Induction of a cDNA clone from rice encoding a class II small heat shock protein by heat stress, mechanical injury, and salicylic acid

This is the first report of a full-length cDNA clone for a class II small heat shock protein (sHSP) isolated from rice (Oryza sativa L., cv. Tainong No. 67) etiolated seedlings heat shocked at 41 °C for 2 h. The coding sequence consists of 501 bp, and the clone encodes a protein of 18.0 kDa with a predicted pI value of 5.61. The obtained full-length cDNA clone, designated Oshsp18.0-CII, is almost identical to a putative class II sHSP gene located on rice (cv. Nipponbare) chromosome one and another putative class II sHSP rice gene. Oshsp18.0-CII was induced by mechanical injury and salicylic acid treatment, which is not common in this class of sHSP genes. Only one copy of class II sHSP genes is present in the rice genome, and western blot analysis with anti-PsHSP17.7 (a class II pea sHSP) also showed only one protein of ∼18 kDa in the 2D gel of heat-shocked rice proteins. Oshsp18.0-CII is GC-rich and contains a secondary structure in its RNA sequence.