ROOT-SHOOT INTERACTION IN THE GREENING OF WHEAT SEEDLINGS CROWN UNDER RED-LIGHT

Wheat seedlings grown with roots exposed to constant red light (300-500 mu mol m(-2) s(-1)) did not accumulate chlorophyll in the leaves. In contrast, seedlings grown with their roots shielded from light accumulated chlorophylls. Chlorophyll biosynthesis could be induced in red-light-grown chlorophyll-deficient yellow plants by either reducing the red-light intensity at the root surface to 100 mu mol m(-2) s(-1) or supplementing with 6% blue light. The inhibition of chlorophyll biosynthesis was due to impairment of the Mg-chelatase enzyme working at the origin of the Mg-tetrapyrrole pathway. The root-perceived photomorphogenic inhibition of shoot greening demonstrates root-shoot interaction in the greening process.