Malaria is a major public health issue, responsible for 400 000 deaths every year. It is caused by Plasmodium parasites that circulate between vertebrate hosts and mosquito vectors. During this thesis, I focused on gametogenesis, a fascinating developmental stage to study Ca2+ signalling and regulation of the cell cycle in Plasmodium. Within seconds of activation, the cGMP- dependent protein kinase G (PKG) leads to mobilization of intracellular Ca2+. This is followed by a cascade of signalling events that in the male gametocyte regulates cell cycle progression to produce eight flagellated male gametes within ~10-12 minutes of the initial activation. I have identified a cGMP signalling platform involved in sensing extracellular cues activating gametogenesis and discovered a putative Ca2+ channel. Altogether my work sheds light into how Plasmodium transitions between host and vector and how it integrates and transduces cues from its environment to time its development.