Healing and regeneration responses in Gigartina skottsbergii (Rhodophyta, Gigartinales): optimization of vegetative propagation for cultivation

摘要

This study reports the first attempt to determine the optimal conditions for vegetative propagation of G. skottsbergii (increasingly valuable as a raw material for the carrageenan industry) in the laboratory, with a view to alleviating the threat ofnatural stands collapsing under current levels of harvesting. The processes of wound healing and regeneration of frond fragments and haptera were studied under controlled conditions of temperature, light and media strength. The results demonstrated thatexcised tissues of G. skottsbergii were able to seal the exposed areas in approximately 20 days, by a wound healing process characterized by a re-differentiation of medullary cells into a normal cortex. The data also demonstrated that frond fragments are better than haptera for propagation purposes. The development of new cortical tissue at the cut surface was followed, within 60 days, by localized blade-like outgrowths along the repaired area. Furthermore, the healing and regenerative responses in both frond fragments and haptera differed in efficiency according to the various combinations of factors, with optima of 10-15deg C, a light level of 5μmol m-2 s-1 and plain seawater or standard SFC medium for the fronds. The 2 types of response were negatively affected by seawater enriched with a double concentration of nutrients.