首页 | 本学科首页   官方微博 | 高级检索  
     


Changes in Amino Acid Content and the Metabolism of γ-Aminobutyrate in Cucurbita moschata Seedlings
Authors:KUO-HOWERE CHOU  WALTER E. SPLITTSTOESSER
Affiliation:Department of Horticulture, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A.
Abstract: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, trans-location 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 acids and in the amino acids closely related to this 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.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号