Phytohormones and their metabolic engineering for abiotic stress tolerance in crop plants

TLDR

Abiotic stresses such as drought, salinity, heat, cold, flooding, and UV radiation cause widespread crop losses, and their prevalence is expected to increase with climate change, making the identification of plant stress‑response mechanisms—particularly phytohormones like auxins, cytokinins, ethylene, gibberellins, brassinosteroids, jasmonates, and strigolactones—critical for developing tolerant crops. This review summarizes and critically evaluates the roles of phytohormones in plant growth, development, and abiotic stress tolerance, and examines their engineering for conferring tolerance in transgenic crops. The authors describe recent successes in elucidating phytohormone functions under stress conditions. The review concludes with an overview of recent progress, future prospects, and the limitations and challenges of phytohormone engineering for inducing abiotic stress tolerance in crops.

Abstract

Abiotic stresses including drought, salinity, heat, cold, flooding, and ultraviolet radiation causes crop losses worldwide. In recent times, preventing these crop losses and producing more food and feed to meet the demands of ever-increasing human populations have gained unprecedented importance. However, the proportion of agricultural lands facing multiple abiotic stresses is expected only to rise under a changing global climate fueled by anthropogenic activities. Identifying the mechanisms developed and deployed by plants to counteract abiotic stresses and maintain their growth and survival under harsh conditions thus holds great significance. Recent investigations have shown that phytohormones, including the classical auxins, cytokinins, ethylene, and gibberellins, and newer members including brassinosteroids, jasmonates, and strigolactones may prove to be important metabolic engineering targets for producing abiotic stress-tolerant crop plants. In this review, we summarize and critically assess the roles that phytohormones play in plant growth and development and abiotic stress tolerance, besides their engineering for conferring abiotic stress tolerance in transgenic crops. We also describe recent successes in identifying the roles of phytohormones under stressful conditions. We conclude by describing the recent progress and future prospects including limitations and challenges of phytohormone engineering for inducing abiotic stress tolerance in crop plants.