Effects ofPHENYLALANINE AMMONIA LYASE(PAL) knockdown on cell wall composition, biomass digestibility, and biotic and abiotic stress responses inBrachypodium

Cass, Cynthia L.; Peraldi, Antoine; Dowd, Patrick F.; Mottiar, Yaseen; Santoro, Nicholas; Karlen, Steven D.; Bukhman, Yury V.; Foster, Cliff E.; Thrower, Nicholas; Bruno, Laura C.; Moskvin, Oleg V.; Johnson, Eric T.; Willhoit, Megan E.; Phutane, Megha; Ralph, John; Mansfield, Shawn D.; Nicholson, P.

doi:10.1093/jxb/erv269

Cited by 172 publications

(113 citation statements)

References 88 publications

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“…CAD, Cinnamyl alcohol dehydrogenase; CCoAOMT, caffeoyl-CoA O-methyltransferase; CCR, cinnamoyl-CoA reductase; CGT, Cglycosyltransferase; C3H, p-coumarate 3-hydroxylase; C4H, cinnamate-4-hydroxylase; CHI, chalcone isomerase; 4CL, 4-coumarate:CoA ligase; COMT, caffeic acid O-methyltransferase; CSE, caffeoyl shikimate esterase; F2H, flavanone 2-hydroxylase; F3H, naringenin 3-dioxygenase; F39H, flavonoid 39-hydroxylase; F5H, ferulate 5-hydroxylase; F59H, flavonoid 59-hydroxylase; FLS, flavonol synthase; FNS, flavone synthase; FOMT, flavonoid O-methyltransferase; HCALDH, hydroxycinnamaldehyde dehydrogenase; HCT, p-hydroxycinnamoyl-CoA:quinate/shikimate p-hydroxycinnamoyltransferase; HQT, hydroxycinnamoyl-CoA:quinate hydroxycinnamoyltransferase; PAL, Phe ammonia lyase; PMT, p-coumaroyl-CoA:monolignol transferase; TAL, Tyr ammonia lyase; UGT, UDP-glucosyltransferase. The relation between TAL and PAL activity has been reported by Rö sler et al (1997) for maize and by Cass et al (2015) for brachypodium. Enzymes involved in the general phenylpropanoid (PAL, TAL, C4H, 4CL, HCT, C3H, and CCoAOMT) and monolignol-specific (CCR, F5H, COMT, and CAD) pathways are described by Guillaumie et al (2007).…”

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confidence: 58%

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

et al. 2016

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Lignin is a phenolic heteropolymer that is deposited in secondary-thickened cell walls, where it provides mechanical strength. A recent structural characterization of cell walls from monocot species showed that the flavone tricin is part of the native lignin polymer, where it is hypothesized to initiate lignin chains. In this study, we investigated the consequences of altered tricin levels on lignin structure and cell wall recalcitrance by phenolic profiling, nuclear magnetic resonance, and saccharification assays of the naturally silenced maize (Zea mays) C2-Idf (inhibitor diffuse) mutant, defective in the CHALCONE SYNTHASE Colorless2 (C2) gene. We show that the C2-Idf mutant produces highly reduced levels of apigenin-and tricin-related flavonoids, resulting in a strongly reduced incorporation of tricin into the lignin polymer. Moreover, the lignin was enriched in b-b and b-5 units, lending support to the contention that tricin acts to initiate lignin chains and that, in the absence of tricin, more monolignol dimerization reactions occur. In addition, the C2-Idf mutation resulted in strikingly higher Klason lignin levels in the leaves. As a consequence, the leaves of C2-Idf mutants had significantly reduced saccharification efficiencies compared with those of control plants. These findings are instructive for lignin engineering strategies to improve biomass processing and biochemical production.

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confidence: 58%

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

et al. 2016

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“…As with other putative/known tricin biosynthetic genes, such as OsCHS1 (Shih et al, 2008;Hong et al, 2012), OsCHI (Shih et al, 2008), and OsC59H (CYP75B4; Lam et al, 2015), OsFNSII (CYP93G1; Lam et al, 2014) was expressed most prominently in culm at reproductive and ripening stages, where cell wall lignification typically occurs. We confirmed the concurrent expression of putative/known monolignol biosynthetic genes, including OsCAD2 (Zhang et al, 2006;Koshiba et al, 2013b), OsCAldOMT1 (Koshiba et al, 2013a), and OsPMT (Petrik et al, 2014), as well as the common phenylpropanoid genes OsPAL1/2 (Cass et al, 2015) and Os4CL3 (Gui et al, 2011;Supplemental Fig. S1).…”

Section: Expression Of Flavonoid and Monolignol Biosynthetic Genes Insupporting

confidence: 69%

Disrupting Flavone Synthase II Alters Lignin and Improves Biomass Digestibility

et al. 2017

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Lignin, a ubiquitous phenylpropanoid polymer in vascular plant cell walls, is derived primarily from oxidative couplings of monolignols (p-hydroxycinnamyl alcohols). It was discovered recently that a wide range of grasses, including cereals, utilize a member of the flavonoids, tricin (39,59-dimethoxyflavone), as a natural comonomer with monolignols for cell wall lignification. Previously, we established that cytochrome P450 93G1 is a flavone synthase II (OsFNSII) indispensable for the biosynthesis of soluble tricin-derived metabolites in rice (Oryza sativa). Here, our tricin-deficient fnsII mutant was analyzed further with an emphasis on its cell wall structure and properties. The mutant is similar in growth to wild-type control plants with normal vascular morphology. Chemical and nuclear magnetic resonance structural analyses demonstrated that the mutant lignin is completely devoid of tricin, indicating that FNSII activity is essential for the deposition of tricin-bound lignin in rice cell walls. The mutant also showed substantially reduced lignin content with decreased syringyl/guaiacyl lignin unit composition. Interestingly, the loss of tricin in the mutant lignin appears to be partially compensated by incorporating naringenin, which is a preferred substrate of OsFNSII. The fnsII mutant was further revealed to have enhanced enzymatic saccharification efficiency, suggesting that the cell wall recalcitrance of grass biomass may be reduced through the manipulation of the flavonoid monomer supply for lignification.

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“…Phenylpropanoids function as inducible antimicrobial compounds and as signaling molecules in plant-pathogen responses (Dixon et al, 2002;Naoumkina et al, 2010). Moreover, phenylpropanoid metabolism is the most important plant metabolic pathway during plant defense against biotic stress (La Camera et al, 2004;Cass et al, 2015). Lignin biosynthesis is a downstream branch of the phenylpropanoid pathway.…”

Section: Introductionmentioning

confidence: 99%

Melatonin enhances cotton immunity to Verticillium wilt via manipulating lignin and gossypol biosynthesis

Zhang

et al. 2019

The Plant Journal

156

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SummaryPlants endure challenging environments in which they are constantly threatened by diverse pathogens. The soil‐borne fungus Verticillium dahliae is a devastating pathogen affecting many plant species including cotton, in which it significantly reduces crop yield and fiber quality. Melatonin involvement in plant immunity to pathogens has been reported, but the mechanisms of melatonin‐induced plant resistance are unclear. In this study, the role of melatonin in enhancing cotton resistance to V. dahliae was investigated. At the transcriptome level, exogenous melatonin increased the expression of genes in phenylpropanoid, mevalonate (MVA), and gossypol pathways after V. dahliae inoculation. As a result, lignin and gossypol, the products of these metabolic pathways, significantly increased. Silencing the serotonin N‐acetyltransferase 1 (GhSNAT1) and caffeic acid O‐methyltransferase (GhCOMT) melatonin biosynthesis genes compromised cotton resistance, with reduced lignin and gossypol levels after V. dahliae inoculation. Exogenous melatonin pre‐treatment prior to V. dahliae inoculation restored the level of cotton resistance reduced by the above gene silencing effects. Melatonin levels were higher in resistant cotton cultivars than in susceptible cultivars after V. dahliae inoculation. The findings indicate that melatonin affects lignin and gossypol synthesis genes in phenylpropanoid, MVA, and gossypol pathways, thereby enhancing cotton resistance to V. dahliae.

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Effects ofPHENYLALANINE AMMONIA LYASE(PAL) knockdown on cell wall composition, biomass digestibility, and biotic and abiotic stress responses inBrachypodium

Abstract: HighlightReducing the function of PAL, the first enzyme in the phenylpropanoid pathway, in Brachypodium distachyon alters cell wall composition, increases fungal susceptibility, but minimally affects caterpillar herbivory and abiotic stress tolerance.

Cited by 172 publications

References 88 publications

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

Disrupting Flavone Synthase II Alters Lignin and Improves Biomass Digestibility

Melatonin enhances cotton immunity to Verticillium wilt via manipulating lignin and gossypol biosynthesis

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