Nucellar-cell-specific expression of a lipid transfer protein gene in barley (Hordeum vulgare L.)

Plant lipid transfer proteins (LTPs) are thought to participate in many aspects of cell growth and development. We have identified a novel LTP gene (LTP-ne) from barley (Hordeum vulgare) through differential screening of an ovary cDNA library. LTP-ne was mapped to the distal region of the long arm of barley chromosome 4, distinct from the genomic location of other known LTPs. Sequence comparison indicated that LTP-ne was more closely related to the 7-kDa LTPs than to the 9-kDa LTPs in barley. In Northern hybridization, LTP-ne transcripts were detected in ovary, but not in other tissues, and were most abundant 3-4 days after pollination. Furthermore, RNA in situ hybridization showed that within the ovary, the LTP-ne gene was specifically expressed in the outer cell layer of the nucellus. These results showed that the newly identified barley LTP was ovular cell specific and regulated by pollination/fertilization.