Chapter 24 - Rooting for resilience: Harnessing the rhizomicrobiome for abiotic stress survival in plants

Abstract

The rhizomicrobiome, a diverse community of microorganisms around plant roots, influences plant growth and development by performing various functions, including nitrogen fixation, phytohormone synthesis, nutrient availability, and biocontrol of phytopathogens in natural or stressful conditions. It enhances plant adaptability to abiotic stress, known as Induced Systemic Tolerance (IST), protecting them from salinity, drought, temperature, osmotic stress, and heavy metal exposure. Rhizobacteria play a crucial role in affecting a plant's nutrient status, growth, development, health, and salt levels through processes like ethylene synthesis/breakdown, EPS secretion, osmoprotectants, jasmonic acid (JA), gibberellins (GAs) and salicylic acid (SA), as well as controlling various physiological processes in the plant, such as root initiation, elongation, and root hair development. Exo-poly saccharides (EPS) secreted by bacteria shield it from water scarcity by controlling the diffusion of organic carbon sources and improving water retention. In saline environments, EPS is also help to plants as it binds to cations like Na+ and make it inaccessible to plants. Peroxidase, catalase and superoxide dismutase were accumulated in plant by stimulation of rhizobacteria also improved the plant's ability to withstand oxidative stress. The essential players in the IST against drought and salt stress are bacteria that generate 1- aminocyclo-propane 1-carboxylate deaminase (ACC). Bacterial ACC deaminase converts the ethylene precursor ACC into 2-oxobutyrate and ammonia, reducing the concentration of ethylene in plant roots and relieving the inhibition of the production of auxin response factors, which indirectly promotes plant growth. In this chapter, we address the significant challenge posed by abiotic stress to crop production. We explore the potential of the rhizomicrobiome in bolstering soil fertility and promoting plant growth, particularly in the face of abiotic stressors such as salinity and drought. This approach aims to foster sustainable practices for crop production and protection.