Photomorphogenesis and Carbohydrate Changes in Etiolated Leaf Tissue

Abstract

The investigation of the biochemical aspects of photomorphogenesis has revealed an early response in carbohydrate metabolism following a brief exposure of etiolated plant tissue to red radiant energy (660 m[mu]). An enhancement of starch utilization may be observed by microscopic examination of leaf sections, and chemical assay reveals increased degradation of both starch and sugars. Furthermore, reversal of these observed decreases in carbohydrate content, determined as changes in total soluble sugars and starch content in etiolated corn seedling leaf sections, may be induced by a short exposure to far-red energy (730 m[mu]) immediately after a red treatment. Correlated with these biochemical responses there occurs a strong photomorphogenic leaf expansion. Carbohydrate changes may be one of the initial manifestations of phytochrome-mediated morphological reactions.