Effects of aflatoxin on seedling growth and ultrastructure in plants

Nineteen plants belonging to 11 species of the cruciferae were studied to determine the effects of aflatoxin B(1) on seed germination and seedling development. Germination was not inhibited in any test organism at a concentration of 100 mug of aflatoxin per ml of agar substrate. Inhibition of elongation of the hypocotyls and roots in the species studied varied from 29 to 93% and from 22 to 91% in the respective tissues. Lepidium sativum was the most susceptible plant studied and exhibited the maximal inhibitory response noted above at concentrations of 8 mug of aflatoxin per ml. The ultrastructure of Lepidium root cells treated with crystalline aflatoxin B(1) exhibited morphological changes characteristic of those found in aflatoxin-treated animal cells. In addition to changes in the cytoplasmic organelles, numerous ring-shaped nucleoli with prominent nucleolar caps were produced. The effect of aflatoxin on plant cells is compared with similar effects induced by actinomycin D. Seed germination and seedling development is discussed in relation to the effects of both compounds on deoxyribonucleic acid-dependent ribonucleic acid biosynthesis.