Abstract
The tapetum is believed to play important roles for maturation of pollen grains, but many of its functions have not been uncovered yet. To reveal such functions by reverse genetics, tapetum-specific promoters are good tools. However, few such promoters have been reported. We analyzed a promoter of GRP17, which encodes a protein accumulating specifically in tapetal cells. A 150 bp fragment upstream from initiation codon was sufficient for tapetum-specific expression. This promoter activity was abolished by base substitutions in a motif conserved among GRP gene promoters, suggesting that this motif might be a target site of tapetum-specific transcription factors. Some lipid transfer proteins (LTP), which are involved in lipid metabolism and transfer, act only in the tapetum. Their promoters worked specifically in tapetal cells at different stages of pollen development.
