Ecological and physiological investigations on Eichhornia crassipes (MART.) SOLMS. II. Studies of root structure and the dependance of pigment deposition on the age and physiological state of the roots

The Amazonian water hyacinth, E. crassipes, a Pontederiaceae, is a rarity among higher plants due to the production of blue colour in its roots in response to nitrogen deficiency in the medium. Qualitative and quantitative aspects of pigment deposition in the various root regions, from epidermis to hypodermis, throughout the entire primary cortex, is described. By determining the activity of three enzymes of the pentosephosphate cycle and the shikimate pathway, in combination with the successive pigment deposition in the cell qalls, it has been shown that de novo synthesis must occur and that the pigments are probably anthocyanin-like compounds. A possible ecological function of the deposition of secondary products in the roots is discussed