ISOLATION AND EXPRESSION PATTERN ANALYSIS OF RICE AUXIN-INDUCED eIF3a CODING GENE
LI Hong SHEN Si Shi XU Zhi Hong XUE Hong Wei ( National Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shangliai Institutes for Biological Science, The Chinese Academy of Sciences; Partner Group of Max-Planck-Inslitute of Molecular Plant Physiology on "Plant Molecular Physiology and Signal Transduction" , Shanghai 200032, China)
Eukaryotic initiation factors (eIFs) are key elements in protein synthesis. Among identified 13 initiation factors, eIF3, composed of 8 or more subunits, is the largest one and plays a central role in the initiation of translation. As the largest subunit, eIF3a mediates most functions of eIF3. Based on the experiments that rice eIF3a gene could be induced by auxin (through fluorescent differential display PCR), a cDNA coding for rice eIF3a, named OseIF3a\ , was isolated. OseIF3al cDNA, with a length of 3459bp (including 5' and 3'-UTR) and encoding a 986-aa polypeptide, shared sequence identity of 82. 4% and 70. 1 % with that in maize and tobacco. Comparison of cDNA and genomic sequence revealed the presence of 13 exons and 12 in-trons in OseIF3a1 gene. Reverse transcript PCR (RT-PCR) analysis indicated the expression of OseIF3a1 in root, shoots, young spike, stem and leaf tissues, promoter-GUS fusion studies further confirmed its expression in root tip, leaf, glume and stigma. The induction of OseIF3a1 by auxin suggested that function of auxin on growth may involve the regulation on translation level.