Abstract

A cDNA clone which encodes a cysteine protease inhibitor gene, named PsCPI, has been identified in Polygonum sibiricum Laxm. by the rapid amplification of cDNA ends method (RACE). Analysis of the nucleotide sequence reveals that the PsCPI gene cDNA clone consists of 437 bp, containing 38 bp in the 5' untranslated region, 336 bp in the open reading frame (ORF) encoding 111 amino acids and 63 bp in 3' untranslated region. The gene accession nucleotide sequence number in GenBank is GU562861. Expression analysis by real-time quantitative PCR reveals that the PsCPIgene is expressed in leaves, stems and rhizomes. The result shows that PsCPI gene expression can be induced by 3% NaHCO₃ in the three earlier mentioned tissues, but there are different expression modes in leaves, stems and rhizomes under the salinity-alkalinity stress.

Keywords: Polygonum sibiricum Laxm., Polygonum sibiricum Laxm cysteine protease inhibitor, rapid amplification of cDNA ends, real-time polymerase chain reaction, gene expression.

Abbreviation

CPI, Cysteine protease inhibitor; EST, expressed sequence tag;cDNA, complementary DNA; RACE, rapid amplification of cDNA ends; PsCPI,Polygonum sibiricum Laxm cysteine protease inhibitor; PCR, polymerase chain reaction; ORF, open reading frame; UTR, 5'-untranslated region; PCD, programmed cell death.