New Insights on Structures Forming the Lignin-Like Fractions of Ancestral Plants

Autor: Gisela Marques, Ángel T. Martínez, Ana Gutiérrez, José C. del Río, Jorge Rencoret, Marta Pérez-Boada, Pui Ying Lam, Yuki Tobimatsu, Francisco J. Ruiz-Dueñas, José María Barrasa
Přispěvatelé: Ministerio de Economía, Industria y Competitividad (España), European Commission, Rencoret, Jorge, Gutiérrez Suárez, Ana, Marques, Gisela, Río Andrade, José Carlos del, Tobimatsu, Yuki, Lam, Pui Ying, Pérez-Boada, Marta, Ruiz-Dueñas, F. J., Barrasa González, José María, Martínez, Ángel T., Rencoret, Jorge [0000-0003-2728-7331], Gutiérrez Suárez, Ana [0000-0002-8823-9029], Marques, Gisela [0000-0002-6431-8267], Río Andrade, José Carlos del [0000-0002-3040-6787], Tobimatsu, Yuki [0000-0002-7578-7392, Lam, Pui Ying [0000-0001-5025-1308], Pérez-Boada, Marta [0000-0002-3288-0853], Ruiz-Dueñas, F. J. [0000-0002-9837-5665], Barrasa González, José María [0000-0002-3904-5375], Martínez, Ángel T. [0000-0002-1584-2863]
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Frontiers in Plant Science, Vol 12 (2021)
Frontiers in Plant Science
Digital.CSIC. Repositorio Institucional del CSIC
instname
ISSN: 1664-462X
Popis: 14 páginas.- 6 figuras.- 3 tablas.- referencias.- The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpls.2021.740923/full#supplementary-material
In the present work, lignin-like fractions were isolated from several ancestral plants –including moss (Hypnum cupressiforme and Polytrichum commune), lycophyte (Selaginella kraussiana), horsetail (Equisetum palustre), fern (Nephrolepis cordifolia and Pteridium aquilinum), cycad (Cycas revoluta), and gnetophyte (Ephedra fragilis) species– and structurally characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Py-GC/MS yielded marker compounds characteristic of lignin units, except in the H. cupressiforme, P. commune and E. palustre “lignins,” where they were practically absent. Additional structural information on the other five samples was obtained from 2D-NMR experiments displaying intense correlations signals of guaiacyl (G) units in the fern and cycad lignins, along with smaller amounts of p-hydroxyphenyl (H) units. Interestingly, the lignins from the lycophyte S. kraussiana and the gnetophyte E. fragilis were not only composed of G- and H-lignin units but they also incorporated significant amounts of the syringyl (S) units characteristic of angiosperms, which appeared much later in plant evolution, most probably due to convergent evolution. The latter finding is also supported by the abundance of syringol derivatives after the Py-GC/MS analyses of these two samples. Regarding lignin structure, β−O−4′ alkyl-aryl ethers were the most abundant substructures, followed by condensed β−5′ phenylcoumarans and β−β′ resinols (and dibenzodioxocins in the fern and cycad lignins). The highest percentages of alkyl-aryl ether structures correlated with the higher S/G ratio in the S. Kraussiana and E. fragilis lignin-like fractions. More interestingly, apart from the typical monolignol-derived lignin units (H, G and S), other structures, assigned to flavonoid compounds never reported before in natural lignins (such as amentoflavone, apigenin, hypnogenol B, kaempferol, and naringenin), could also be identified in the HSQC spectra of all the lignin-like fractions analyzed. With this purpose, in vitro synthesized coniferyl-naringenin and coniferyl-apigenin dehydrogenation polymers were used as standards. These flavonoids were abundant in H. cupressiforme appearing as the only constituents of the moss lignin-like fraction (including 84% of dimeric hypnogenol B) and their abundance decreased in those of S. Kraussiana (with amentoflavone and naringenin representing 14% of the total aromatic units), and the two ancient gymnosperms (0.4–1.2%) and ferns (0–0.7%).
This work was funded by the Spanish Ministry of Industry, Economy and Competitiveness projects BIO2017-86559-R, AGL2017-83036-R, and PID2020-118968RB-I00, cofinanced by FEDER funds, by the Junta de Andalucía project P20-00017, and by the CSIC projects PIE-202120E019 and PIE-202040E185. We would like to acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).
Databáze: OpenAIRE
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