CONICET | Buscador de Institutos y Recursos Humanos

Different fungal isolates closely related to Zopfiella erostrata and Cercophora caudata have been found tocolonise plant root tissues in an asymptomatic way in the Monte Desert biome of La Rioja Province, Argentina. Thisinteraction has been newly discovered, and the role of these fungi in their desert habitat has never been studied in detail.The objective of this study was to evaluate eight fungal isolates by means of specific physiological traits that could haveimplications for their interaction with the host plant. The selected isolates, four endophytic and four rhizospheric, werecharacterised for their ability to produce indole acetic acid, solubilise and mineralise phosphorus (P), and utilisedifferent nitrogen sources. In addition, we evaluated organic acid production and phosphatase activities as mechanismsof P recycling. These analyses revealed that most isolates produced indole acetic acid, and that all isolates couldsolubilise and mineralise P, although to different degrees. Furthermore, the production of organic acids correlated withP solubilisation levels, which may enhance P availability in soils. Nitrogen utilisation was variable among the isolates,without specific patterns concerning the different sources and fungal isolates tested. Our results demonstrated that thefungal isolates had great variability, probably because they complete their teleomorphic phase in their habitats,generating viable meiotic spores, in addition to the active dispersion of these fungi by the underground rodent Ctenomysaff. knightii from which they were isolated. Although the isolates were variable, the endophytic isolates exhibitedimprovement in all the P parameters measured. This can be explained by the ability of these isolates to intimatelycolonise root tissues, while the colonisation by rhizospheric isolates is produced superficially in the rhizoplane. Thehigh occurrence of this interaction, as well as the physiological traits detected, suggest that this kind of fungi could playan important ecological role in the Monte Desert environment, benefiting the establishment and growth of newseedlings in areas occupied by the rodents.

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