Reassociation of a modified mycorrhiza with the host plant roots (Pinus radiata) and the transfer of acetylene reduction activity

Summary

Experiments were carried out to assess the potential for reassociation of modified strains of the mycorrhizal fungus Rhizopogon sp., capable of acetylene reduction activity in vitro, with the roots of its host plant (Pinus radiata). Reassociation was effected and acetylene reduction assays indicated that nitrogenase activity was present in the reassociated whole plants. Those host plants symbiotic with the modified strains had higher levels of nitrogen than those associated with the wild type fungus under nitrogen deprived conditions. Uptake of phosphate was unimpaired in the modified mycorrhiza. Electron microscopy showed that hyphae of the modified strains as well as lying in the intercellular spaces were often found within the cells of the root cortex. This was in contrast with the wild type strains where no such intracellular growth was found. One strain was sound to be pathogenic to seedlings of Pinus radiata. re]19760603