Every organism on the earth maintains some kind of interaction with its neighbours. As plants are sessile, they sense the varied above-ground and below-ground environmental stimuli and decipher these dialogues to the below-ground microbes and neighbouring plants via root exudates as chemical signals resulting in the modulation of the rhizospheric microbial community. The composition of root exudates depends upon the host genotype, environmental cues, and interaction of plants with other biotic factors. Crosstalk of plants with biotic agents such as herbivores, microbes, and neighbouring plants can change host plant root exudate composition, which may permit either positive or negative interactions to generate a battlefield in the rhizosphere. Compatible microbes utilize the plant carbon sources as their organic nutrients and show robust co-evolutionary changes in changing circumstances. In this review, we have mainly focused on the different biotic factors responsible for the synthesis of alternative root exudate composition leading to the modulation of rhizosphere microbiota. Understanding the stress-induced root exudate composition and resulting change in microbial community can help us to devise strategies in engineering plant microbiomes to enhance plant adaptive capabilities in a stressful environment.

Global food requirements necessitating enhanced crop productivity have negative consequences such as soil degradation due to acidification and nutrient leaching escalated by excessive application of chemical fertilizers and consequently increasing greenhouse gas emission. This has sought sustainable organic approaches like soil amendment with biochar to mitigate the adverse consequences of these effects, ensuring balanced ecosystem functioning. Reconciling various studies, this review provides a better understanding of the belowground mechanisms decoding multifaceted traits associated with plant and biochar-microbe-soil tripartite interaction, including microbe-mediated regulation of C and N stoichiometry, soil enzyme functioning, regulation of greenhouse gases, soil respiration rate and alteration in abundance of microbial functional genes. Furthermore, this review exclusively gives holistic insights into specific microbes induced by biochar treatment and their role in altering soil C and N dynamics. It attempts to spur in-depth, long-term studies tackling challenges in sustainable agriculture and mitigate environmental issues to achieve C neutrality and N retention, envisaging a healthy soil ecosystem. Graphical Abstract