A root-growth-inhibitor found in Cucurbita endosperm

Abstract

In higher plants, the fertilization is fcllowed by the development of embryo and endosperm. Recently, many papers have reported that the development of embryo is influenced by the substances in endosperm. The isolated embryos of Cucurbita moschaia as young as 25-30 days after poliln., tlon were germinated and well grown ile viiro under aseptic condition on an agar medium, which contains 2% sucrose and mineral salts (pH 5.6). But on a medium added water extract of Cucurbita endosperms which was collected from seeds as young as 10-20 days after pollination, the roots of young seedling was inhibited to develop., the cortex in the root was broken down, and epidermis was spilited open (T-able 1, Fig. 2 and3). Effects of pH and osmotic pressure of medium to root development were examined (Table 2 and 3), and the fact was found that the phenomena above-mentioned was r.ot occured by change of pH values and osmotic pressure of medium. Therefore, it seems that a root inhibitingsubstance is present in the endospem of Cucurbita seeds. The root growthwas inhibited on an agar medium contained heteroauxin (Tabl 4), but the phenomena in this case differed from that on the medium contained endosperm extracts. So that, it seems that the root-inhibitor is notthe same to auxin itself. The root-inhibitor was also proved as heat stable. It is s, u:pposed by the auther that the root-in-hibitor is connect-*d with the development of embryo (Fig 1.).