9. Phototropic sensitivity of coleoptiles of albino corn.


The mutant strain of corn, viviparous 5, is characterized by the production of seeds with white endosperm, which upon germination yield paper-white seedlings. Analysis of the coleoptiles of this mutant showed that they contained as much riboflavin as the normal but no detectable carotenoid pigments. Use was therefore made of the mutant in an attempt to decide between carotenoid pigments and riboflavin as the light receptor for phototropic curvature. Results showed that the mutant coleoptiles curved about one-half as much as the normals when exposed to blue light of sufficient intensity to elicit the first positive curvature in the normals. These results are interpreted to support the contention of Galston and co-workers that riboflavin is a light receptor pigment for phototropic curvature.


R. S. Bandurski and A. W. Galston