Fig. 1.

Embryogenic and gametophytic developmental pathways of the microspore. Scheme representing the main stages of the two developmental pathways that the microspore can undergo. (A) Embryogenic pathway: by stress treatment in vitro, the vacuolated microspore is reprogrammed and follows an embryogenic pathway forming embryos that further regenerate haploid and double-haploid plants. (B) Gametophytic pathway: in vivo, the microspore undergoes the gametophytic development leading to mature pollen which further germinates and carries out fertilization.