20 オーキシン極性移動阻害剤による黄化エンドウ上胚軸の自発的形態形成の誘導

抄録

Under true microgravity conditions in space as well as simulated ones on a 3-dimensional clinostat, epicotyls of etiolated pea seedlings have been demonstrated to be almost straight but the most to be oriented toward the direction far from their cotyledons with about 45 degrees from the vertical direction, being designated automorphosis. Kinetic studies revealed that in both seedlings grown under 1g and simulated microgravity conditions on the clinostat, epicotyls bent at their basal region or near cotyledonary node toward the direction far from the cotyledons with about 45 degrees within 36 hrs after watering. Thereafter epicoWls grew keeping this orientation under simulated microgravity conditions on the clinostat, whereas those grown on 1g conditions changed the growth direction to antigravity direction as negative gravitropic response. Treatment with inhibitors of auxin polar transport such as 2,3,5-triiodobenzoic acid (TIBA),N-(1-naphtyl)phthalamic acid (NPA) and 9-hydroxyfiuorene- 9-carboxylic acid (HFCA) induced automorphosis-like epicotyl bending, but that with p-chlorophenoxyisobutyric acid (PCIB), an inhibitor of auxin action, did not. These results suggest that auxin polar transport activity seems to be important for negative gravitropic response of epicotyls of etiolated pea seedlings on 1g conditions.