After-effects of shoot or root heating on the thermotolerance of leaf and root cells in winter wheat seedlings

The patterns of thermotolerance development in root and leaf cells in winter wheat (Triticum aestivum L.) seedlings were studied for 5 h following the heating of either the shoot or root at 40 degrees C for 15, 30, and 180 min. After shoot heating terminated, leaf thermotolerance continued to increase for some time. After root heating, leaf thermotolerance remained at the level achieved during heating. High-temperature treatment of shoots and especially roots decreased root thermotolerance. When roots and shoots were separated immediately after root heating, the leaf tolerance pattern remained unchanged, as compared to the leaves of intact seedling, but the decrease in root tolerance was slowed. After shoot heating, the thermotolerance of the detached leaves developed more slowly than in the leaves of intact seedlings. The conclusion was drawn that plants responded to local heating and to its termination as an integral system, where shoots and roots mutually affect thermotolerance.