title: Ethylene Improves Root System Development under Cadmium Stress by Modulating Superoxide Anion Concentration inArabidopsis thaliana.
abstract: This work aims at identifying the effects of ethylene on the response ofArabidopsis thalianaroot system to cadmium chloride (CdCl2) stress. Two ethylene-insensitive mutants,ein2-5andein3-1eil1-1, were subjected to (25, 50, 75, and 100 μM) CdCl2concentrations, from which 75 μM concentration decreased root growth by 40% compared with wild type Col-0 as a control. Ethylene biosynthesis increased in response to CdCl2treatment. The length of primary root and root tip inein2-5andein3-1eil1-1decreased compared with wild type after CdCl2treatment, suggesting that ethylene play a role in root system response to Cd stress. The superoxide concentration in roots ofein2-5andein3-1eil1-1was greater than in wild type seedlings under Cd stress. Application of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) (a precursor of ethylene biosynthesis) in different concentrations (0.01, 0.05 and 0.5 μM) decreased superoxide accumulation in Col-0 root tips and increased the activities of superoxide dismutase (SOD) isoenzymes under Cd stress. This result was reversed with 5 μM of aminoisobutyric acid AIB (an inhibitor of ethylene biosynthesis). Moreover, it was accompanied by increase in lateral roots number and root hairs length, indicating the essential role of ethylene in modulating root system development by controlling superoxide accumulation through SOD isoenzymes activities. The suppressed Cd-induced superoxide accumulation in wild type plants decreased the occurrence of cells death while programmed cell death (PCD) was initiated in the root tip zone, altering root morphogenesis (decreased primary root length, more lateral roots and root hairs) to minimize the damage caused by Cd stress, whereas this response was absent in theein2-5andein3-1eil1-1seedlings. Hence, ethylene has a role in modulating root morphogenesis during CdCl2stress inA. thalianaby increasing the activity of SOD isoenzymes to control superoxide accumulation.
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry UniversityHarbin, China; Botany Department, Faculty of Science, Menoufia UniversityShibin El Kom, Egypt.
authors.forename: Ann
authors.initials: A
authors.lastname: Abozeid
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry UniversityHarbin, China; The College of Landscape, Northeast Forestry UniversityHarbin, China.
authors.forename: Zuojia
authors.initials: Z
authors.lastname: Ying
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry UniversityHarbin, China; Guizhou Academy of Tobacco ResearchGuiyang, China.
authors.forename: Yingchao
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry University Harbin, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry University Harbin, China.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry University Harbin, China.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Tang
keywords: Arabidopsis thaliana; Cd stress; ethylene; programmed cell death; root system; superoxide