Impact of galactoglucomannan oligosaccharides and Cd stress on maize root growth parameters, morphology, and structure.

Biologically active oligosaccharides, including galactoglucomannan oligosaccharides (GGMOs), affect plant growth and development. The impact of GGMOs is dependent on their concentration, and the plant species and plant parts affected. The aim of this article is to ascertain the effects of GGMOs, GGMOs + Cd2+, on growth parameters, morphology, and the structure of maize (Zea mays L.) roots. We undertook this research because, in monocots, the effect of these oligosaccharides is so far unknown. In our study, GGMOs stimulated primary root elongation, induction and elongation of lateral roots, and biomass production. Their effect was dependent on the concentration used. Simultaneously, GGMOs moderated the negative effect of Cd2+ on root elongation growth. Besides, GGMOs affected the primary root structure, proven in the earlier development of xylem and Casparian bands, but not of suberin lamellae (compared to the control). The presence of Cd2+ shifted the apoplasmic barriers closer to the root apex in comparison to samples treated with GGMOs + Cd2+. GGMOs do not inhibit Cd uptake into the root directly, but they moderate its effect, and therefore their influence at the structural and metabolic level seems possible. Their positive impact on plant vitality, even in contaminated conditions, strongly indicates their potential application in remediation technologies.