Cloning and analysis ofpsam2, a gene fromPisum sativumL. regulated in symbiotic arbuscular mycorrhiza and pathogenic root–fungus interactions

Abstract

A differential RNA display fragment was used to isolate a full size clone from a cDNA library prepared fromPisum sativumL. root RNA. The corresponding gene,psam2, belongs to a gene family and its RNA accumulation was repressed in roots after inoculation with the arbuscular mycorrhizal fungusGlomus mosseae. No significant changes in transcript levels could be observed in the nodule symbiosis formed withRhizobium. RNA accumulation was, however, enhanced after infection with two fungal root pathogens,Chalara elegansandAphanomyces euteiches.Phosphate or nitrate fertilization had no influence onpsam2RNA expression. Sequencing revealed that the putative gene product is similar to animal secretory carrier membrane proteins. Its possible involvement in changes in root exuded compounds after mycorrhizal formation or in secretion processes in phytopathogenic interactions is discussed.