1.8.22
THE ENDOPOLYGALACTURONASE GENE FAMILY OF BOTRYTIS CINEREA: ADAPTATION TO ENVIRONMENTAL CONDITIONS

JP WUBBEN1, W MULDER1, A TEN HAVE2, JAL VAN KAN2 and J VISSER1

1Section of Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, 6703 HA Wageningen, The Netherlands; 2Section of Phytopathology, Wageningen Agricultural University, Binnenhaven 9, 6709 PD Wageningen, The Netherlands

Background and objectives
The grey mould fungus Botrytis cinerea can infect over 200 different plant species, among which are many economically important crops. B. cinerea is an opportunistic pathogen that can invade damaged or senescent tissue. During infection the fungus secretes a number of cell wall-degrading enzymes including pectinases. Several reports have indicated that these pectinolytic enzymes can play an important role in the infection process by degrading the plant cell wall. We have initiated a molecular genetic approach to study the pectinolytic enzymes of B. cinerea in more detail.

Results and conclusions
We have isolated and characterized six different endopolygalacturonase (endoPG)-encoding genes from B. cinerea. The deduced amino acid sequences display different degrees of identity towards fungal endoPGs, including those produced by other plant pathogenic fungi. In order to study the physiological relevance of the presence of such a large number of endoPG genes in B. cinerea, we have analysed the expression patterns of each of the endoPG genes in liquid cultures under varying conditions. Induction of expression of some of the endoPG genes was observed using pectin-derived carbon sources such as polygalacturonic acid and galacturonic acid. Furthermore, pH of the culture medium influenced the expression levels/patterns of the endoPG genes. These data will be discussed in relation to the physiological relevance of the isozymes during infection. Analyses of the endoPG genes in planta will be described on the poster presented by ten Have et al.

This research is supported by the Dutch Technology Foundation (STW) project WBI 33.3046.