DIFFERENTIAL DISPLAY ANALYSIS OF RNA ACCUMULATION IN ARBUSCULAR MYCORRHIZA OF PEA AND ISOLATION OF A NOVEL SYMBIOSIS-REGULATED PLANT GENE

Differential RNA display was used to analyze gene expression during th e early steps of mycorrhiza development on Pisum sativum following ino culation with Glomus mosseae. Seven out of 118 differentially displaye d cDNA fragments were subcloned and sequenced. One fragment correspond ed to part of the fungal 25S ribosomal RNA gene and a second one showe d similarity to a human Alu element. The others were derived from plan t genes of unknown function. One of the fragments was used for the iso lation of a full-length cDNA clone. It corresponded to a single-copy g ene (psam1) which is induced during early symbiotic interactions, and codes for a putative transmembrane protein. Northern and RNA dot blot analyses revealed enhanced accumulation of psam1 RNA after inoculation with G. mosseae of wild-type pea and an isogenic mutant deficient for nodule development (Nod(-), Myc(+)).