Isolation of theftsZ gene from plastid-deficient generative cells ofLilium longiflorum

Summary

In angiosperms, the pollen generative cell is the progenitor of the male gametes. In order to clone novel genes that are expressed specifically in male gametic cells, a simplified differentialdisplay method with total RNA was applied to isolated generative cells ofLilium longiflorum. At least three fragments were specifically amplified in generative cells in comparison with pollen and leaf cells. Northern blot analysis showed that one of these, which was named AP6-E, was part of a gene expressed strongly in generative cells. Reverse-transcriptase polymerase chain reaction analysis also revealed that the AP6-E gene was expressed during microsporogenesis and microspore development, and its expression was gradually reduced with pollen development. However, in situ hybridization demonstrated that transcripts of the AP6-E gene preferentially accumulated in the generative cell of nearly mature pollen. The isolation of AP6-E cDNA including an open reading frame of 468 amino acids showed that the AP6-E protein is a homolog of the plant plastid division protein FtsZ. This is the firstftsZ gene isolated from a monocotyledonous plant, and it suggests thatftsZ genes have a function other than plastid division, since generative cells contain no plastids.