RELATIONSHIP BETWEEN LIGHT-INDUCED GROWTH-INHIBITION AND ACIDIC GROWTH-INHIBITORS IN THE SEEDLINGS OF DWARF AND TALL CULTIVARS OF PHASEOLUS-VULGARIS L

To clarify the role of endogenous inhibitors of growth in dwarf and tall bean plants, a search for specific inhibitors of growth was undertaken using the acidic substances of acetone extracts from the hypocotyls of dwarf (cv. Morocco) and tall (cv. Kentucky Wonder) bean seedlings (Phaseolus vulgaris L.). Two inhibitors were isolated from both cultivars and named A-1 and A-2, respectively, based on the order of their elution from a silica-gel column. Variations in the activity of the inhibitors in hypocotyls of both cultivars after the onset of red-light irradiation were determined using a bean bioassay, and the results were compared with those of red -light-induced inhibition of growth. The difference in the activity of A-1 and A-2 between the two cultivars was not great, and the changes with time in activity of A-1 and A-2 in hypocotyls of each cultivar did not reflect the light-induced inhibition of growth of hypocotyls of the same cultivar. These results suggest that acidic inhibitors, A-1 and A-2, are not involved in light-induced growth inhibition of the bean.