Interactions between plant hormones and heavy metals responses

Abstract

Heavy metals are natural non-biodegradable constituents of the Earth's crust that accumulate and persist indefinitely in the ecosystem as a result of human activities. Since the industrial revolution, the concentration of cadmium, arsenic, lead, mercury and zinc, amongst others, have increasingly contaminated soil and water resources, leading to significant yield losses in plants. These issues have become an important concern of scientific interest. Understanding the molecular and physiological responses of plants to heavy metal stress is critical in order to maximize their productivity. Recent research has extended our view of how plant hormones can regulate and integrate growth responses to various environmental cues in order to sustain life. In the present review we discuss current knowledge about the role of the plant growth hormones abscisic acid, auxin, brassinosteroid and ethylene in signaling pathways, defense mechanisms and alleviation of heavy metal toxicity.

Hormesis in Plants: The Role of Oxidative Stress, Auxins and Photosynthesis in Corn Treated with Cd or Pb

“…We would like to stress that an increase in the IAA and flavonol content have been proposed as the key factors in hormesis here for the first time. In general, the literature on metals and hormesis is dominated by studies on the role of oxidative stress and phytohormones such as abscisic acid, ethylene or jasmonates, with little information on the role of IAA and flavonols [3,4,6,41,54]. The results presented here also suggest that an increase in the photosynthesis and transpiration rates are not necessary for stimulating hormetic growth.…”

“…Phytohormones such as auxins have been found to play an important role in plant tolerance and the alleviation of the stress that is induced by HMs [54]. It has been suggested that the cellular level of auxins increases under a low level of abiotic stress, which stimulates vegetative growth, thus leading to the hormetic effect [3,55].…”

“…Although Elobeid and Polle ([33] and literature therein) reported that a high concentration of Cd in Glycine max inhibited auxin biosynthesis and reduced growth, whereas exposure to a low concentration of Cd stimulated auxin biosynthesis. Other studies have shown that the application of exogenous auxin improves a plant's protection against HM toxicity and can reverse the growth inhibition that is caused by heavy metals [54]. Liphadzi et al [56] documented that the addition of exogenous IAA caused a significant increase in the biomass of the roots and stems of Helianthus annuus plants grown in soil that had been moderately contaminated with Pb compared to the untreated plants.…”

Potential of hydrogen (pH) differentially modulates cadmium stress response in abscisic acid-deficient sitiens tomato mutant

“…ABA signaling has been considered as an important factor in Cd-signal transduction. A rapidly increase on ABA's level under stressful conditions triggers response mechanisms via several ABA-responsive genes, ultimately leading to physiological changes such as the rapid closing of stomata (Asgher et al 2015;Bücker-Neto et al 2017).…”

Effect of exogenous abscisic acid on morphological characteristics of winter wheat and spelt under hyperthermia

“…В умовах стресу концентрація гормону стрімко зростає, що дає змогу рослині адаптуватися та вижити [18]. Накопичення ендогенної АБК і подальше гальмування росту розглядають як адаптивну реакцію, спрямовану на збереження життєздатності рослини в несприятливих умовах і подальше відновлення після припинення стресового впливу [7]. АБК відіграє головну роль у регулюванні вмісту води контролем продихової провідності, а індуковане гормоном закриття продихів відбувається впродовж кількох секунд або хвилин від початку дії стресора [13].…”