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Ungerminated pumpkin (Cucurbita moschata Poir.) cotyledons contained 30 % of their dry weight as lipid and 26 % as protein, of which 93 % was globulin. There was a rapid degradation of these reserves 4 to 8 days after planting when the cotyledons had their maximum metabolic activity. About half of the mole percent of amino acids found in the globulin reserve was in arginine, glutamate, aspartate, and their amides. The cotyledons had a large soluble pool of arginine, glutamine, glutamate, and leucine. Most amino acids increased steadily in amount in the cotyledons during germination, except glutamine, ornithine, alanine, serine, glycine, and γ-aminobutyrate and these appeared in large amounts in the translocation stream to the axis tissue. Little arginine or proline was translocated. By 10 days, when translocation had decreased, amino acids accumulated. Ornithine, γ-aminobutyrate, and aspartate were rapidly utilized in the hypocotyl, while glutamine, glycine, and alanine accumulated there. Cysteine and methionine levels were low in the reserve, translocation stream and soluble fractions. γ-Aminobutyrate-U-14C injected into cotyledons or incubated with hypocotyls was utilized in a similar fashion. The label appeared in citric acid cycle, but the bulk of the label appeared in CO2. The labeling pattern suggests that γ-aminobutyrate was utilized via succinate, and thus entered the citric acid cycle. A close relationship between arginine, ornithine, glutamate, and γ-aminobutyrate exists in the cotyledon with all but arginine being translocated rapidly to the axis tissue where these amino acids are rapidly metabolized. [ABSTRACT FROM AUTHOR]

Autoradiography, a technique combining radiochemistry, microtechnique and photography, offers another method for studying the morphology, physiology and cytology of plants. As applied to higher plants, the technique has not been thoroughly investigated; however, autoradiograms have been made that show not only good cellular detail but also developed grains of high photographic resolution associated with the cell components. The techniques of autoradiography in plants should be useful in elucidating such problems as organic transport, inorganic absorption and the pathway involved in absorption, cytological incorporation and synthesis in plants. [ABSTRACT FROM AUTHOR]