Phytohormone Priming: Regulator for Heavy Metal Stress in Plants

Abstract

Phytohormones act as chemical messengers and, under a complex regulation, allow plants to sustain biotic and abiotic stresses. Thus, phytohormones are known for their regulatory role in plant growth and development. Heavy metals (HMs) play an important role in metabolism and have roles in plant growth and development as micronutrients. However, at a level above threshold, these HMs act as contaminants and pose a worldwide environmental threat. Thus, finding eco-friendly and economical deliverables to tackle this problem is a priority. In addition to physicochemical methods, exogenous application of phytohormones, i.e., auxins, cytokinins, and gibberellins, can positively influence the regulation of the ascorbate-glutathione cycle, transpiration rate, cell division, and the activities of nitrogen metabolism and assimilation, which improve plant growth activity. Brassinosteroids, ethylene and salicylic acid have been reported to enhance the level of the anti-oxidant system, decrease levels of ROS, lipid peroxidation and improve photosynthesis in plants, when applied exogenously under a HM effect. There is a crosstalk between phytohormones which is activated upon exogenous application. Research suggests that plants are primed by phytohormones for stress tolerance. Chemical priming has provided good results in plant physiology and stress adaptation, and phytohormone priming is underway. We have reviewed promising phytohormones, which can potentially confer enhanced tolerance when used exogenously. Exogenous application of phytohormones may increase plant performance under HM stress and can be used for agro-ecological benefits under environmental conditions with high HMs level.

Hydrogen sulfide alleviates chromium stress on cauliflower by restricting its uptake and enhancing antioxidative system

“…Agricultural crops are under severe threats of various biotic and abiotic stresses, including salinity, drought and trace element stress (Adrees et al , Khan et al , Hussain et al , , b, Sytar et al ). Trace element stress is the most prevalent of these stresses, which not only inhibits crop growth by polluting agriculture soils, but also cause diseases in humans and animals (Hu et al , Song et al , Liu et al , Kataria et al ).…”

Long-Term Effect of Heavy Metal–Polluted Wastewater Irrigation on Physiological and Ecological Parameters of Salicornia europaea L.

“…Higher ethylene production is due to the peaked expression of ethylene-responsive genes (Sharma et al 2020). Higher production of reactive oxygen species (ROS), induced by some heavy metals, causes oxidative stress (Mittler 2002;Sytar et al 2018). Heavy metals lead to damaging effects such as photochemical reactions, chlorophyll degradation, enzyme inhibition, disruption of membranes integrity, and reduction in metabolic efficiency and carbon fixation (Liu et al 2005;Seregin and Ivanov 2001).…”

Salicylic acid and potassium nitrate promote flowering through modulating the hormonal levels and protein pattern of date palm Phoenix dactylifera ‘Sayer’ offshoot

“…2 C, D). Salicylic acid rose IAA, CK and ABA levels, enhanced cell division in the apical meristem, and improved flowering of the plant (Sytar et al, 2019). In contrast, Alonso-Ramírez et al (2009) reported that there was a cross-talk between SA and GA3 in Arabidopsis thaliana during abiotic stress conditions.…”