Grateloupia imbricata is an intertidal marine seaweed and candidate model organism for both industry and academic research, owing to its ability to produce raw materials such as carrageenan. Here we report on the transcriptome of G. imbricata with the aim of providing new insights into the metabolic pathways and other functional pathways related to the reproduction of Grateloupia species. Next-generation sequencing was carried out with subsequent de novo assembly and annotation using state-of-the-art bioinformatic protocols. The results show the presence of transcripts required for the uptake of glycerol, which is a specific carbon source for in vitro culture of G. imbricata and nucleotide sequences that are involved in polyamine-based biosynthesis, polyamine degradation, and metabolism of jasmonates and ethylene. Polyamines, ethylene and methyl jasmonate are plant growth regulators that elicit the development and maturation of cystocarps and the release of spores from seaweeds. Our results will inform studies of the mechanisms that control polysaccharide accumulation, cystocarp formation and spore release. Moreover, our transcriptome information clarifies aspects of red seaweed carposporogenesis with potential benefits for enhancing reproduction.