Studies on embryo Culture in plants. : I On the action of auxln and embryo factor on embryonic growth .

Abstract

It is necessary to make clear the action of embryo factor which is closely related to growth of the very young embryo in plants, for establishing the technique of ile vitro culture of the plant embryo. In this report, the author has studied action of auxin and embryo factor on embryonic growth. The growth of embryo of cucumber in a medium containing malt extract or Cucurbita endosperm extract, showed the existance of embryo factor in malt extract and also Cucurbita endosperm extract (cf. photo. 2) . By means of avena curvature method, it was shown that embryo and endosperm of Cucurbita makima contained the free auxin and bound auxin (alkali released) at all stages of seed development (cf. table l). and also the above mentioned malt extract and endosperm extract of Cucurbita contained both the free a ?? d bound auxin (cf. table 2). Therefore, the author thinks t'nat the auxin plays a very important role in the growth of embryo. Then the growth of embryo of cucumber (1ate heat stage-early torpedo stage) in a medium containing IAA and also in a medium containing embryo factor, had been compared from morphological and histological point of view. In morphological observation, the, fomer (only high concentration ; IAA 2 ppm. ) was similar to the later (cf. table 3) . In histological observation, only cell elongation was recog, nized in using IAA, but in using embryo factor, both the cell elongation and cell division were recognized (photo 3, 4) . And then, the existance of starch grain in the cells of cultured embryo showed that the action of embryo factor is related to the action of auxin. So the author thinks the embryo factor contains auxin and other factors which accelerate the cell division in plant embryo.