Inoculation of cranberry (Vaccinium macrocarpon) with the ericoid mycorrhizal fungus Rhizoscyphus ericae increases nitrate influx

Despite the ubiquitous presence of ericoid mycorrhizal (ERM) fungi in cranberry ( Vaccinium macrocarpon), no prior studies have examined the effect of ERM colonization on influx kinetics. Here, influx was measured in nonmycorrhizal and mycorrhizal cranberry in hydroponics. Mycorrhizal cranberry were inoculated with the ERM fungus Rhizoscyphus (syn. Hymenoscyphus) ericae. influx by R. ericae in solution culture was also measured. Rhizoscyphus ericae influx kinetics were linear when mycelium was exposed for 24 h to 3.8 m M, NH4+ and saturable when pretreated with 3.8 mM NO3- 50 mu M, or 50 mu M. Both low-N pretreatments induced greater influx than either of the high-N pretreatments. Nonmycorrhizal cranberry exhibited linear influx kinetics. By contrast, mycorrhizal cranberry had saturable influx kinetics, with c. eightfold greater influx than nonmycorrhizal cranberry at concentrations from 20 mu M to 2 m M. There was no influence of pretreatments on cranberry influx kinetics, regardless of mycorrhizal status. Inoculation with R. ericae increased the capacity of cranberry to utilize - NO3--N This finding is significant both for understanding the potential nutrient niche breadth of cranberry and for management of cultivated cranberry when irrigation water sources contain nitrate.