Altered cytokinin distribution in the shootless maize mutant ed*41

In seedlings of shootless ed*41 mutant of maize the distribution of cytokinin is strongly altered. Indeed, comparison between cytokinin immunolocalisation and cytokinin level clearly demonstrated that in the mutant the hormone did not reach the shoot apex zone. However, since an anomalous differentiation of vascular tissues has also been observed, a major role of the vascular connection in hormones translocation, hormone balancement and meristem origin and evolution has been proposed. Furthermore, an evident immunolocalisation signal of zeatin being only confined to root cap, cortex and vascular tissues allowed us to establish for the first time that the competence for the synthesis of this hormone in the root of both mutant and wild-type seedlings is tissue-specific. From the time-course evaluation of cytokinin distribution in the wild-type developing shoot it was possible to show that tunica and corpus zone reach the competence for these hormones in subsequent periods very probably in conjunction to photo-morphogenesis whereas this pathway is totally disrupted in the mutant. Hence on the basis of these results it is possible, for the first time, to relate the ed*41 mutation to both an inadeguate vascular connection and a hormone translocation.