Microorganisms-Plant Interactions in Alpine ecosystem: a hotspot for studying the impact of climate change

Alpine regions exhibit significant environmental diversity, with strong altitudinal gradients and a wide range of climatic conditions within a relatively small spatial area, which makes them ideal hotspots for studying the impact of climate change on soil ecosystems. In particular, while it has been observed that plant cover is increasing at higher altitudes, its consequences on the diversity, abundance, and functionality of associated microbial communities remain uncertain. Prokaryotic and eukaryotic microorganisms living in these habitats play a crucial role in regulating soil health, nutrient cycling, and directly influencing plant growth, development, and resilience. Indeed, one of the most dramatic consequences of climate change is the alteration of the delicate balance between photosynthetic carbon assimilation and its subsequent release into the atmosphere, through respiration. Understanding the intricate ecological processes underlying the interactions between microbial communities and above-ground plant coverage requires an integrated multidisciplinary approach that brings together various fields of expertise. The MICROPLANTALP project, through a study that considers both soil microorganisms and plants, aims at gaining insights into ecological responses under possible global warming scenarios. This will be achieved through the comparison of two complementary transplantation approaches with the aim to characterize the responses of an alpine ecosystem (Mont Blanc area, Val Veny, Courmayeur). Soil monoliths, including native plants, collected at high altitudes (2500 m), are the model on which the study is focused. In the first approach, monoliths were transplanted to a lower latitude (1,000 meters elevation difference), while in the second experiment, other monoliths collected in the same area have been exposed to two different future climate change scenarios at the Montpellier Ecotron facility. Soil bacterial and fungal diversity of samples collected in their natural environment (control samples) and those from the two transplantation experiments will be characterized using a DNA metabarcoding approach (Illumina MiSeq). Additionally, the metabolic activity of microbial communities in soil samples will be evaluated through enzymatic activity assays targeting enzymes involved in C and N cycling. Moreover, the abundance of specific taxonomic groups of interest and of genes involved in the pathways mentioned above will be analysed through qPCR approaches. The data obtained will be compared and integrated with plant growth and carbon fluxes and several soil physicochemical parameters. By analyzing changes in the taxonomic structure and metabolic activities of microbial communities and foresee the plant-soil carbon fluxes under various climatic scenarios, models on how these ecosystems may evolve in the future will be developed. These predictive capabilities are vital for devising effective conservation and management strategies to safeguard these delicate ecosystems from the impacts of climate change.