Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

Epiphytic, IAA-producing bacteria strains were fed with ¹⁴C-tryptophan (Try). ¹⁴C-Try absorption and, after transfer to a Try-free medium, ¹⁴C-IAA output were stated. Using 4 different methods, the ¹⁴C-Try containing bacteria were applied to the tips of sterile corn coleoptiles and the ‘diffusible’ auxin collected at the coleoptile bases by means of agar blocks. ¹⁴C-IAA was detected in the agar blocks. Sterile coleoptiles the tips of which were wupplied with ¹⁴C-Try also deliver some ¹⁴C-IAA at their bases, but much less than both sterile coleoptiles supplied with ¹⁴C-Try-containing bacteria and nonsterile supplied with ¹⁴C-Try.