Role of Phytohormones in Developing Heavy Metal Stress Resilience in Rice: Physiological–Molecular Adjustments, Crosstalk, and Prospects
摘要
Heavy metal-mediated (HM) damage to plants is a global concern which threatens food security. Despite efforts to guard plants from HMs, some areas of study into these toxic compounds have not been addressed. Fascinatingly, external supplementation of phytohormones has seen an impressive upturn in recent years. It has been well documented that auxin (IAA), cytokinin (CK), ethylene (ET), gibberellin (GA), and abscisic acid (ABA) are the traditional phytohormones; brassinosteroids (BRs), jasmonates (JA), and strigolactones (SLs) are the emergent classes of phytohormones. These small mediators can regulate HMs stress tolerance in plants, coordinating growth and differentiation via stress-responsive regulating cascade. Both external applications and alteration of natural phytohormone levels act as a defensive shield against HMs-induced toxicity. These phytohormones intensify HMs stress tolerance through various morphophysiological processes including improved root system, photosynthetic efficiency, nutrient uptake, antioxidant capacity, cell wall synthesis while reducing oxidative damage, and HMs uptake. In this review, authors have concentrated on the phytohormone-mediated strategies alongside hormonal interplay in countering noxious effects of HMs in rice. In addition, phytohormone-regulated genes preventing HMs toxicity in rice plants are also discussed. This update will provide an in-depth comprehension of how phytohormones influence HMs stress tolerance in rice and could navigate in developing strategies for enhancing plants’ tolerance potential against HMs in future. In summary, we infer that exogenous phytohormones treatment and genetic engineering of phytohormones-associated genes would be a promising tolerance strategy against HMs stress in crop plants.