Screening and preliminary analysis of an endosperm-specific expression gene in rice(Oryza sativa L.)

A promoter trapping line(accession no.w9101),in which the β-glucuronidase(GUS)reporter gene was endosperm-specific expression in both T0 and T1 generations,was identified from a promoter trapping population in rice(Oryza sativa L.ssp.indica).Genetic analysis and the Southern blot hybridization of the marker gene indicated that w9101 was a trapping line with a copy of T-DNA insertion.The flanking sequence of T-DNA insertion site was isolated by TAIL-PCR in w9101.The BLAST result of the sequence showed that the T-DNA insertion site was located in the promoter sequence of a putative peptide transporter gene in chromosome 6 of rice.It was tentatively named as PTR9101.RT-PCR analysis of the PTR9101 gene revealed that it was specifically expressed in rice endosperm.Further analysis by bioinformatics method indicated that the PTR9101 protein was hydrophobic with 12 α-helix membrane-spanning domain and similar to that of CHL1(The Nitrate Transporter AtNRT1.1)in Arabidopsis.It was thus concluded that PTR9101 was a hydrophobic peptide transporter gene.