Molecular Microbiology Research 2024, Vol.14, No.5, 236-247 http://microbescipublisher.com/index.php/mmr 239 In summary, rice roots exhibit a range of morphological, physiological, and genetic adaptations to cope with abiotic stresses. These adaptations are further enhanced by the presence of beneficial microbes in the rhizosphere, which play a synergistic role in improving the plant's stress tolerance. Understanding these complex interactions between roots and rhizosphere microbes is crucial for developing strategies to enhance rice productivity under adverse environmental conditions. 3 Rhizosphere Microbial Communities 3.1 Composition and diversity of rhizosphere microbes The rhizosphere is the soil region immediately surrounding plant roots, which hosts a diverse array of microbial communities that play crucial roles in plant health and stress tolerance (Figure 2) (Ding et al., 2019). Rhizosphere microorganisms are mainly composed of bacteria, actinomycetes, fungi, algae, protozoa and viruses, and bacteria can account for 90% of the total number of microorganisms, which is the largest group in the composition of soil microorganisms. Figure 2 Schematic of a rice root section presenting the structure of the rhizosphere, rhizoplane and endosphere in a flooded paddy soil. The rhizosphere is a small soil compartment that is around the rice roots and is affected by the rice roots. In flooded paddy soils, O2 is secreted through the aerenchyma of rice roots leading to oxic zones around the roots (e.g. the rhizosphere) which are surrounded by the anoxic bulk soil. The rhizoplane is the surface of the rice roots (including root hairs). The endosphere is a compartment inside the rice roots (Adopted from Ding et al., 2019). Studies have shown that the composition and diversity of these microbial communities can vary significantly depending on several factors, including plant genotype, soil type, and environmental conditions (Hu et al., 2020; Lazcano et al., 2021). For instance, research has demonstrated that drought stress leads to a significant restructuring of the rice root-associated microbiomes, with notable changes in the bacterial and fungal
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