Compositional changes in cell wall polysaccharides from apple fruit callus

PAULA ALAYÓN-LUACES; NORA M. A. PONCE; LUIS A. MROGINSKI; CARLOS A. STORTZ; GABRIEL O. SOZZIC

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2012 vol. 185 p. 169 - 175

0168-9452

The cell wall composition of apples callus cultures showed changes in the presence of 5mg l−1 of threedifferent plant growth regulators (PGRs), namely picloram, abscisic acid and gibberellic acid. Although thestructural functions of cell walls do not generally allow for pronounced variations of the total pectin andmatrix glycan content, this work provides evidence that the addition of these plant growth regulators canrule, at least partly, cell wall metabolism in apple callus cultures. The chelator- and carbonate-extractsalways had the analytical characteristics of pectins, with high proportions of uronic acids, arabinose andgalactose as the main monosaccharides, and a significant proportion of rhamnose, but the cross-linkingglycan fractions were still rich in RG-I-like material. The application of PGRs produced shifts of uronicacid and neutral sugars between fractions. Arabinose was the neutral sugar exhibiting more variations inapple callus cell wall. Picloram and abscisic acid produced an increase of the uronic acid contents of thecell walls. The AIRs obtained from calluses treated with different PGRs did not show large amounts of highmolecular weight products, as determined by size-exclusion chromatography. For the carbonate-extractonly the callus treated with picloram displayed two separated peaks for products of different molecularweights. The chromatographic profiles for the 4% KOH-extract displayed two peaks for all the treatments,one very sharp with high molecular weight, and another one wider of smaller molecular weight, whereasthe difference between treatments can only be appraised through the areas of the peaks. This is the firstreport on cell wall composition from fruit calluses supplemented with different PGRs.