Oligosaccharides with regulatory effects on living plant tissue have been obtained by partial hydrolysis of xyloglucan, cellulose and pectic polysaccharides. Attention is focused here on xyloglucan-derived oligosaccharides (XGOs), which exert the following two distinct effects on cell growth in pea-stem segments. (i) At approx. 1 nM, the L-fucosylated XGOs, such as XXFG, XFFG and FG (for structure of XXFG, see Fig. 1), antagonize 2,4-dichlorophenoxyacetic acid (2,4-D)-stimulated growth. At approx. 100 nM, XXFG loses this growth-inhibitory effect, probably because it gains a growth-promoting effect [see (ii)]; in contrast, FG retains its growth-inhibitory effect. The growth-inhibitory effect is tentatively attributed to membrane-binding of the active XGOs. (ii) At approx. 1 mu M, at least four different cellotetraose-based XGOs (XXXG, XXLG, XXFG and XLLG) mimic auxin in that they induce growth. This effect is thus not L-fucose-dependent and is not exhibited by the cellobiose-based pentasaccharide, FG. Effect (ii) is attributed to the ability of cellotetraose-based XGOs to act as acceptor substrates for xyloglucan endotransglycosylase.
|Title of host publication||MOLECULAR BOTANY: SIGNALS AND THE ENVIRONMENT|
|Editors||DJ Bowles, PM Gilmartin, JP Knox, GG Lunt|
|Place of Publication||LONDON|
|Number of pages||10|
|Publication status||Published - 1994|