Changes in Soil Microbiome Mediated by Root Volatiles Enhanced Manganese Tolerance of an Invasive Plant Species

Many invasive plants exhibit high heavy metal tolerance, but the roles of root-associated soil microbiomes in this process remain poorly understood. Heavy metal stress can alter the release of plant volatile organic compounds (VOCs), potentially influencing plant-soil feedbacks. This study utilised an aggressive invasive plant species Phytolacca americana as a study model, to assess the effects of different levels of soil manganese (Mn) stress on the emissions of root VOCs, and their subsequent influence on soil microbial communities. Results obtained here indicated that elevated Mn stress levels notably increased the quantity and altered the composition of root VOCs, subsequently influencing the diversity and composition of soil microbiomes. Specifically, a decrease in bacterial diversity and an increase in beneficial bacterial genera were observed. Limonene was identified as a key VOC compound influencing bacterial community composition, potentially promoting the accumulation of beneficial bacterial taxa such as Bacillus in soil. Reintroduction of inoculated soil collected from Mn-stressed plants significantly enhanced the tolerance of P. americana to Mn treatment. Elemental analysis suggested that the improved plant tolerance to Mn following soil reintroduction may be attributed to enhanced nutrient uptake that may be facilitated by beneficial microorganisms rather than reduced Mn accumulation in plant tissues.