Figure 7

JA insensitivity of tobacco plants expressing PpJAZ1. (a) Seeds from WT, Cl1 H, Cl2 G and Cl3 A were grown on MS agar without (upper panel) and with 25 μM MeJA (lower panel) for 4 days at 4°C and then for 12 days at 25°C. The growth of Cl2 G and Cl3 A roots was less inhibited by MeJA (25 μM) compared to WT E and Cl1 H. (b) Values of root lengths are the means of three replicates (12 seedlings each) with SE. Genotypes marked with asterisk (*) are significantly higher than WT E, according to Tukey-Kramer HSD (P <0.05). (c) The effect of long-term exposure to JA on root length was examined by growing the seeds on MS medium supplied with MeJA (50 μM) for 40 days. Transgenic plants from Cl2 G and Cl3 A continued to grow on MeJA containing medium and produced normal roots and shoots, indicating their insensitivity to MeJA, while WT and Cl1 H showed susceptibility to MeJA treatment. HSD, honest significant difference; JA, jasmonic acid; MeJA, methyl jasmonate; WT, wild type.