Understanding the role of bacterial communities associated with the roots of Alnus acuminata: a pathway to improve restoration strategies of degraded lands in Ecuador

Nubia Guzmán ¹, Lara A. Quaglini ², Sarah Caronni ², Raffaella Ansaloni ³, Rodolfo Gentili ², Sandra Citterio ²

Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza Della Scienza 1, 20126 Milan, Italy; Azuay Herbarium (HA), University of Azuay, Cuenca, Ecuador ¹, Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza Della Scienza 1, 20126 Milan, Italy ², Azuay Herbarium (HA), University of Azuay, Cuenca, Ecuador ³

Land degradation is one of the most concerning issues facing the world today. It is defined as a set of human-induced processes leading to reduction or loss of biological or economic productivity, that result in decreased yields, incomes, food security, and in the loss of vital ecosystem services. Consequently, restoration has become a key strategy to combat land degradation and reverse biodiversity loss. A prerequisite for restoring degraded soils is the identification and proper implementation of suitable technologies. One strategy, to enhance the efficiency of these technologies is to explore plant-microbe interactions. Indeed, the plant symbiotic relationships with bacteria drive key ecosystem processes, lead to a number of benefits such as the promotion of plant growth and the mobilization of nutrients that are not readily available to plants, especially in degraded soils. Alnus acuminata, a native tree of the Ecuadorian Andes, shows great potential like specie to be investigated, due to its remarkable adaptability to various environmental conditions, rapid growth, and ability to colonize disturbed habitats, largely due to its strong association with microorganisms. The aim of this study is to determine the role of bacterial communities associated to the A. acuminata root system in promoting its growth, in order to discover new beneficial microorganisms to be used for an effective restoration of Ecuador degraded lands. Using next-generation sequencing of 16S ribosomal RNA gene amplicons, we investigated the bacterial communities in the bulk soil, rhizosphere and roots-nodules endosphere of A. acuminata growing in a native conserved forest and in a degraded area. The analysis showed that the total number of known bacterial genera in the bulk soil was 357, of which 13 were exclusive to the native forest and 42 to the degraded area. In the rhizosphere, 323 genera were identified, of which 47 were exclusive to the native forest and 19 to the degraded area. Regarding to roots (288 total genera) and nodules (233 total genera), more exclusive bacterial genera were identified in the degraded area, with 116 and 84 respectively, compared to 43 and 62 genera exclusive to the native forest. PCoA analysis revealed a marked difference in bacterial communities between the native forest and the degraded area in the soil-rhizosphere, while endophytic communities exhibited some variation but were not as clearly distinct. Interesting the bacteria community revealed a more abundance of Actinomycetota genera in the degraded areas across bulk soil, rhizosphere and nodule endosphere. It includes strains capable of decomposing recalcitrant organic matter and producing metabolites that promote plant establishment and growth. Additionally, the common presence of the genera Paraburkholderia, Bradyrhizobium and Pseudomonas in the root-nodule endosphere highlights interesting strains for developing microbial consortia for the restoration of degraded high-mountain lands in Ecuador.

Main author career stage: Master student

Contribution type: Poster

First choice session: 2. Ecology

Second choice session: 3. Biodiversity and global change