Differential expression of pathogen-responsive genes encoding two types of glycine-rich proteins in barley.

Gene-specific probes (3' ends of cDNAs) were obtained from barley cDNAs encoding two types of glycine-rich proteins: HvGRP2, characterized by a cytokeratin-like and a cysteine-rich domain, and HvGRP3, whose main feature was an RNA-binding domain. Expression of genes Hvgrp2 and Hvgrp3, which are present at one (or two) copies per haploid genome, was ubiquitous and gene Hvgrp3 was under light/darkness modulation. Cold treatment increased Hvgrp2 and Hvgrp3 mRNA levels. Methyl jasmonate (10 microM) switched off the two genes. Expression of Hvgrp2, but not that of Hvgrp3, was induced by ethylene treatment (100 ppm). Fungal pathogens Erysiphe graminis and Rhynchosporium secalis increased the mRNAs levels of the two genes, both in compatible and in incompatible interactions, while bacterial pathogens did not.