Plant Growth-Regulating Substances in the Rhizosphere

Abstract

Plant-microbe interactions play a pivotal role in shaping the soil ecosystem and influencing plant growth and development. Soil microorganisms are key players in synthesizing biologically active substances, including phytohormones, which directly or indirectly influence plant physiology. This chapter explores the production of phytohormones by soil microorganisms and their effects on plant growth and development. Microbial communities in the rhizosphere produce a diverse array of metabolites that impact plant growth by directly affecting plant physiology or modifying the soil environment. Phytohormones, such as auxins, cytokinins, gibberellins, ethylene, and abscisic acid, are among the biologically active substances produced by soil microorganisms. These substances have significant ecological effectiveness on living organisms, influencing plant growth and health. The chapter discusses the biosynthesis and metabolism of phytohormones by soil microorganisms, Similarly, cytokinins are produced by diverse genera of rhizosphere and epiphytic bacteria, affecting plant growth, stress tolerance, and disease resistance. The ecological significance of phytohormones in the soil, particularly their impact on plant growth and development, is highlighted. For instance, ethylene, produced by soil microorganisms and plant roots, influences various aspects of plant growth, while abscisic acid plays a critical role in stress responses and plant development. In conclusion, Improving agricultural yield and sustainability requires an understanding of how soil microorganisms produce and use phytohormones. Prospective research encompasses clarifying the mode of action of microbial phytohormones, assessing precursor-inoculum interactions, and investigating phytohormone interactions within the rhizosphere. With this knowledge, agricultural solutions to encourage plant development and mitigate environmental stress can be developed.