Synthesis and turnover of cell-wall polysaccharides and starch in photosynthetic soybean suspension cultures

• Published in: Plant physiology (Bethesda) Vol. 111; no. 3; pp. 921 - 929
• Main Authors: Lozovaya, V.V. (University of Illinois, Urbana, IL.), Zabotina, O.A, Widholm, J.M
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.07.1996
• Subjects: ALMIDON; AMIDON; Biochemistry and Enzymology; Biological and medical sciences; Cell culture techniques; Cell growth; Cell lines; Cell walls; CELLULE; CELULAS; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; CRECIMIENTO; CROISSANCE; CULTIVO DE CELULAS; CULTURE DE CELLULE; Cultured cells; DIOXIDO DE CARBONO; DIOXYDE DE CARBONE; FOTOSINTESIS; Fundamental and applied biological sciences. Psychology; GLYCINE MAX; HEMICELLULOSE; HEMICELULOSA; ISOTOPE RADIOACTIF; LUMIERE; LUZ; Metabolism; METABOLISME DES GLUCIDES; METABOLISMO DE CARBOHIDRATOS; PARED CELULAR; PAROI CELLULAIRE; PECTINAS; PECTINE; PHOTOSYNTHESE; Photosynthesis, respiration. Anabolism, catabolism; Plant cells; Plant physiology and development; Plants; Polysaccharides; Radiocarbon; RADIOISOTOPOS; REGIME LUMINEUX; REGIMENES DE LUZ; SACCHAROSE; SOLUCIONES NUTRITIVAS; SOLUTION NUTRITIVE; Starches; SUCROSA; Cell culture; Light effect; Hemicellulose; Radiolabelling; Starch; Carbon dioxide; Autotrophy; Pectin; Metabolism; Glycine max; Carbon balance; Cell wall; Grain legume; Leguminosae; Mixotrophy; Dicotyledones; Angiospermae; Turnover; Spermatophyta
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.111.3.921

Soybean (Glycine max [L.] Merr.) suspension cultures grown under photoautotrophic and photomixotrophic (1% sucrose) culture conditions were used in 14CO2 pulse-chase experiments to follow cell-wall polysaccharide and starch biosynthesis and turnover. Following a 30-min pulse with 14CO2, about one-fourth of the 14C of the photoautotrophic cells was incorporated into the cell wall; this increased to about 80% during a 96-h chase in unlabeled CO2. Cells early in the cell culture cycle (3 d) incorporated more 14C per sample and also exhibited greater turnover of the pectin and hemicellulose fractions as shown by loss of 14C during the 96-h chase than did 10- and 16-d cells. When the chase occurred in the dark, less 14C was incorporated into the cell wall because of the cessation of growth and higher respiratory loss. The dark effect was much less pronounced with the photomixotrophic cells. Even though the cell starch levels were much lower than in leaves, high 14C incorporation was found during the pulse, especially in older cells. The label was largely lost during the chase, indicating that starch is involved in the short-term storage of photosynthate. Thus, these easily labeled and manipulated photosynthetic cells demonstrated extensive turnover of the cell-wall pectin and hemicellulose fractions and starch during the normal growth process