Abozeid Ann, Ying Zuojia, Lin Yingchao, Liu Jia, Zhang Zhonghua, Tang Zhonghua
Key Laboratory of Plant Ecology, Northeast Forestry UniversityHarbin, China; Botany Department, Faculty of Science, Menoufia UniversityShibin El Kom, Egypt.
Key Laboratory of Plant Ecology, Northeast Forestry UniversityHarbin, China; The College of Landscape, Northeast Forestry UniversityHarbin, China.
Front Plant Sci. 2017 Feb 24;8:253. doi: 10.3389/fpls.2017.00253. eCollection 2017.
This work aims at identifying the effects of ethylene on the response of root system to cadmium chloride (CdCl) stress. Two ethylene-insensitive mutants, and , were subjected to (25, 50, 75, and 100 μM) CdCl concentrations, 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 CdCl treatment. The length of primary root and root tip in and decreased compared with wild type after CdCl treatment, suggesting that ethylene play a role in root system response to Cd stress. The superoxide concentration in roots of and was 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 the and seedlings. Hence, ethylene has a role in modulating root morphogenesis during CdCl stress in by increasing the activity of SOD isoenzymes to control superoxide accumulation.
这项工作旨在确定乙烯对根系对氯化镉（CdCl）胁迫反应的影响。将两个乙烯不敏感突变体和暴露于（25、50、75和100μM）的CdCl浓度下，其中75μM浓度与作为对照的野生型Col-0相比使根生长降低了40%。乙烯生物合成响应CdCl处理而增加。CdCl处理后，和的主根长度和根尖长度与野生型相比缩短，表明乙烯在根系对镉胁迫的反应中起作用。在镉胁迫下，和根系中的超氧化物浓度高于野生型幼苗。施加不同浓度（0.01、0.05和0.5μM）的外源1-氨基环丙烷-1-羧酸（ACC，乙烯生物合成的前体）可减少Col-0根尖中超氧化物的积累，并增加镉胁迫下超氧化物歧化酶（SOD）同工酶的活性。5μM的氨基异丁酸AIB（乙烯生物合成抑制剂）可使这一结果逆转。此外，这还伴随着侧根数量和根毛长度的增加，表明乙烯通过SOD同工酶活性控制超氧化物积累，在调节根系发育中起重要作用。野生型植物中镉诱导的超氧化物积累受到抑制，减少了细胞死亡的发生，而根尖区域启动了程序性细胞死亡（PCD），改变了根形态发生（主根长度缩短、侧根和根毛增多），以尽量减少镉胁迫造成的损害，而和幼苗中不存在这种反应。因此，乙烯通过增加SOD同工酶的活性来控制超氧化物积累，在CdCl胁迫期间调节根形态发生。
