The differentiation of a vegetative cell and a generative cell is a critical event during pollen development. The Lilium GlsA is known to localize in pollen and is considered to be involved in development of the generative cell. Here, we cloned a glsA ortholog from Alstroemeria, a commercially important cut flower. The expression of AaglsA (Alstroemeria aurea glsA) transcripts increased gradually after pollen mitosis I (PMI) and reached a significant level when the generative cell started to elongate. Analysis of the promoter of AaglsA suggests that AaglsA expression is controlled by several cis-regulatory elements during pollen development. This is the first investigation of reproductive factors regulating male gametogenesis in Alstroemeria.