Two cDNAs encoding pathogenesis-related proteins of Lithospermum erythrorhizon display different expression patterns in suspension cultures

Two cDNA clones, LePR1 and LePR2, encoding pathogenesis-related proteins we re isolated from shikonin-producing cells of Lithospermum erythrorhizon. Nu cleotide sequence analysis revealed that LePR1 and LePR2 contain open-readi ng frames coding for 156 and 154 amino acids, respectively. The LePR1 and L ePR2 cDNA clones share 93 % nucleotide and 90.4 % amino acid sequence ident ity in the coding region. The deduced amino acid sequences of LePR1 and LeP R2 show significant sequence homology with pathogenesis-related proteins, s uch as birch BetvI, parsley PR1-1, bean PvPR1, potato pSTH2, and soybean SA M22 and H4. Southern blot analysis indicates that LePR1 and LePR2 cDNAs cor respond to different genes that encode a small multigene family. Northern b lot analysis revealed that the expression of LePR1 is induced in cultured c ells at the stage of shikonin production. However, LePR2 is constitutively expressed, the corresponding mRNAs accumulating both in the cells cultured under shikonin-producing conditions and cells cultured under growth conditi ons. In addition, accumulation of LePR1 and LePR2 mRNAs was root-specific a nd enhanced by H2O2 and ABA.