Utilize este identificador para referenciar este registo: http://hdl.handle.net/10451/11408
Título: Microbes made visible through plants : the functionality of piriformospora indica in the rhizosphere
Autor: Costa, Ana Raquel Teixeira da, 1989-
Orientador: Cruz, Cristina, 1964-
Palavras-chave: Micologia
Teses de mestrado - 2014
Data de Defesa: 2014
Resumo: Piriformospora indica is a root-colonizing endophytic fungus, belonging to the order Sebacinales (phylum Basidiomycota), that promotes plant growth and confers resistance against biotic and abiotic stresses. The colonization of barley (Hordeum vulgare) roots by this fungus begins with a biotrophic growth phase, followed by a necrotrophic phase in which root cells are actively killed by the fungus. In this work we subjected the fungus to various C concentrations and sources (glucose and sucrose) in order to understand how C availability and source influence its life strategy. By varying C/N ratios (but not the C source), two morphologically and physiologically distinct phenotypes were discerned: a “compact” phenotype (low C/N conditions) and an “explorer” phenotype (high C/N conditions). Our results showed that the compact phenotype of P. indica has a higher decomposition potential than the explorer phenotype. Next, both phenotypes were tested in two hosts: maize (Zea mays) and barley (Hordeum vulgare). When colonizing the hosts, the phenotypes were indistinguishable and readapted their physiology to their new environments. Furthermore, both phenotypes were exposed to root exudates and soil extracts (two important elements of the rhizosphere), as well to TiO2 nanoparticles (which had been suggested to enhance fungal performance) and again physiologically characterized. All three treatments affected the physiology of P. indica’s compact phenotype (low C/N conditions) but did not alter the normal physiology of P. indica’s explorer phenotype. While treatments with soil extracts and TiO2 nanoparticles exerted a repressor effect on the fungal decomposition potential, exposure to root exudates stimulated the fungus’ ability to decompose N and P. The functional characterization of P. indica’s phenotypes and the understanding of the environmental signals involved in its physiological changes will aid characterization of its functional role in the rhizosphere, and should be particularly useful for the improvement of inoculum production.
Descrição: Tese de mestrado. Biologia (Microbiologia aplicada). Universidade de Lisboa, Faculdade de Ciências, 2014
URI: http://hdl.handle.net/10451/11408
Aparece nas colecções:FC - Dissertações de Mestrado

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