Cellulases and pectinases act together on the development of articulated laticifers in Ficus montana and Maclura tinctoria (Moraceae).

Abstract

The presence of articulated laticifers in the Moraceae family was recently discovered, which means that the location of pectinase and cellulase activities must be of great importance for their growth. Thus, the present study aimed to determine the role of these enzymes in the laticifer growth in Ficus montana and Maclura tinctoria. Reproductive meristems were collected and fixed in Karnovsky. Pectinase and cellulase labeling was performed in part of the samples, while another part was processed for usual TEM analyses. Pectinase and cellulase activities were detected in the vacuole and close to the middle lamella in both species. The presence of cellulases in the laticifers supports their articulated origin. Therefore, the occurrence of pectinase and cellulase activity in the laticifers points out that these enzymes could act in the dissolution of the transverse walls and in the processes of intrusive growth (through the dissolution of the middle lamella) and cell elongation (through the partial disassembly of components of the wall making it more plastic). Both enzymes are synthesized in the endoplasmic reticulum and transported to the cell wall by exocytosis or stored in the vacuole. The species studied showed a diverse subcellular composition, which is probably related to the species and not to the laticifer type (they present the same type) and to the composition of the latex (they show similar latex composition). We conclude that the presence of pectinases and cellulases can be used as a diagnostic condition for the laticifer types (articulated vs. non-articulated).