Isolation and characterization of a new defense gene from soybean

A cDNA clone of a single-copy gene designated SbPRP was isolated and charac terized from 2-week-old soybean seedlings. It putatively encodes a bimodula r protein similar to developmentally regulated proteins in other plant spec ies. The deduced amino acid sequence consists of 126 amino acids with a dis tinct proline-rich domain (17 amino acids) and a long hydrophobically cyste ine-rich domain (84 amino acids), plus a signal peptide of 25 amino acids i n N terminal. SbPRP mRNA transcripts accumulated in an organ specific manne r. It can be detected in leaves and epicotyls of soybean seedlings, whereas virtually expression signal of SbPRP was not detected in cotyledons, hypoc otyls and roots. Further Northern hybridization suggested that SbPRP steady -state mRNA level accumulated differentially not only in response to salicy lic acid, but to the inoculation of soybean mosaic virus Sa strain. Also it was responsive to drought treatment and salt (NaCl) stress. Therefore it i s likely that SbPRP functions as a defense gene in soybean.