Flower-preferential poly(A) binding (PAB) protein gene from rice

The Poly(A) binding (PAB) protein functions in posttranscriptional regulation by stabilizing mRNA and initiating translation. Using sequence homology to Arabidopsis PAB genes, we have identified seven members (OsPAB1 through OsPAB7 ) of the PAB gene family in rice. These can be divided into two groups based on sequence identity and expression pattern. The four genes in the first clade*/OsPAB2 , OsPAB4 , OsPAB6 , and OsPAB7 */share strong homology with AtPAB2 , and are expressed in all the organs that were examined here. The remaining three, OsPAB1 , OsPAB3 , and OsPAB5 , show the specific expression pattern for flowering. OsPAB1 is expressed throughout floral development, although its level decreases as the flowers mature. In contrast, expression of OsPAB3 is evident in older flowers and developing seeds, while OsPAB5 transcript is present only in mature flowers. All the genes in the second clade are expressed in carpels and stamens, but not in the paleae and lemmae of spikelets. In addition, we have identified a T-DNA insertional line, in which the gus reporter gene is fused to OsPAB1 to produce the PAB1-GUS fusion protein. In those experiments, GUS staining was strong in the ovaries and anthers, demonstrating that OsPAB1 is preferentially expressed in the reproductive organs. # 2003 Elsevier Science Ireland Ltd. All rights reserved.