نقش حفاظتي پلي آمين ها در برابر شوك گرمايي در رشد دانه رست هاي سويا

Protective role of polyamines against heat shock in soybean seedlings

Soybean (Glycine max (L.) Merr.) is a thermophilic plant. But the temperature up to 40°C inhibits its seed germination. In this research, the role of exogenous polyamines (putrescine, spermidine and spermine) in the heat-shock protection of soybean seedlings c.v Sahar was investigated. Also effects of pretreatment of polyamine inhibitor, on seedling growth were monitored. Results showed that exposure to heat-shock decreased growth whereas application of putrescine and spermidine increased thermo-tolerance and growth recovery. Similarly, lysine, an amino acid, was tested at equivalent concentration to demonstrate that heat- shock protection is really a polyamine phenomenon and not simply a growth effect from a source of nitrogen. The results showed that, polyamines did not act merely as a source of nitrogen when stimulating growth, suggesting stress adaptive role of polyamines. Pretreatment of polyamines plus biosynthetic inhibitors reduced the inhibitory effects and enhance growth recovery.