MicroPIXE technique to understand the distribution of copper during arbuscular mycorrhizal symbiosis

COLOMBO, ROXANA; BENAVIDEZ, MATÍAS; DEBRAY, ME; SCORZA, MARÍA VICTORIA; SILVANI, VANESA ANALÍA; GODEAS, ALICIA MARGARITA; STATELLO, MARINA; DE LA FOURNIERE, EMMANUEL; SCOTTI, ADALGISA

San Carlos de Bariloche

Simposio; II International Symposium of Mycorrhizal Symbiosis in South America; 2019

Soil tends to strongly retain heavy metals (HM) in their colloids and accumulate them. Edaphic contamination by HM compounds not only implies a detriment on the provided ecosystem services but also a risk for the environment and the health of living beings. The most common soil decontamination techniques involve high costs and environmental alterations. In this context, bioremediation methods are most appropriate as they stimulate the processes that naturally occur in soil. Among them, phytoremediation is a sustainable alternative. The vast majority of plant species are able to associate with arbuscular mycorrhizal fungi (AMF). This association plays a key role in the maintenance of functionality and diversity of ecosystems, and it also improves the survival and tolerance of plants to adverse conditions, enhances edaphic structure and increase the volume of explored soil, through the formation of hyphal networks. For this, it is considered that the AMF increase the efficiency of the bioremediation processes by adsorbing or absorbing the HM through the hyphal network or translocating it towards the host plant. The microPIXE technique allows to know the HM accumulation and distribution patterns in plants and microorganisms, being a valuable tool in studying where HM accumulate during the arbuscular mycorrhizal symbiosis. This work aims to use this technique to quantify and to map the location of copper (Cu), a very common toxic element, by using the in vitro culture system of transformed carrot roots associated to the AM fungal strain GC3 (Banco de Glomeromycota in vitro- BGIV). In order to understand the role of AMF in the rhizosphere of plants growing in soils with high content of Cu. In vitro experiments were performed in divided petri plates containing transformed carrot roots colonized by GC3 at one side (root compartment: RC), and sterile soil, artificially contaminated, or not, with 300 ppm of Cu (treatments: Cu+ and Cu-) at the other side, where only hyphae could access (hyphal compartment: HC). After three months, root, mycelia, spores and intraradical vesicules from the RC and HC were sampled at both treatments. Different accumulation patterns were observed between treatments. Cu was only detected in vesicules and roots of Cu+ treatment. P, Zn, Mn and Ca were strongly associated to every AMF structures. These results show an accumulation of HM in the fungal intraradical tissue during the symbiotic association and not in the plant itself