Salt tolerance imparted by SOS1. The 7-d-old seedlings of two independent Nipponbare transgenic lines expressing 35S:SOS1 were cultivated alongside control seedlings transformed with an empty vector (V) in the absence or presence of 25 and 50 mm NaCl for 4 weeks. A, Representative control (V) and transgenic plants (SOS1) are depicted. B, Survival rate of plants after the completion of the experiment. C, Dry weight (DW) and Na⁺ content (as percentage of DW) of plants surviving the 25-mM NaCl treatment (n = 6). Letters indicate significantly different values relative to that in the wild type determined by one-way ANOVA (a = P < 0.01, b = P < 0.05, c = P < 0.1).