ABSTRACT
More than 50% of the global population consume rice as their staple food. Thus, to meet the global food security, a significant rice production is required to feed the growing population. Conversely, rice cultivation significantly emits greenhouse gas in the atmosphere. Thus, in recent years, researchers have emphasized the plant root system-associated microbes, and those inhabit the root as microbial community (microbiome), to address this situation. Microbes colonizing the various compartments of the root system such as endosphere, rhizoplane, and rhizosphere are thought to play an important role in improving crop health and sustainable rice production by alleviating greenhouse gas emissions. Intensive water management and root radial oxygen loss (ROL) by rice root create a redox gradient around the root that leads from root surface to bulk soil, making the root system a unique microbial niche. This enabled dynamic biogeochemical cycles of elements leading to strong couplings of microbial functional processes. Root exudates of plant metabolite attract the microbe to colonize the root system, whereas plants depend upon beneficial interactions between roots and microbes for nutrient availability, growth promotion, and disease suppression. Although the high-throughput DNA sequencing and the –“omics” technologies considerably enlighten the animal microbiomes, our current understanding on plant microbiome is still limited. This chapter summarizes the current understanding of microbial communities and their function inhabiting the various compartments associated with rice root. Key factors shaping the root-associated microbiomes, biogeochemical cycling of some elements therein, and their coupling mechanisms are also described. Community dynamics and resilience of the root-associated microbiome under adverse situation have also been elucidated.
