The role of cell wall phenolics during the early remodelling of cellulose-deficient maize cells

• Published in: Phytochemistry (Oxford) Vol. 170; p. 112219
• Main Authors: Martínez-Rubio, Romina, Centeno, María Luz, García-Angulo, Penélope, Álvarez, Jesús M., Acebes, José Luis, Encina, Antonio
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-02-2020
• Subjects: Cell wall; Cell Wall - chemistry; Cell Wall - metabolism; Cellulose - chemistry; Cellulose - metabolism; Dichlobenil; Ferulic acid; HPLC; Hydroxycinnamates; Maize; p-coumaric acid; Phenols - chemistry; Phenols - metabolism; Phytochemicals - chemistry; Phytochemicals - metabolism; Poaceae; Zea mays - chemistry; Zea mays - cytology; Zea mays - metabolism; Zea mays L; DCB; H; Poaceae; Maize; p-coumaric acid; PDA; Cell wall; Dichlobenil; TFA; Ferulic acid; AX; NH; FA; Zea mays L; HPLC; Hydroxycinnamates; CA; DFA
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2019.112219

The habituation of cultured cells to cellulose biosynthesis inhibitors such as dichlobenil (dichlorobenzonitrile, DCB) has proven a valuable tool to elucidate the mechanisms involved in plant cell wall structural plasticity. Our group has demonstrated that maize cells cope with DCB through a modified cell wall in which cellulose is replaced by a more extensive network of highly cross-linked feruloylated arabinoxylans. In order to gain further insight into the contribution of phenolics to the early remodelling of cellulose-deficient cell walls, a comparative HPLC-PAD analysis was carried out of hydroxycinnamates esterified into nascent and cell wall polysaccharides obtained from non-habituated (NH) and habituated to low DCB concentrations (1.5 μM; H) maize suspension-cultured cells.
Incipient DCB-habituated cell walls showed significantly higher levels of esterified ferulic acid and p-coumaric acid throughout the culture cycle. In terms of cell wall fortification, ferulic acid is associated to arabinoxylan crosslinking whereas the increase of p-coumaric suggests an early lignification response. As expected, the level of hydroxycinnamates esterified into nascent polysaccharides was also higher in DCB-habituated cells indicating an overexpression of phenylpropanoid pathway. Due to their key role in cell wall strengthening, special attention was paid into the dimerization pattern of ferulic acid. A quantitative comparison of diferulate dehydrodimers (DFAs) between cell lines and cell compartments revealed that an extra dimerization took place in H cells when both nascent and mature cell wall polysaccharides were analysed. In addition, qualitative differences in the ferulic acid coupling pattern were detected in H cells, allowing us to suggest that 8-O-4′-DFA and 8-5′-DFA featured the ferulic acid dimerization when it occurred in the protoplasmic and cell wall fractions respectively. Both qualitative and quantitative differences in the phenolic profile between NH and H cells point to a regioselectivity in the ferulate dehydrodimerization.
Structural model of the primary cell wall of dichlobenil-habituated maize suspension-cultured cells showing the interactions between cellulose, arabinoxylans and phenolic compounds. [Display omitted]
•Phenolic profile of DCB-habituated cells shows quantitative and qualitative features.•Intra-protoplasmic and cell wall extra dimerization occurs in DCB-habituated cells.•8-O-4′-DFA and 8-5′-DFA increases during DCB-habituation.•A regioselectivity in the ferulate dehydrodimerization is proposed.