Alteration of pectic polysaccharides in cell walls, extracellular polysaccharides, and glycan‐hydrolytic enzymes of growth‐restricted carrot cells under calcium deficiency

Abstract

Suspension‐cultured carrot (Daucus carota L. cv. Kintoki) cells were grown in calcium (Ca2+)‐deficient and normal liquid media. Cell growth was limited by the Ca2+ deficiency. Similar amounts of pectic fractions were extracted from the walls of control and Ca2+‐deprived cells, but the fractions from the walls of Ca2+‐deprived cells showed a substantial decrease in galacturonic acid content. However, after 15 days of culture, Ca2+‐deprived cells released galacturonic acid‐rich extracellular polysaccharides at twice the rate of control cells. The polysaccharides consisted of a mixture of several polymers containing predominantly arabinose, galactose and galacturonic acid. Ca2+‐deprived cells also secreted three times more extracellular proteins, containing many glycan‐hydrolytic enzymes, into the medium than did normal cells. SDS‐PAGE analysis revealed several distinct changes in the polypeptide pattern in the medium of control and Ca2+‐deprived cells. Activities of α‐galactosidase, β‐glucosidase and exo‐polygalacturonase increased considerably during Ca2+ deficiency, whereas α‐ l‐arabinofuranosidase and β‐galactosidase activities were much reduced.

Effects of cytokinins on in vitro mineral accumulation and bud development in Annona glabra L.

“…Calcium is directly involved in the processes of cell division in the meristematic zones of plants, affecting their viability and bud formation and, consequently, the plant's multiplication rate. Calcium also participates in the synthesis of pectin molecules involved in cell wall formation (Konno et al, 1999), and the lack of this element may alter the structure and metabolism of the pectin molecules, reducing the mitotic index in these plants. Additionally, reduction of the calcium content in tissues cultivated in vitro is directly related to physiological disorders such as necrosis of the apex and vitrification.…”

“…Nitrogen is essential for normal growth and development in plants, and plays an important role in regulating of many physiological functions (Konno et al, 1999;Ramage & Williams, 2002). Leljak-Levanic et al (2004) demonstrated that NH 4 + and NO 3 -concentrations in the culture medium affect numerous morphogenetic responses, including the development of callus tissue and somatic embryos.…”

Metal-tolerant moss Scopelophila cataractae accumulates copper in the cell wall pectin of the protonema

“…Calcium plays an important role in regulating the structure and properties of the network of pectic molecules in cell walls. Apoplastic Ca regulates the deposition of non-cellulosic polysaccharides in cell walls of spruce (Eklund and Eliasson, 1990) and flax hypocotyl (His et al, 1997) seedlings and carrot cell cultures (Konno et al, 1999). However, since Ca was found in almost similar amounts in the control and Cu-treated cell walls, the difference in the pectin extraction from the two cell walls could not be due to a difference in the Ca concentration in the cell walls.…”

Increased Calcium Levels and Prolonged Shelf Life in Tomatoes Expressing Arabidopsis H+/Ca2+ Transporters

“…Cell wall-associated Ca 21 maintains cell wall integrity by generating cross-links with nonesterified pectins in the primary cell wall and middle lamella (Jarvis, 1984;Poovaiah et al, 1988 -pectin bridges prevents the access of cell wall hydrolytic enzymes, thus inhibiting cell wall expansion (Jauneau et al, 1994;Konno et al, 1999). Further work is required to demonstrate that cell wall-associated Ca 21 levels are indeed enhanced in CAX-expressing plants compared to wild type.…”