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Resumen de la comunicación oral presentada en: 9th Workshop Advances in Science and Technology of Bioresources. Univ. De la Frontera, Temucho, Chile. 29 noviembre - 1 diciembre (2022), Project RTI2018-098756-B-I00 and RTI2018-094350-B-C31 funded by MCIN/ AEI /10.13039/501100011033/ and by FEDER Una manera de hacer Europa

Resumen de la conferencia presentada en: I Spanish-Portuguese Congress on Beneficial Plant-Microbe Interactions (BeMiPlant) and XVIII National Meeting of the Spanish Society of Nitrogen Fixation (XVIII SEFIN). Oeiras, Portugal, 17-19 octubre 2022., Project RTI2018-098756-B-I00 and RTI2018-094350-B-C31 funded by MCIN/ AEI /10.13039/501100011033/ and by FEDER Una manera de hacer Europa.

Resumen del poster presentado en: I Spanish-Portuguese Congress on Beneficial Plant-Microbe Interactions (BeMiPlant) and XVIII National Meeting of the Spanish Society of Nitrogen Fixation (XVIII SEFIN). Oeiras, Portugal, 17-19 octubre (2022), Project RTI2018-098756-B-I00 funded by MCIN/ AEI /10.13039/501100011033/ and by FEDER Una manera de hacer Europa.

Resumen del poster presentado en: 11th International Conference on Mycorrhiza (ICOM11) 31 Julio - 5 de agosto Beijing, China

Phosphorus (P) is a poorly available macronutrient essential for plant growth and development and consequently for successful crop yield and ecosystem productivity. To cope with P limitations plants have evolved strategies for enhancing P uptake and/or improving P efficiency use. The universal 450-million-yr-old arbuscular mycorrhizal (AM) (fungus-root) symbioses are one of the most successful and widespread strategies to maximize access of plants to available P. AM fungi biotrophically colonize the root cortex of most plant species and develop an extraradical mycelium which overgrows the nutrient depletion zone of the soil surrounding plant roots. This hyphal network is specialized in the acquisition of low mobility nutrients from soil, particularly P. During the last years, molecular biology techniques coupled to novel physiological approaches have provided fascinating contributions to our understanding of the mechanisms of symbiotic P transport. Mycorrhiza-specific plant phosphate transporters, which are required not only for symbiotic P transfer but also for maintenance of the symbiosis, have been identified. The present review provides an overview of the contribution of AM fungi to plant P acquisition and an update of recent findings on the physiological, molecular and regulatory mechanisms of P transport in the AM symbiosis. This work was supported by Spanish Ministry of Science, Innovation and Universities (Project AGL2015-67098-R).

Arbuscular mycorrhizal (AM) fungi can improve iron (Fe) acquisition of their host plants. Here, we report a characterization of two components of the high-affinity reductive Fe uptake system of Rhizophagus irregularis, the ferric reductase (RiFRE1) and the high affinity Fe permeases (RiFTR1-2). In the extraradical mycelia (ERM), Fe deficiency induced activation of a plasma membrane-localized ferric reductase, an enzyme that reduces Fe(III) sources to the more soluble Fe(II). Yeast mutant complementation assays showed that RiFRE1 encodes a functional ferric reductase and RiFTR1 an iron permease. In the heterologous system, RiFTR1 was expressed in the plasma membrane while RiFTR2 was expressed in the endomembranes. In the ERM, the highest expression levels of RiFTR1 were found in mycelia grown in media with 0.045 mM Fe, while RiFTR2 was upregulated under Fe-deficient conditions. RiFTR2 expression also increased in the intraradical mycelia (IRM) of maize plants grown without Fe. These data indicate that the Fe permease RiFTR1 plays a key role in Fe acquisition and that RiFTR2 is involved in Fe homeostasis under Fe-limiting conditions. RiFTR1 was highly expressed in the (IRM), which suggests that the maintenance of Fe homeostasis in the IRM might be essential for a successful symbiosis., This research was supported by the Ministerio de Economía, Industria y Competitividad (AGL2015-67098-R). Elisabeth Tamayo was supported by a PhD contract (JAEPre054) from CSIC.

The aim of this Chapter is to review and integrate current knowledge of the impact of mycorrhizal symbioses on plant functioning and adaptation with specific emphasis on P acquisition at various levels of cellular organization, from the molecular, biochemical and physiological to the whole plant. Accordingly, the available information will be structured as follows: (i) mycorrhizas as a plant strategy for P acquisition; (ii) fungal-plant integration to establish functional arbuscular mycorrhizal (AM) symbiosis; (iii) functional biology of Pi uptake by AM plants; (iv) ecological impact of AM symbiosis on plant community structure and productivity; and (v) mycorrhizosphere interactions and ecosystem P cycling.