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  1. Article ; Online: Modulating auxin response stabilizes tomato fruit set.

    Israeli, Alon / Schubert, Ramona / Man, Nave / Teboul, Naama / Serrani Yarce, Juan Carlos / Rosowski, Emily E / Wu, Miin-Feng / Levy, Matan / Efroni, Idan / Ljung, Karin / Hause, Bettina / Reed, Jason W / Ori, Naomi

    Plant physiology

    2023  Volume 192, Issue 3, Page(s) 2336–2355

    Abstract: Fruit formation depends on successful fertilization and is highly sensitive to weather fluctuations that affect pollination. Auxin promotes fruit initiation and growth following fertilization. Class A auxin response factors (Class A ARFs) repress ... ...

    Abstract Fruit formation depends on successful fertilization and is highly sensitive to weather fluctuations that affect pollination. Auxin promotes fruit initiation and growth following fertilization. Class A auxin response factors (Class A ARFs) repress transcription in the absence of auxin and activate transcription in its presence. Here, we explore how multiple members of the ARF family regulate fruit set and fruit growth in tomato (Solanum lycopersicum) and Arabidopsis thaliana, and test whether reduction of SlARF activity improves yield stability in fluctuating temperatures. We found that several tomato Slarf mutant combinations produced seedless parthenocarpic fruits, most notably mutants deficient in SlARF8A and SlARF8B genes. Arabidopsis Atarf8 mutants deficient in the orthologous gene had less complete parthenocarpy than did tomato Slarf8a Slarf8b mutants. Conversely, Atarf6 Atarf8 double mutants had reduced fruit growth after fertilization. AtARF6 and AtARF8 likely switch from repression to activation of fruit growth in response to a fertilization-induced auxin increase in gynoecia. Tomato plants with reduced SlARF8A and SlARF8B gene dosage had substantially higher yield than the wild type under controlled or ambient hot and cold growth conditions. In field trials, partial reduction in the SlARF8 dose increased yield under extreme temperature with minimal pleiotropic effects. The stable yield of the mutant plants resulted from a combination of early onset of fruit set, more fruit-bearing branches and more flowers setting fruits. Thus, ARF8 proteins mediate the control of fruit set, and relieving this control with Slarf8 mutations may be utilized in breeding to increase yield stability in tomato and other crops.
    MeSH term(s) Indoleacetic Acids/metabolism ; Fruit/metabolism ; Solanum lycopersicum/genetics ; Plant Breeding ; Arabidopsis/genetics ; Gene Expression Regulation, Plant ; Plant Proteins/genetics ; Plant Proteins/metabolism
    Chemical Substances Indoleacetic Acids ; Plant Proteins
    Language English
    Publishing date 2023-04-10
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 208914-2
    ISSN 1532-2548 ; 0032-0889
    ISSN (online) 1532-2548
    ISSN 0032-0889
    DOI 10.1093/plphys/kiad205
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Targeting hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase for lignin modification in Brachypodium distachyon.

    Serrani-Yarce, Juan Carlos / Escamilla-Trevino, Luis / Barros, Jaime / Gallego-Giraldo, Lina / Pu, Yunqiao / Ragauskas, Art / Dixon, Richard A

    Biotechnology for biofuels

    2021  Volume 14, Issue 1, Page(s) 50

    Abstract: Background: Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) is a central enzyme of the so-called "esters" pathway to monolignols. As originally envisioned, HCT functions twice in this pathway, to form coumaroyl shikimate and then, in ... ...

    Abstract Background: Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) is a central enzyme of the so-called "esters" pathway to monolignols. As originally envisioned, HCT functions twice in this pathway, to form coumaroyl shikimate and then, in the "reverse" direction, to convert caffeoyl shikimate to caffeoyl CoA. The discovery of a caffeoyl shikimate esterase (CSE) that forms caffeic acid directly from caffeoyl shikimate calls into question the need for the reverse HCT reaction in lignin biosynthesis. Loss of function of HCT gives severe growth phenotypes in several dicot plants, but less so in some monocots, questioning whether this enzyme, and therefore the shikimate shunt, plays the same role in both monocots and dicots. The model grass Brachypodium distachyon has two HCT genes, but lacks a classical CSE gene. This study was therefore conducted to evaluate the utility of HCT as a target for lignin modification in a species with an "incomplete" shikimate shunt.
    Results: The kinetic properties of recombinant B. distachyon HCTs were compared with those from Arabidopsis thaliana, Medicago truncatula, and Panicum virgatum (switchgrass) for both the forward and reverse reactions. Along with two M. truncatula HCTs, B. distachyon HCT2 had the least kinetically unfavorable reverse HCT reaction, and this enzyme is induced when HCT1 is down-regulated. Down regulation of B. distachyon HCT1, or co-down-regulation of HCT1 and HCT2, by RNA interference led to reduced lignin levels, with only modest changes in lignin composition and molecular weight.
    Conclusions: Down-regulation of HCT1, or co-down-regulation of both HCT genes, in B. distachyon results in less extensive changes in lignin content/composition and cell wall structure than observed following HCT down-regulation in dicots, with little negative impact on biomass yield. Nevertheless, HCT down-regulation leads to significant improvements in biomass saccharification efficiency, making this gene a preferred target for biotechnological improvement of grasses for bioprocessing.
    Language English
    Publishing date 2021-02-27
    Publishing country England
    Document type Journal Article
    ZDB-ID 2421351-2
    ISSN 1754-6834
    ISSN 1754-6834
    DOI 10.1186/s13068-021-01905-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Targeting hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase for lignin modification in Brachypodium distachyon

    Serrani-Yarce, Juan Carlos / Escamilla-Trevino, Luis / Barros, Jaime / Gallego-Giraldo, Lina / Pu, Yunqiao / Ragauskas, Art / Dixon, Richard A.

    Biotechnology for biofuels. 2021 Dec., v. 14, no. 1

    2021  

    Abstract: BACKGROUND: Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) is a central enzyme of the so-called “esters” pathway to monolignols. As originally envisioned, HCT functions twice in this pathway, to form coumaroyl shikimate and then, in ... ...

    Abstract BACKGROUND: Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) is a central enzyme of the so-called “esters” pathway to monolignols. As originally envisioned, HCT functions twice in this pathway, to form coumaroyl shikimate and then, in the “reverse” direction, to convert caffeoyl shikimate to caffeoyl CoA. The discovery of a caffeoyl shikimate esterase (CSE) that forms caffeic acid directly from caffeoyl shikimate calls into question the need for the reverse HCT reaction in lignin biosynthesis. Loss of function of HCT gives severe growth phenotypes in several dicot plants, but less so in some monocots, questioning whether this enzyme, and therefore the shikimate shunt, plays the same role in both monocots and dicots. The model grass Brachypodium distachyon has two HCT genes, but lacks a classical CSE gene. This study was therefore conducted to evaluate the utility of HCT as a target for lignin modification in a species with an “incomplete” shikimate shunt. RESULTS: The kinetic properties of recombinant B. distachyon HCTs were compared with those from Arabidopsis thaliana, Medicago truncatula, and Panicum virgatum (switchgrass) for both the forward and reverse reactions. Along with two M. truncatula HCTs, B. distachyon HCT2 had the least kinetically unfavorable reverse HCT reaction, and this enzyme is induced when HCT1 is down-regulated. Down regulation of B. distachyon HCT1, or co-down-regulation of HCT1 and HCT2, by RNA interference led to reduced lignin levels, with only modest changes in lignin composition and molecular weight. CONCLUSIONS: Down-regulation of HCT1, or co-down-regulation of both HCT genes, in B. distachyon results in less extensive changes in lignin content/composition and cell wall structure than observed following HCT down-regulation in dicots, with little negative impact on biomass yield. Nevertheless, HCT down-regulation leads to significant improvements in biomass saccharification efficiency, making this gene a preferred target for biotechnological improvement of grasses for bioprocessing.
    Keywords Arabidopsis thaliana ; Brachypodium distachyon ; Medicago truncatula ; Panicum virgatum ; RNA interference ; biofuels ; biomass production ; bioprocessing ; biosynthesis ; biotechnology ; caffeic acid ; cell walls ; esterases ; genes ; grasses ; hydroxycinnamoyltransferase ; lignin ; lignin content ; molecular weight ; saccharification
    Language English
    Dates of publication 2021-12
    Size p. 50.
    Publishing place BioMed Central
    Document type Article
    ZDB-ID 2421351-2
    ISSN 1754-6834
    ISSN 1754-6834
    DOI 10.1186/s13068-021-01905-1
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: 4-Coumarate 3-hydroxylase in the lignin biosynthesis pathway is a cytosolic ascorbate peroxidase.

    Barros, Jaime / Escamilla-Trevino, Luis / Song, Luhua / Rao, Xiaolan / Serrani-Yarce, Juan Carlos / Palacios, Maite Docampo / Engle, Nancy / Choudhury, Feroza K / Tschaplinski, Timothy J / Venables, Barney J / Mittler, Ron / Dixon, Richard A

    Nature communications

    2019  Volume 10, Issue 1, Page(s) 1994

    Abstract: Lignin biosynthesis is evolutionarily conserved among higher plants and features a critical 3-hydroxylation reaction involving phenolic esters. However, increasing evidence questions the involvement of a single pathway to lignin formation in vascular ... ...

    Abstract Lignin biosynthesis is evolutionarily conserved among higher plants and features a critical 3-hydroxylation reaction involving phenolic esters. However, increasing evidence questions the involvement of a single pathway to lignin formation in vascular plants. Here we describe an enzyme catalyzing the direct 3-hydroxylation of 4-coumarate to caffeate in lignin biosynthesis as a bifunctional peroxidase that oxidizes both ascorbate and 4-coumarate at comparable rates. A combination of biochemical and genetic evidence in the model plants Brachypodium distachyon and Arabidopsis thaliana supports a role for this coumarate 3-hydroxylase (C3H) in the early steps of lignin biosynthesis. The subsequent efficient O-methylation of caffeate to ferulate in grasses is substantiated by in vivo biochemical assays. Our results identify C3H as the only non-membrane bound hydroxylase in the lignin pathway and revise the currently accepted models of lignin biosynthesis, suggesting new gene targets to improve forage and bioenergy crops.
    MeSH term(s) Arabidopsis/metabolism ; Ascorbate Peroxidases ; Brachypodium/metabolism ; Caffeic Acids/metabolism ; Coumaric Acids/metabolism ; Cytosol/enzymology ; Lignin/biosynthesis ; Mixed Function Oxygenases/genetics ; Mixed Function Oxygenases/metabolism ; Plant Proteins/genetics ; Plant Proteins/metabolism
    Chemical Substances Caffeic Acids ; Coumaric Acids ; Plant Proteins ; Lignin (9005-53-2) ; Mixed Function Oxygenases (EC 1.-) ; Ascorbate Peroxidases (EC 1.11.1.11) ; caffeic acid (U2S3A33KVM)
    Language English
    Publishing date 2019-04-30
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-019-10082-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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