Root exudate-stimulated RNA accumulation in the arbuscular mycorrhizal fungus Gigaspora rosea

Plant root exudates induce the transition from asymbiosis to presymbiosis in arbuscular mycorrhizal fungi. In order to get an insight into this developmental switch, two libraries of Gigaspora rosea and one library of Gigaspora gigantea were screened for fragments of genes that show enhanced RNA accumulation 1 h after addition of a semi-purified exudate fraction of carrot roots. Among 150 clones, 40 seemed to contain inserts of root exudate-induced genes. One of the genes, GrosRbp1, putatively encoding an RNA binding protein involved in developmental control showed RNA accumulation which correlates to the extent of stimulation of presymbiotic hyphal branching.