Quantitative Aspects of Nuclear Nucleoproteins

FACTORS CONTROLLING EMBRYO GROWTH AND DEVELOPMENT IN BARLEY (HORDEUM VULGARE L.)

Normal growth and development of barley proembryos occurred in excised intact florets, but not in ovaries from which lemmas and paleas were removed. The lemmas and paleas of the barley floret apparently contained a substance (referred to as "hull factor") which inhibited cell extension and stimulated cell division in the embryo. Evidence was obtained that this stimulation was not due to the provision of a simple energy source such as sucrose. In the absence of the "hull factor", ovaries cultured in vitro were found to contain embryos having nuclei in which the DNA content was equivalent to the tetraploid level, while mitosis was almost completely lacking. A similar embryo growth stimulation was obtained when a single leaf was left on an excised barley spike where lemmas and paleas were removed.