates phenylpropanoid metabolism, affects the maize proteome in pericarp tissue. We utilized a dominant mutant Unstable factor for orange 1-1 ( Ufo1-1 ) which reduces the epigenetic suppression of p1 in various tissues throughout the maize plant. Our proteomic analysis shows how, in the presence of Ufo1-1 , key enzymes of the glycolytic and shikimic acid pathways were modulated to produce substrates required for flavonoid synthesis. The finding that the presence of Ufo1-1 affected the expression levels of various enzymes in the lignin pathway was of particular interest. We show that lignin was reduced in Ufo1-1 plants expressing p1 and was associated with the post-transcriptional down regulation of CoA O-methyltransferase (COMT) enzyme. We further correlated the down-regulation of COMT with plant bending phenotype in Ufo1-1 plants expressing p1 and to a stalk lodging phenotype of transgenic p1 plants. This study demonstrates that although there can be adverse consequences to aberrantly overexpressing transcription factors, there might also be benefits such as being able to reduce lignin content for biofuel crops. However, more research will be required to understand the genetic and epigenetic regulation of transcription factors and how their expression can be optimized to obtain desired traits in preferred tissue types. This article is part of a Special Issue entitled: Translational Plant Proteomics.
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Flavonoid Phytoalexin Dependent Resistance to Anthracnose Leaf Blight Requires a Functional yellow seed1 in Sorghum bicolor
Genetics, 2010Co-Authors: Farag Ibraheem, Iffa Gaffoor, Surinder ChopraAbstract:In Sorghum bicolor, a group of phytoalexins are induced at the site of infection by Colletotrichum sublineolum, the anthracnose fungus. These compounds, classified as 3-deoxyanthocyanidins, have structural similarities to the precursors of Phlobaphenes. Sorghum yellow seed1 (y1) encodes a MYB transcription factor that regulates Phlobaphene biosynthesis. Using the candystripe1 transposon mutagenesis system in sorghum, we have isolated functional revertants as well as loss-of-function alleles of y1. These near-isogenic lines of sorghum show that, compared to functionally revertant alleles, loss of y1 lines do not accumulate Phlobaphenes. Molecular characterization of two null y1 alleles shows a partial internal deletion in the y1 sequence. These null alleles, designated as y1-ww1 and y1-ww4, do not accumulate 3-deoxyanthocyanidins when challenged with the nonpathogenic fungus Cochliobolus heterostrophus. Further, as compared to the wild-type allele, both y1-ww1 and y1-ww4 show greater susceptibility to the pathogenic fungus C. sublineolum. In fungal-inoculated wild-type seedlings, y1 and its target flavonoid structural genes are coordinately expressed. However, in y1-ww1 and y1-ww4 seedlings where y1 is not expressed, steady-state transcripts of its target genes could not be detected. Cosegregation analysis showed that the functional y1 gene is genetically linked with resistance to C. sublineolum. Overall results demonstrate that the accumulation of sorghum 3-deoxyanthocyanidin phytoalexins and resistance to C. sublineolum in sorghum require a functional y1 gene.
Michael Fromm - One of the best experts on this subject based on the ideXlab platform.
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elements of the maize a1 promoter required for transactivation by the anthocyanin b c1 or Phlobaphene p regulatory genes
The Plant Cell, 1994Co-Authors: Jutta A Tuerck, Michael FrommAbstract:The extensive genetic and molecular characterization of the flavonoid pathway9s structural and regulatory genes has provided some of the most detailed knowledge of gene interactions in plants. In maize flavonoid biosynthesis, the A1 gene is independently regulated in the anthocyanin and Phlobaphene pathways. Anthocyanin production requires the expression of the C1 or PI and R or B regulatory genes, whereas Phlobaphene production requires only the P regulatory gene. By deletion analysis of the A1 promoter, we show that the sequences between -123 and -88 are critical for activation by anthocyanin and Phlobaphene regulatory genes. Linker-scanner mutations indicated that the -123 to -100 region is more important for transactivation by the P protein. The -98 to -88 region is more important for B/C1 transactivation and shows a strong homology with the region of the Bz1 anthocyanin structural gene promoter shown to be activated by B/C1 and not by P. We identified a 14-bp consensus sequence that is also present in the promoters of three other genes in the anthocyanin pathway, and we propose a model for how the flavonoid regulatory proteins interact with the promoters of the structural genes.