The gene pyk20 which has been isolated from Arabidopsis thaliana encodes a
protein with a glutamine-rich domain in the C-terminal region. The transcri
ption of this gene was shown to be induced in feeding sites of root-parasit
ic nematodes (Heterodera schachtii), in roots infected by a fungus-like org
anism (Plasmodiophora brassicae), by plant hormone treatment, and by woundi
ng. In order to identify functional promoter regions seven different 5' and
3' pyk20 promoter (ppyk20) deletion fragments were fused to the uidA gene
(gus) and transformed into A. thaliana plants. Histochemical analysis of pl
ants containing the different ppyk20::uidA reporter constructs was performe
d during plant development in different plant tissues. Comparison of the pr
omoter deletion constructs showed that the region between -277 and -1 bp is
necessary to enhance the level of the GUS expression in nematode feeding s
ites and by plant hormone treatment. The region between -1912 and -278 is e
ssential to provide specificity of GUS expression. Conserved regulatory ele
ments were identified in the ppyk20 by sequence analysis. The activation pa
ttern of ppyk20 makes it well suited to engineer resistance against nematod
es and other pathogens. (C) 2000 Elsevier Science Ireland Ltd. All rights r
eserved.