Expression of a salt-induced protein (SALT) in suspension-cultured cells and leaves of rice following exposure to fungal elicitor and phytohormones.

Phytohormones are essential signal compounds in the regulation of stress-related and defense-related genes. However, there is no clear evidence for any effect of these signal molecules and biotic elicitors on the regulation of the SALT gene in suspension-cultured rice cells. We characterized the expression of a SALT gene following treatment with fungal elicitor, phytohormones, cycloheximide, and inhibitors of protein kinase/phosphatases. SALT expression was up-regulated following treatment with a fungal elicitor, jasmonic acid (JA), abscisic acid (ABA), and NaCl. However, salicylic acid (SA) alone or in combination with one of the other elicitors not only strongly inhibited SALT gene expression but also exhibited an antagonistic effect in suspension cells and leaves. Cycloheximide inhibited SALT accumulation in suspension cells and in leaves, but the inhibitors of protein kinase/phosphatase did not. Immunolocalization revealed that SALT protein was present in xylem parenchyma cells of vascular bundles in the major and minor leaf veins.