Environmental Stresses of Field Growth Allow Cinnamyl Alcohol Dehydrogenase-Deficient <i>Nicotiana attenuata</i> Plants to Compensate for their Structural Deficiencies

Kaur, Harleen; Shaker, Kamel H.; Heinzel, Nicolas; Ralph, John; Gàlis, Ivan; Baldwin, Ian Thomas

doi:10.1104/pp.112.196717

Cited by 55 publications

(53 citation statements)

References 120 publications

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“…However, it was reported recently that Nicotiana attenuata plants with silenced CAD gene, had robust phenotype when grown in a greenhouse, but showed normal phenotype when planted in a field [19]. It was found that down-regulation had not regressed, only various compounds where inbuilt in lignin structure to ensure up-right orientation of the stalk.…”

Section: Discussionmentioning

confidence: 99%

Manipulating cinnamyl alcohol dehydrogenase (CAD) expression in flax affects fibre composition and properties

et al. 2014

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BackgroundIn recent decades cultivation of flax and its application have dramatically decreased. One of the reasons for this is unpredictable quality and properties of flax fibre, because they depend on environmental factors, retting duration and growing conditions. These factors have contribution to the fibre composition, which consists of cellulose, hemicelluloses, lignin and pectin. By far, it is largely established that in flax, lignin reduces an accessibility of enzymes either to pectin, hemicelluloses or cellulose (during retting or in biofuel synthesis and paper production).Therefore, in this study we evaluated composition and properties of flax fibre from plants with silenced CAD (cinnamyl alcohol dehydrogenase) gene, which is key in the lignin biosynthesis. There is evidence that CAD is a useful tool to improve lignin digestibility and/or to lower the lignin levels in plants.ResultsTwo studied lines responded differentially to the introduced modification due to the efficiency of the CAD silencing. Phylogenetic analysis revealed that flax CAD belongs to the “bona-fide” CAD family. CAD down-regulation had an effect in the reduced lignin amount in the flax fibre cell wall and as FT-IR results suggests, disturbed lignin composition and structure. Moreover introduced modification activated a compensatory mechanism which was manifested in the accumulation of cellulose and/or pectin. These changes had putative correlation with observed improved fiber’s tensile strength. Moreover, CAD down-regulation did not disturb at all or has only slight effect on flax plants’ development in vivo, however, the resistance against flax major pathogen Fusarium oxysporum decreased slightly. The modification positively affected fibre possessing; it resulted in more uniform retting.ConclusionThe major finding of our paper is that the modification targeted directly to block lignin synthesis caused not only reduced lignin level in fibre, but also affected amount and organization of cellulose and pectin. However, to conclude that all observed changes are trustworthy and correlated exclusively to CAD repression, further analysis of the modified plants genome is necessary. Secondly, this is one of the first studies on the crop from the low-lignin plants from the field trail which demonstrates that such plants could be successfully cultivated in a field.

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Section: Discussionmentioning

confidence: 99%

Manipulating cinnamyl alcohol dehydrogenase (CAD) expression in flax affects fibre composition and properties

et al. 2014

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“…Environmental factors have been shown previously to interact with CAD deficiency in CAD-deficient M. truncatula: the phenotype of these plants was equal to that of the wild type when grown at ambient temperatures, but the plants were dwarfed when grown at elevated temperatures (30°C; Zhao et al, 2013). In contrast, down-regulating CAD in Nicotiana attenuata produced plants with thin and structurally unstable stems when grown in the greenhouse, but the normal phenotype was restored when plants were grown outdoors (Kaur et al, 2012). Hence, it is important to investigate how the hpCAD poplars with this level of lignin alteration will respond when grown in the field, especially regarding biomass and bioethanol yield.…”

Section: Cad1 Down-regulation Does Not Affect Plant Yield Under Greenmentioning

confidence: 93%

Different Routes for Conifer- and Sinapaldehyde and Higher Saccharification upon Deficiency in the Dehydrogenase CAD1

Déjardin²,

et al. 2017

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In the search for renewable energy sources, genetic engineering is a promising strategy to improve plant cell wall composition for biofuel and bioproducts generation. Lignin is a major factor determining saccharification efficiency and, therefore, is a prime target to engineer. Here, lignin content and composition were modified in poplar (Populus tremula 3 Populus alba) by specifically down-regulating CINNAMYL ALCOHOL DEHYDROGENASE1 (CAD1) by a hairpin-RNA-mediated silencing approach, which resulted in only 5% residual CAD1 transcript abundance. These transgenic lines showed no biomass penalty despite a 10% reduction in Klason lignin content and severe shifts in lignin composition. Nuclear magnetic resonance spectroscopy and thioacidolysis revealed a strong increase (up to 20-fold) in sinapaldehyde incorporation into lignin, whereas coniferaldehyde was not increased markedly. Accordingly, ultra-high-performance liquid chromatography-mass spectrometry-based phenolic profiling revealed a more than 24,000-fold accumulation of a newly identified compound made from 8-8 coupling of two sinapaldehyde radicals. However, no additional cinnamaldehyde coupling products could be detected in the CAD1-deficient poplars. Instead, the transgenic lines accumulated a range of hydroxycinnamate-derived metabolites, of which the most prominent accumulation (over 8,500-fold) was observed for a compound that was identified by purification and nuclear magnetic resonance as syringyl lactic acid hexoside. Our data suggest that, upon down-regulation of CAD1, coniferaldehyde is converted into ferulic acid and derivatives, whereas sinapaldehyde is either oxidatively coupled into S9(8-8)S9 and lignin or converted to sinapic acid and derivatives. The most prominent sink of the increased flux to hydroxycinnamates is syringyl lactic acid hexoside. Furthermore, low-extent saccharification assays, under different pretreatment conditions, showed strongly increased glucose (up to +81%) and xylose (up to +153%) release, suggesting that down-regulating CAD1 is a promising strategy for improving lignocellulosic biomass for the sugar platform industry.

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“…Rather than anthocyanins, as in petunia ir-PhCCoAOMT1 plants, changes in coloration in poplar were due to the accumulation of hydroxycinnamic acids. Similarly, silencing of CINNAMYL ALCOHOL DEHYDROGENASE, acting downstream of CCoAOMT1 in the monolignol pathway, resulted in a reddish xylem in Nicotiana attenuata plants due to the accumulation of hydroxycinnamaldehydes (Kaur et al, 2012). Interestingly, more benzoic acid (C 6 -C 1 )-related compounds accumulated in poplar (p-hydroxybenzoate attached to lignin) and Arabidopsis (four benzenoic hexose esters) when CCoAOMT expression was reduced.…”

Section: Discussionmentioning

confidence: 99%

CCoAOMT Down-Regulation Activates Anthocyanin Biosynthesis in Petunia

et al. 2015

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Anthocyanins and volatile phenylpropenes (isoeugenol and eugenol) in petunia (Petunia hybrida) flowers have the precursor 4-coumaryl coenzyme A (CoA) in common. These phenolics are produced at different stages during flower development. Anthocyanins are synthesized during early stages of flower development and sequestered in vacuoles during the lifespan of the flowers. The production of isoeugenol and eugenol starts when flowers open and peaks after anthesis. To elucidate additional biochemical steps toward (iso)eugenol production, we cloned and characterized a caffeoyl-coenzyme A O-methyltransferase (PhCCoAOMT1) from the petals of the fragrant petunia 'Mitchell'. Recombinant PhCCoAOMT1 indeed catalyzed the methylation of caffeoyl-CoA to produce feruloyl CoA. Silencing of PhCCoAOMT1 resulted in a reduction of eugenol production but not of isoeugenol. Unexpectedly, the transgenic plants had purple-colored leaves and pink flowers, despite the fact that cv Mitchell lacks the functional R2R3-MYB master regulator ANTHOCYANIN2 and has normally white flowers. Our results indicate that down-regulation of PhCCoAOMT1 activated the anthocyanin pathway through the R2R3-MYBs PURPLE HAZE (PHZ) and DEEP PURPLE, with predominantly petunidin accumulating. Feeding cv Mitchell flowers with caffeic acid induced PHZ expression, suggesting that the metabolic perturbation of the phenylpropanoid pathway underlies the activation of the anthocyanin pathway. Our results demonstrate a role for PhCCoAOMT1 in phenylpropene production and reveal a link between PhCCoAOMT1 and anthocyanin production.

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Environmental Stresses of Field Growth Allow Cinnamyl Alcohol Dehydrogenase-Deficient Nicotiana attenuata Plants to Compensate for their Structural Deficiencies

Cited by 55 publications

References 120 publications

Manipulating cinnamyl alcohol dehydrogenase (CAD) expression in flax affects fibre composition and properties

Manipulating cinnamyl alcohol dehydrogenase (CAD) expression in flax affects fibre composition and properties

Different Routes for Conifer- and Sinapaldehyde and Higher Saccharification upon Deficiency in the Dehydrogenase CAD1

CCoAOMT Down-Regulation Activates Anthocyanin Biosynthesis in Petunia

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