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.