Plant Bioregulators for Sustainable Agriculture: Integrating Redox Signaling as a Possible Unifying Mechanism

Abstract Increasing agricultural productivity and sustainability will have to be prioritized to enhance food production. The major challenge toward this emanates from multiple stress factors and unpredictable climatic conditions. Thus, it is critical to understand and characterize the plant responses to changing environmental conditions. Needless to say, plant breeding has contributed a great deal to crop improvement over the past decades and is still supplementing the biotechnological advancement to bring technologies for enhancing crop yield. In recent years, although several stress tolerant transgenic lines have been developed; however, their performance in farmer's field is still to be tested. In this regard, present review describes Low External Input and Sustainable Agriculture (LEISA) based agriculture wherein low concentration of plant bioregulators (PBRs) are applied externally at a suitable developmental stage to boost the plant signaling which finally leads to enhanced growth and crop yield. There is a wide range of chemical- and hormone-based PBRs used for different crops and here in, we have proposed a unified mechanism for their mode of action. This is based upon PBR's ability to fine tune plant redox homeostasis which regulates root growth for improving plant water/nutrient status, photosynthetic efficiency and source–sink homeostasis for enhanced crop yield and metabolism for overall improvement in plant growth. The knowledge gaps and quality control aspect have also been discussed to ensure the adoptability and applicability of PBRs on a wider scale.