Augmenting abiotic stress tolerance and root architecture: The function of phytohormone-producing PGPR and their interaction with nanoparticles

Root architecture has a key role in influencing plant growth and yield. In recent years, the agriculture sector has gained interest in harnessing the potential of plant growth-promoting rhizobacteria (PGPR) that possess the competence to produce phytohormones, with the aim of enhancing these desirable traits. Phytohormone-producing PGPR exert their influence on root development through the modulation of phytohormone production and distribution, encompassing auxins, cytokinins, and gibberellins. These beneficial bacteria stimulate lateral root proliferation, elongate root hairs, and promote the accumulation of root biomass, ultimately leading to heightened nutrient uptake and enhanced water absorption. Moreover, the phytohormones synthesized by PGPR serve to activate stress signalling pathways, thereby strengthening plant resilience against an abiotic stressor, viz., drought, heavy metal, salinity, and toxicity.This comprehensive review article highlights the role of these PGPR and their significant impact on augmenting root architecture in plants. The development of roots is often vulnerable to several abiotic factors, which in turn adversely affects the initial growth and overall health of the plants. This review thoroughly explores the complex interaction of phytohormones in mitigating abiotic stresses through their modulation of root development. Additionally, the interaction between phytohormone-producing PGPR and nanoparticles (NPs) has emerged as a significantly promising approach to reinforce plant growth and an ability to improve the colonization and activity of PGPR in the rhizosphere, further expanding their beneficial effects on root architecture and stress tolerance. Within this context, we have discussed the stimulating dynamics of PGPR interaction with NPs in sustaining root architecture to optimize plant health and effectively mitigate abiotic stresses.