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Universidade de Lisboa (2019)

Study of bacteria involved in Acacia longifolia nodulation : influence of fire on symbiosis establishment

Jesus, Joana Guedes de

Titre : Study of bacteria involved in Acacia longifolia nodulation : influence of fire on symbiosis establishment

Auteur : Jesus, Joana Guedes de

Université de soutenance : Universidade de Lisboa

Grade : Mestrado, Microbiologia Aplicada, 2019

Résumé partiel
Acacia longifolia is an invasive leguminous species that can cause a considerable damage in the ecosystems. This species, native from coastal dunes of southern Australia, was brought to Portugal for dune stabilization, preserve sand erosion and ornamental purposes, competing with native plants for natural resources and changing the soil characteristics. The expansion of this species, in the last decades, caused an environmental impact, in particularly in the Portuguese coastal dunes. Several factors potentiate its expansion, namely fires that occur frequently and promote seed germination. Furthermore, high colonization success of A. longifolia is related to its association with nitrogen-fixing bacteria, that develop inside root nodules, where fixation occurs. These bacteria, belonging mainly to the Rhizobiaceae family are determinant in plants’ growth. Out study aimed to understand (1) which bacteria (genus/species) are present in the symbiosis ; (2) if fire will alter the bacterial community established in the nodules ; and (3) nodule morphological characterization. Nodules from 20-60 cm long young plants of A. longifolia were collected in the field in unburnt zone and burnt zone (one-year after fire). For bacterial isolation, disinfection protocol was applied in nodules and a total of 152 bacterial isolates were obtained in YMA growth medium. DNA was extracted and genomically fingerprinted by PCR amplification with M13 and GTG-5 universal primers. Assessment of diversity was based on dendrograms with Pearson similarity coefficient and UPGMA.

Mots clés  : Acacia longifolia Nódulos Fogo Azoto Bradyrhizobium sp

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