MOLECULAR-CLONING AND CHARACTERIZATION OF A NEW BASIC PEROXIDASE CDNAFROM SOYBEAN HYPOCOTYLS INFECTED WITH PHYTOPHTHORA-SOJAE F-SP GLYCINES

Differential display techniques were used to isolate cDNA clones corre sponding to genes which were expressed in soybean hypocotyls by Phytop hthora sojae f.sp. glycines infection. With a partial cDNA clone C20CI 4 from the differential display PCR as a probe, a new basic peroxidase cDNA clone, designated GMIPER1, was isolated from a cDNA library of s oybean hypocotyls infected with P. sojae f.sp. glycines. Sequence anal ysis revealed that the peroxidase clone encodes a mature protein of 35 ,813 Da with a putative signal peptide of 27 amino acids in its N-term inus. The amino acid sequence of the soybean peroxidase GMIPER1 is bet ween 54-75% identical to other plant peroxidases including a soybean s eed coat peroxidase. Southern blot analysis indicated that multiple co pies of sequences related to GMIPER1 exist in the soybean genome. The mRNAs corresponding to the GMIPER1 cDNA accumulated predominantly in t he soybean hypocotyls infected with the incompatible race of P. sojae f.sp. glycines, but were expressed at low levels in the compatible int eraction. Soybean GMIPER1 mRNAs were not expressed in hypocotyls, leav es, stems, and roots of soybean seedlings. However, treatments with et hephon, salicylic acid or methyl jasmonate induced the accumulation of the GMIPER1 mRNAs in the different organs of soybean. These results s uggest that the GMIPER1 gene encoding a putative pathogen-induced pero xidase may play an important role in induced resistance of soybean to P. sojae f.sp. glycines and in response to various external stresses.