cDNA cloning and expression analysis of the rice (Oryza sativa L.) RNase L inhibitor

A subtractive cDNA library was constructed using rice (Oryza sativa L.) callus cDNA as driver and differentiating callus cDNA as tester. A novel cDNA fragment encoding RNase L inhibitor (RLI) was isolated by screening the subtractive library, which had a higher expression level in differentiating callus than in callus. The full-length cDNA of rice-RLI was obtained by the method of rapid amplification of cDNA ends, which contained a 1812-bp open reading frame encoding a 604 amino acid polypeptide. Homologous analysis showed that rice-RLI contained the conserved motifs (two repeated P-loops, two ATP-binding boxes and an iron-sulfur binding motif). The fluorescence quantitative PCR analysis showed that it was a constitutive expressed gene but up-regulated in abiotic stress (low temperature and NaCl treatment) and down-regulated under the treatments of NAA and IAA.