Altitude-dependent influence of Artemisia brevifolia on its rhizosphere microbiome in Ladakh region of the Western Himalayas

Abstract

Altitude-induced variations significantly influence plant physiology, shaping the diversity and composition of prokaryotic and fungal communities in the rhizosphere soil. This study investigates the impact of altitude on the rhizosphere microbiome of Artemisia brevifolia in the Ladakh region of the Western Himalayas. Alpha diversity indices reveal a decline in both prokaryotic and fungal diversity in rhizosphere soil compared to bulk soil, with a more pronounced effect on prokaryotic communities at different altitudes. Altitude variation significantly impacts prokaryotic and fungal beta-diversity, leading to distinct microbial communities at different elevations. Notably, the rhizosphere communities at higher altitudes exhibit little overlap with bulk soil communities, indicating a unique microbial assemblage possibly in response to harsh environmental conditions. The dominant prokaryotic phyla include Actinobacteriota, Proteobacteria, Chloroflexi, and Acidobacteriota, while the fungal communities are dominated by Ascomycota and Basidiomycota. A significantly higher frequency of rhizobia was noted in the A. brevifolia rhizosphere at both locations, with the genus Rhizobium prevalent at lower altitudes and Mesorhizobium at the higher altitudes. Predicted functions of prokaryotic communities revealed a higher abundance of pathways associated with the biosynthesis of siderophores, secondary metabolites and aromatic-compounds, and denitrification in the rhizosphere. Additionally, a higher abundance of gene clusters associated with nitrogen fixation and phosphorus metabolisms was noted in rhizosphere particularly at higher elevations.In summary, this comprehensive study highlights the unique structure and function of microbial communities along increasing elevations, particularly in the rhizosphere, potentially aiding the host plant in thriving under the stressful conditions of high altitudes in the climate-sensitive Himalayas.