Abstract
In vitro cell wall-autolysis assays with Zinnia culture system have demonstrated that pectin is one of the most actively degraded substances during tracheary elements (TEs) differentiation. To understand modification of cell walls during TE differentiation, we have isolated and analyzed three Zinnia polygalacturonase (PG) genes, ZePG1-ZePG3. Among these genes, ZePG2 and ZePG3 were specifically up-regulated at 60 h of culture in the TE-inductive medium. We generated a rabbit antibody against the ZePG2 protein, and examined the expression of this protein during TE differentiation. The ZePG2 protein appeared at 48 h and increased rapidly for next 12 h. This analysis also suggested that the ZePG2 protein may be processed during TE differentiation. Analysis of subcellular localization of the ZePG2 protein is underway, and taken together we will discuss the function of polygalacturonases in TE differentiation.