Typical results of descending and ascending temperature effects on T1/2 in individual cortical cells of Arabidopsis roots. T1/2 was continually measured in descending temperatures (25°C, 20°C, 15°C, and 10°C) for 10 min followed by ascending temperatures to 25°C. A, Wild type. B, PIP1;4-1. C, PIP2;5-1.