REVIEW PAPER
Mechanisms of Selected Plant Hormones
under Heavy Metal Stress
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1
Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China
2
Bamboo Research Institute, Nanjing Forestry University, Nanjing, 210037, China
3
Department of Agronomy and Plant Breeding, Faculty of Agriculture, Islamic Azad University,
Mashhad Branch, Mashhad 9187147578, Iran
Submission date: 2020-04-04
Final revision date: 2020-05-24
Acceptance date: 2020-05-25
Online publication date: 2020-09-07
Publication date: 2020-11-10
Corresponding author
Yulong Ding
Bamboo Research Institute, Nanjing Forestry University, longpan Rd. 159, 210037, nanjing, China
Pol. J. Environ. Stud. 2021;30(1):497-507
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ABSTRACT
The present review focuses on the role of auxin (IAA), cytokinins (CKs), ethylene (ET) and
abscisic acid (ABA) under heavy metal stress. From the onset of heavy metal stress in plants, cellular
levels of ABA tend to increase, leading to the establishment of signal communication and encoding
of genes associated with the enzymes involved in antioxidant stress responses. The mechanisms
of IAA phytohormones in terms of enhancing plant tolerance to stress mainly comprise developing
a link between hydrogen peroxide (H2O2) and auxin homeostasis, which can result in forming
a signaling interaction between them. The primary anti-phytotoxicity mechanism of ET in response
to heavy metal stress is related to modulating the interaction of ethylene with reactive oxygen
species (ROS) signaling, which is reflected in a synergy between induction of ROS and synthesis of
1-aminocyclopropane-1-carboxylic acid (ACC). CKs, particularly when applied exogenously, make a
positive contribution to alleviating stress emanating from plant metal exposure. This is achieved by
a reduction in ROS levels inside plant cells. Generally, CKs can ameliorate heavy metal stresses via
a three-way interaction involving exogenous CK, CK metabolism, and CK signaling. Our aims in this
work were to review the major hormonal responses of plants elicited by heavy metal stress.