L-Tryptophan metabolism in wound-activated and Agrobacterium tumefaciens-transformed potato tuber cells.

The in vivo metabolism of L-tryptophan in wound-activated and Agrobacterium tumefaciens, strain C 58, transformed tissues of white potato tubers (Solanum tuberosum L. cv. Saskia) was investigated. The following metabolites of L-tryptophan were identified in both tissues by co-chromatography with authentic standards in several thin- layer chromotography (TLC) and high pressure liquid chromatographic (HPLC) systems: indolc-3-acetic acid (IAA), indole-3-acctaldehyde, indole-3-ethanol, indole-3-acctamide and tryptamine. Labelled indole-3-acetaldoxime was only found in transformed tissue. Crown gall tissue generally incorporated [14C]-L-tryptophan into pre- cursors of IAA at a distinctly higher rate than did wound tissue. Tryptamine and in- dole-3-ethanol accumulated about ten-fold more label in crown gall cells than in cells from wounded tissue. The incorporation of radioactivity into indole-3-acctamide as determined by 2 consecutive TLC systems followed by HPLC analysis was rather low, though consistently observed in both tissues. An indole-3-acetamide hydrolyzing enzyme, the putative product of gene 2 on the T-DNA. could be extracted from the transformed tissue only. The indole-3-ethanol level was 4.3 nmol (g dry weight)-1 and 41 nmol (g dry weight)-1 for wounded tissue and primary crown gall tissue, respectively, as determined by HPLC with a [14C]-labelled internal standard. The experiments are critically discussed in relation to recent reports on a T-DNA encoded enzyme of IAA biosynthesis in crown gall tumors. [ABSTRACT FROM AUTHOR]