The Role of the Root in the Induction of Xylem Differentiation in Peas

Abstract

It is known that growing parts of the shoot induce the differentiation of vascular tissues below them and that this induction is due to the production of auxin. The problem dealt with here is why the formation of xylem proceeds in the growing roots. The redifferentiation of parenchyma to tracheary elements in grafts of pea plants was used in this study. It is proved that this is not due to stimuli coming from the root tip but rather to the movement of a stimulus coming from the shoot into the root. The polarity of movement is maintained even in thin sections, but it can be reversed by a strong shoot influence.