Retention of lignin in seagrasses:angiosperms that returned to the sea

Abstract

Using Curie-point Pyrolysis Gas Chromatography Mass Spectrometry [Py-GCMS) and Direct Temperature-resolved Mass Spectrometry (DT-bfS), lignin was detected In highly purified preparations (Milled Wood Lignin = hlWL) of various tissues of the seagrasses Zostera rnarina and Posidonia oceanica. The results ind~cate that P. oceanica contains more lign~n than Z. manna and that roots and rhizomes generally contain more Lignin than leaves. It is concluded that the ability to produce lignin is not lost by the angiosperm ancestors of extant seagrasses upon their colonization of the marine environment. Relative lignin abundances in the different tissues appear to be posltlvely correlated with life span. It is suggested that lignification contributes to the longevity of a tissue by protecting lt against microbial attack, but that deposition of lignin in seagrasses is restricted to tissues that show limited growth.

Molecular composition of plant parts and sediment organic matter in a Mediterranean seagrass (Posidonia oceanica) mat

“…The only PY-GC-MS product that could not be identified in any plant material but was present in all samples of the core was ferulic acid ME (0.03 ± 0.01%), which might originate from the rhizome (traces detected in milled-wood-lignin extracts; Klap et al 2000) or, alternatively, from graminoid debris (Schellekens et al 2015), which would imply a minor terrestrial source. In addition, a large discrepancy was found between the relatively high proportions of 4-hydroxy-2-methoxycinnamaldehyde in the mat samples (0.2 ± 0.1%) compared to the traces (0.006%) tentatively identified in the root sample.…”

“…Reported lignin contents of P. oceanica leaves and agaepropili are in the range of 25-30% of their dry weight (Ncibi et al 2009;Khiari et al 2010;Bettaieb et al 2015). However, this is operationally defined Klason lignin (acid-insoluble residues), only a small portion of which corresponds to "true" polyphenolic lignin (Klap et al 2000). Tannins stored in tannin cells 1 It is worth mentioning here that this P. oceanica beach material causes annoying flies, odours and beach size reduction in touristic areas along the Mediterranean coast, and associated expenditure on removal (Khiari et al 2010;Simeone and De Falco 2012;Plis et al 2014).…”

“…Molecular examinations of the composition of the rhizomes and particularly the roots are less frequent. Klap et al (2000) demonstrated that the rhizome and roots have higher lignin contents than the leaves.…”

“…conventional analytical pyrolysis (PY-GC-MS) and Thermally assisted Hydrolysis and Methylation (THM-GC-MS), the latter of which uses a derivatization agent simultaneously to thermal treatment to enhance the structural information obtained for polar aliphatic and phenolic materials (Wampler 1999;Challinor 2001;Shadkami and Helleur 2010). Only Gadel and Bruchet (1987) and Klap et al (2000) studied Posidonia oceanica materials by PY-GC-MS, but they analyzed specific (and unquantified) fractions of humic/fulvic fractions and milled-wood-lignin preparations, respectively. As far as we know, THM-GC-MS has not been applied to P. oceanica materials yet.…”

Isotopic composition of polyhalomethanes from marine macrophytes – systematic effects of the halogen substituents on isotopic composition

“…Seagrasses, however, produce lignins, making phenolic moieties likely PHM precursors in the seagrass incubations. [49] Thus, differences in the PHM precursors may further account for the different isotopic composition of CHBr 3 from seagrass and macroalgae. In contrast to CHBr 3 and CH 2 Br 2 , the d 13 C values of CH 2 I 2 do not show a common trend among all macroalgae experiments but a significant correlation for L. digitata (R 2 ¼ 0.72, n ¼ 16) Here, better fit is obtained using a linear regression (R 2 ¼ 0.83).…”