IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Rhizospheric Penicillium community in Austrocedrus chilensis changes with health condition: ecological discussion and opportunity to find biocontrol agents
Autor/es:
S.M. ROMERO; M. L. VELEZ; J. A. MARFETAN
Lugar:
Santiago
Reunión:
Congreso; 1. X Congreso Latinoamericano de Micología; 2020
Institución organizadora:
Asociación Latino Americana de Micología
Resumen:
Austrocedrus chilensis (Ciprés de la cordillera) is an endemic Cupressaceae species distributed in southern Argentina and Chile. This tree species is an essential component of the Patagonian native forest but also have an important impact in local economy due to the reduction of the volume of extraction of high quality wood. Throughout its distribution area, A. chilensis suffers a mortality commonly known as ??mal del ciprés?? or ??Austrocedrus root disease (ARD)?? or caused by Phytophthora austrocedri. Because of the severity of the disease, A. chilensis has been declared as a ?near threatened? species. Although Phytophthora diseases can be chemically managed, fungicides are unaffordable to be used in big natural areas and also may have a negative impact on the ecosystem, especially in soil microorganisms communities. In this sense, biocontrol strategies are a useful alternative to control Phytophthora diseases. One of the difficulties in developing biocontrol strategies is the lack of information about the rhizospheric microbiota and its possible role in controlling ARD. For this reason, the aim of this study was to describe rhizospheric Penicillium diversity associated with living trees of A. chilensis forests, comparing Penicillium diversity between healthy sites and sites with high incidence of ARD. Samples were taken from three sites in Los Alerces National Park, Argentina. Two of these sampling sites showed high prevalence of ARD, with several affected trees. In the third site, asymptomatic trees were collected. Plants were carefully extracted (n=6), and most of soil was removed in order to obtain only the roots together with the thin layer of soil in direct contact with them (rhizospheric soil). Roots and rhizospheric soil were submerged 15 min in 250 ml of sterile water. 1/10, 1/100 and 1/1000 dilutions were made from original suspensions. These dilutions were plated in potato dextrose agar with chloramphenicol (PDAc) and Rose Bengal Agar (RBA) Petri dishes were incubated 7 days. Isolates were identified using morphological and molecularly (Beta-tubulin gene region) techniques. During the survey, 66 Penicillium spp. isolates were obtained from rhizospheric soil. These isolates were separated in 27 different morphospecies. Morphospecies were defined based on the morphology of each isolate. These isolates were included in seven Penicillium sections (Aspergilloides, Brevicompacta, Canescentia, Citrina, Exilicaulis, Fasciculata and Ramosa sections) and 11 Penicillium species (P. glabrum, P. bussumense, P. fuscum, P. bialowiezense, P. arizonense, P. palitans, P. expansum, P. manginni, P. swiecickii and P. lanosum), and 14 unidentified species.In addition, it was evaluated whether community composition could be involved in the protection of healthy seedlings in sites with ARD, by using multivariate analysis. We first compared the fungal communities present in the rhizosphere of A. chilensis to find possible Penicillium species aggrupation in relation with different sites and conditions, by running a Two Way Cluster Analysis. Differences in communities? composition were evaluated among different sites with different health status. Afterwards, we further described how groups of rhizospheric Penicillium were related with sites and health status using Correspondence Analysis calculated for presence?absence data of fungal species. Two Way Cluster analysis relating Penicillium species with different sites and health conditions showed that the distribution of the Penicillium species not only changed between health conditions but also between sites in the same condition. Two Way Cluster analysis showed 5 clusters, separating species present in all sites, species only found in sites without ARD and Penicillium species found in only one of the sites with disease incidence. An additional group was composed of species shared only by sites with ARD. Correspondence analysis confirmed the groups formed by cluster analysis with sites and health status. In vitro biocontrol assays showed that several Penicillium isolates have a negative impact on P. austrocedri growth and survival, specially species shared by healthy trees in sites with and without ARD. Evidence suggests that Penicillium isolates can be evaluated for utilization in biocontrol strategies.