A, Seedlings of rsw2-1 transformed with an 8.5-kb cosmid containing the KOR gene do not show radial swelling when transferred to 31°C for 2 d after 5 d at 20°C. From the left: wild type, rsw2-1 transformed with KOR, and rsw2-1. B, F1 plants from crossing kor-1 and Columbia wild type (left) compared with F1 plants from crossing kor-1 and rsw2-1. Growth for 5 d at 20°C (when the position of the root tip was marked) and 2 d at 31°C. The kor-1/rsw2-1 plants show reduced elongation at 31°C (with accompanying clustering of root hairs) and a slight increase in diameter. Hypocotyls and petioles are also shorter.