Polar transport and metabolism of indole-3-acetic acid in tomato [Lycopersicon esculentum] stem

Polar transport and metabolism of indole-3-acetic acid in tomato stems were investigated using [2-sup(14)C] IAA. Polar transport was measured using the 2.5 cm sections of the upper part and the lower part of stems. The contents of IAA transport were about 4-7 times in the upper sections (3.0-5.8 pmol/ager/square cm) than in the lower sections (0.8 pmol/ager/ square cm) in the stems and moreover increased rapidly after 4.5 hours. (1.5-2 times). The transport speed which was calculated except for the content through the traffic channel of the vascular bundle was 0.67 cm per hour in the upper section of the stem. It was within the transport speed in general. However, the transport speed of the lower section could not be calculated. Metabolism was investigated using the 10 cm section of the middle of the stem. In the tip part, the upper part, the middle part and the lower part of the section treated with [2-sup(14)C] IAA for 24 hour, the radioactivity content was highest in the tip part and decreased to the lower parts. However, it increased a little in the lower part. As the cause of the increase of the radioactivity content, it was thought of the accumulated as the result of the polar transport or the existence of the other traffic channel (e.g. the vascular bundle). As the result from the liquid scintillation counter, the peak which corresponded to retention time of IAA (IAA correspond peak) wasn't detected, but a lot of peaks which were assumed as the metabolites of IAA (Metabolite peaks) were detected within 15 minutes. However, in the experiment to examine the decomposition content of IAA in the process of the extraction and purification using the tomato section, the content of Metabolite peaks was higher than IAA correspond peak. Therefore, it was thought that the influences such as the heating in the concentration process caused the resolution and that [2-sup(14)C] IAA changed to metabolite completely.