Phosphorus solubilization and uptake by dark septate fungi in fourwing saltbush, <i>Atriplex canescens </i>(Pursh) Nutt.

TitlePhosphorus solubilization and uptake by dark septate fungi in fourwing saltbush, Atriplex canescens (Pursh) Nutt.
Publication TypeJournal Article
Year of Publication2002
AuthorsBarrow J.R., Avila-Osuna P.
JournalJournal of Arid Environments
Date PublishedJuly 1, 2002
ARIS Log Number118666
KeywordsAtriplex canescens, fourwing saltbush, phosphorus solubilization, plant carbon, potential benefits
AbstractFourwing saltbush, Atriplex canescens (Pursh) Nutt., is an ecologically important range plant in arid southwestern USA rangelands. Native populations of this non-mycorrhizal, chenopodiacious shrub are extensively colonized by melanized dark septate fungi (DS). Seedling radicles of A. canescens are colonized at germination by a DS fungus identified as Aspergillus ustus that cannot be removed by heat or sterilization. The mutualistic association of A. canescens and A. ustus was evaluated by comparing plants treated with either no P (0P) or adequate plant available soluble P (30 ppm) in the root zone (AAP). Plant unavailable P (as rock phosphate (RP) or tricalcium phosphate (TCP)) was separated from the roots by a barrier that only allowed the passage of fungi. Plant roots in all treatments were internally colonized by A. ustus. A significant mutualistic response was observed in the RP and TCP treatments. Evidence for enhanced P uptake by the plant via the fungus was greater shoot and root biomass production and fungal density. Plants receiving P from plant unavailable P from TCP below the barrier via the fungus had equivalent shoot biomass and greater root biomass (P< 0.01) than plants receiving soluble P (AAP). Phosphorus use efficiency was increased in plants supplied P by fungi from plant unavailable P treatments. It was concluded that A. ustus utilized plant carbon for growth and the solubilization, uptake and transport of P to enhance shoot and root biomass. The potential benefits of DS fungi in arid ecosystems is discussed.