Effect of auxin on cell wall glycanhydrolytic enzymes in epicotyls of Cicer arietinum

Abstract

Cell wall glycanhydrolytic enzymes have been related to cell wall loosening and cell growth, although the mechanism of this relationship has not been clarified. Since auxins are plant hormones that stimulate growth in elongating organs, in the present work we studied the effect of auxin on cell wall glycanhydrolytic enzymes, which were extracted with LiCl. Our results show that incubation of sections of Cicer arietinum epicotyls with indoleacetic acid elicit some minor changes in electrophoretic patterns of cell wall proteins when compared with control sections. This indicates that there is no appearance of a specific polypeptide synthesized de novo in response to the hormone, although there are increases in the intensity of some of the polypeptides, which could indicate an enhancement of wall protein biosynthesis. Brief incubation with IAA led to a general increase in the specific activities of these different cell wall enzyme fractions separated by chromatography, with the exception of the α‐fraction, with α‐galactosidase activity. Longer incubation resulted in an increase in the amount of protein associated with some of the enzyme fractions. In particular, it induced a large increase in the amount of protein associated with the β111‐galactosidase fraction that is involved in the autolytic process of cell walls of chick‐pea epicotyls. Our results indicate that auxin‐enhanced growth could be the result of the action of the hormone al the level of the cell wall glycanhydrolytic proteins that have been related to the wall‐loosening process.