Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy Introduction Phytohormones, as a signaling molecule, regulate endogenous plant growth, as well as infuence the metabolism and physiological processes of a plant [1]. Plants have adapted to biotic and abiotic stresses with the mediating role of phytohormone in the regulation of stress [2-4]. Phytohormones alter their levels upon the encounter with abiotic stress, such as heavy metal stress [1, 5]. Phytohormones are the vital components of complicated signaling networks in the current stress response models, which include salicylic acid (SA), ethylene (Et), abscisic acid (ABA) [6], and the new members jasmonic acid (JA), brassinosteroids (BRs), and strigolactones (SLs) [7]. Phytohormones are known as a regulator of plant growth and development and play an important role in response to abiotic and biotic stresses [8]. They are a small molecule with low concentration, but play an important role as a chemical messenger in the regulation of cells in plants [9]. There are two categories of phytohormones, which Pol. J. Environ. Stud. Vol. 29, No. 2 (2020), 1-12 Review The Role of New Members of Phytohormones in Plant Amelioration under Abiotic Stress with an Emphasis on Heavy Metals Abolghassem Emamverdian 1, 3 , Yulong Ding 1, 3 *, Yinfeng Xie 1, 2 1 Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China 2 College of Biology and the Environment, Nanjing Forestry University, Nanjing, China 3 Bamboo Research Institute, Nanjing Forestry University, Nanjing, China Received: 27 February 2019 Accepted: 22 April 2019 Abstract In addition to regulating plant growth and development, phytohormones play an essential role in the response to abiotic and biotic stress – especially heavy metal stress. In response to environmental stressors, phytohormones act as signaling molecules in both exogenous and endogenous signaling pathways. In parts of the rhizosphere, phytohormones have an exogenous role, and when regulating plant growth and development, they have an endogenous role. Phytohormones and their associated signaling pathway network are involved in plant responses to heavy metal stress. These molecules can improve the plant defense system by increasing antioxidant enzyme activity and degrading lipoperoxidation and H 2 O 2 . Phytohormones are divided into classical phytohormones such as auxins, ethylene, gibberellins, and cytokinins, that have been investigated for many years and the new members, such as jasmonates, brassinosteroids, and strigolactones, which have been little studied. In this review article, we investigated the main mechanisms involved in the amelioration of heavy metals by the three new phytohormones to provide more knowledge about their detoxifcation mechanisms. Keywords: abiotic stress, heavy metals, jasmonates, brassinosteroids, strigolactones *e-mail: ylding@vip.163.com DOI: 10.15244/pjoes/108687 ONLINE PUBLICATION DATE: