Development of infection structures of hemileia vastatrix on artificial membranes

Development of infection structures of Hemileia vastatrix on artificial membranes

H. G. Azinheira; M. C. Silva; L. Guerra Guimarães, K. Mendgen**, C. Rodrigues Jr. ; C. Pinto Ricardo*

Centro de Investigação das Ferrugens do Cafeeiro (IICT). Quinta do Marquês 2784-505 Oeiras, *Instituto de Tecnologia Química Biológica, Rua da Quinta Grande, 6, 2784-505 Oeriras. Portugal.
** Universität Konstanz, Fakultät für Biologie, Konstanz, Germany

Summary. Rust fungi differentiate a series of complex infection structures in order to successfully infect their hosts. The most striking difficulty to study obligate biotrophic fungi are the absolute need of host cell. Although the use of thigmotropically inductive membranes allowed the differentiation of infection structures in some rust, the ability of uredospores of the orange coffee rust to develop infection structures in the absence of its host plant is not known. In this work we evaluated a variety of membranes such as scratched polyethylene, coated membranes and collodion membranes supplemented with mineral oil as well as membranes sprayed with concanavalin A, boiled driselase and cell walls to induce differentiation in Hemileia vastatrix Berk. & Br. The development of infection structures was followed by light microscopy. On all the membranes assayed uredospores formed germination tubes and appressoria.

Keywords: Rust; Differentiation; Artificial membranes; Infection structures; Thigmodifferentiation.

Introduction

Infection by uredospores of rust fungi is preceded by development of specialized infection structures required for host penetration. The precise signal provided by the stoma to induce the fungal differentiation is not know. Dickinson (1949,1971) was the first to use artificial membranes to induce the development of infection structures. After his work, an increasing number of evidence has suggested that some physical characteristics of the stomatal structures are responsible for