In order to investigate the transportation and distribution of salicylic acid （SA） from root to aboveground tissues in response to high temperature, the roots of grape plant were fed with 14C-SA before high temperature treatment. Radioactivity results showed that progressive increase in SA transportation from root to aboveground as compared with the control varied exactly with the heat treatment time. Radioactivity results of leaves at different stem heights indicated that the increase in SA amount at the top and middle leaves during the early period was most significant in comparison with the bottom leaves. The up-transportation of SA from root to aboveground tissues was dependent on xylem rather than phloem. Autoradiographs of whole grape plants strongly approved the conclusions drawn above. Root-derived SA was believed to be a fundamental source in response to aboveground high temperature.
