An agravitropic mutant of Arabidopsis, endodermal-amyloplast less 1, that lacks amyloplasts in hypocotyl endodermal cell layer

We have isolated a new recessive mutant of Arabidopsis thaliana for gravitr opism, endodermal-amyloplast less1 (eal1), eal1 shows reduced gravitropism in hypocotyl, and completely lacks gravitropism in inflorescence stems; roo t gravitropism is not affected. Starch staining with I-KI solution reveals almost no amyloplasts in call hypocotyls when grown on a sucrose-free mediu m, though the root columella cells contain as many amyloplasts as wild type , On a medium containing 1% sucrose, call hypocotyls contain as many starch granules as those of wild type, suggesting that starch synthesis is not af fected in eal1. The endodermal cell layer which is thought to function as s tatocytes in hypocotyls is present in call. These results suggest that diff erentiation or development of gravity-responsive amyloplasts are affected i n eal1 hypocotyls.