Signalling between arbuscular mycorrhizal fungi and plants: identificationof a gene expressed during early interactions by differential RNA display analysis

Although there is evidence for an interplay of signalling/recognition event s at different stages during plant/fungal interactions in arbuscular mycorr hiza, the nature of signalling molecules and signal perception/transduction processes are so far unknown. Virtually nothing is known of molecular inte ractions during initial contact between arbuscular mycorrhizal symbionts, b ut plant mutants which limit fungal development to these first steps (myc(- 1)) provide proof of the involvement of plant genes. One such pea mutant (P 2) has been used to investigate gene expression during early plant-fungal i nteractions by differential RNA display. Partial transcriptome analysis has indicated frequent similarities in up-regulated genes in Glomus mosseae-in oculated mutant and non-mutant pea genotypes. One of these has been putativ ely identified as a plant Clp serine protease and its eventual role in earl y events of arbuscular mycorrhiza interactions is discussed.