Seeds from control or homozygous transgenic plants were sown on quartz sand and filter paper saturated with water (control), mannitol (350 mM) or NaCl (150 mM), respectively, for osmotic and salt treatments. For heat treatments, seeds were also sown on quartz sand and filter paper saturated with water and then moved to 30°C. (a) Seed germination rates under normal conditions. (b) Seed germination rates under osmotic stress. (c) Seed germination rates under heat stress. (d) Seed germination rates under salt stress. Error bars indicate SD; n = 4. Control, vector control plants; A2, A4, B1, C1.1, C2.1 represent the GmHsp90A2, GmHsp90A4, GmHsp90B1, GmHsp90C1.1 and GmHsp90C2.1 transgenic lines, respectively.