New phenomenon in early development of sporelings inGracilaria asiatica Chang et Xia (Gracilariaceae, Rhodophyta)

Abstract

Study on the early development of sporelings from carpospores ofGracilaria asiatica Chang et Xia was conducted indoors under controlled culture conditions. Besides normal development of sporelings, a new developmental phenomenon of filamentous frond was observed. It was composed of one or two rows of cells, and took place from the outmost brim of the basal disc. During the early disc stage of germinated carpospores, one or two filamentous fronds formed on about 10% basal discs. Simultaneously, young fronds began to arch slightly from the centers of single and coalescent discs; lately more filamentous fronds up to 80% appeared on the brims of basal discs. Meanwhile one or more upright fronds protuberated on the basal discs. Generally, filamentous fronds exhibited in self-existence or co-existence forms with normal young sporelings on the same basal disc, and single cell detached from filamentous fronds developed into a new filamentous frond. This new phenomenon exhibited a unique differentiation pathway during the early development ofG. asiatica, which would be potential for the application in artificial sporelings nursery.