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Side chains of pectic polysaccharides are regulated in relation to cell proliferation and cell differentiation
Author(s) -
Willats William G. T.,
SteeleKing Clare G.,
Marcus Sue E.,
Knox J. Paul
Publication year - 1999
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1999.00629.x
Subject(s) - galactan , cell wall , meristem , microbiology and biotechnology , elongation , cell , xyloglucan , cell growth , polysaccharide , biology , cell culture , cellular differentiation , cell division , epitope , biochemistry , antibody , immunology , materials science , genetics , ultimate tensile strength , metallurgy , gene
Summary The occurrence and function of the side chains occurring in the rhamnogalacturonan I domain of pectic poly‐ saccharides have been investigated during carrot cell development using monoclonal antibodies to defined epitopes of (1→4)‐β‐D‐galactan and (1→5)‐α‐L‐arabinan. Immunolocalization studies of carrot root apices indicated that cell walls in the central region of the meristem contained higher levels of (1→5)‐α‐arabinan than the cell walls of surrounding cells. In contrast (1→4)‐β‐galactan was absent from the cell walls of the central meristematic cells but appeared abundantly at a certain point during root cap cell differentiation and also appeared in cell walls of differentiating stele and cortical cells. This developmental pattern of epitope occurrence was also reflected in a suspension‐cultured carrot cell line that can be induced to switch from proliferation to elongation by altered culture conditions. (1→4)‐β‐galactan occurred at a low level in cell walls of proliferating cells but accumulated rapidly in cell walls following induction, before any visible cell elongation, while (1→5)‐α‐arabinan was present in cell walls of proliferating cells but was absent from cell walls of elongated cells. Immunochemical assays of the cultured cells confirmed the early appearance of (1→4)‐β‐galactan during the switch from cell proliferation to cell elongation. Anion‐exchange chromatography confirmed that (1→4)‐β‐galactan was attached to acidic pectic domains and also indicated that it was separate from a distinct homogalacturonan‐rich component. These results indicate that the neutral components of pectic polysaccharides may have important roles in plant cell development.