Open Access

ARTICLE

Effects of Melatonin on Growth, Physiology and Gene Expression in Rice Seedlings Under Cadmium Stress

Xiachen Lv^1,#, Yunxia Fang^1,#, Lantian Zhang¹, Weiyi Zhang¹, Ling Xu¹, Jingjin Han¹, Bailing Jin², Xian Zhang¹, Xiaoqin Zhang^1,*, Dawei Xue^1,*

1 College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 310036, China.
2 Hangzhou Foreign Languages School, Hangzhou, 310023, China.
# These authors contributed equally to this work.
* Correspondence Authors: Xiaoqin Zhang. Email: xiaoqinzhang@163.com; Dawei Xue. Email: dwxue@hznu.edu.cn.

Phyton-International Journal of Experimental Botany 2019, 88(2), 91-100. https://doi.org/10.32604/phyton.2019.06622

Abstract

Melatonin (MLT) is a hormonal substance found in many organisms and can improve plant stress resistance. In this study, the japonica rice variety Y32 and indica rice variety NJ6 were cultivated in hydroponics under different concentrations of CdCl₂ at the two-leaf stage. The growth, physiological and biochemical responses of the seedlings and the expression of cadmium (Cd)-related genes under exogenous melatonin (MLT) treatment were assessed. The results indicated that Cd stress destroyed the dynamic balance between reactive oxygen species (ROS) production and removal, resulting in ROS accumulation, membrane lipid peroxidation, and impaired growth and development. Following the application of exogenous MLT to rice seedlings, increases in plant biomass including both underground and above-ground areas were observed. MLT also scavenged the inhibition of superoxide dismutase (SOD) and peroxidase (POD) in a concentration dependent manner in response to Cd stress. Catalase (CAT) activity and malondialdehyde (MDA) expression also decreased following MLT treatment. Amongst the six Cd-related genes assessed, five genes were down-regulated and one was up-regulated in response to MLT treatment. Taken together, these data demonstrate that MLT improves the resilience of rice seedlings at the biochemical, physiological, and molecular levels, and diminishes the damage caused by Cd stress.

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