Zhang Jing, Duan Xiaohui, Ding Fan, Ma HaiZhen, Zhang Tengguo, Yang Yingli
School of Life Science, Northwest Normal University, Lanzhou, 730070, Gansu, People's Republic of China.
Protoplasma. 2014 Jul;251(4):771-80. doi: 10.1007/s00709-013-0579-7. Epub 2013 Dec 7.
This study aimed to investigate the inhibitory mechanism of root growth and to compare antioxidative responses in two wheat cultivars, drought-tolerant Ningchun and drought-sensitive Xihan, exposed to different NaCl concentrations. Ningchun exhibited lower germination rate, seedling growth, and lipid peroxidation than Xihan when exposed to salinity. The loss of cell viability was correlated with the inhibition of root growth induced by NaCl stress. Moreover, treatments with H2O2 scavenger dimethylthiourea and catalase (CAT) partly blocked salinity-induced negative effects on root growth and cell viability. Besides, the enhancement of superoxide radical and H2O2 levels, and the stimulation of CAT and diamine oxidase (DAO) as well as the inhibition of glutathione reductase (GR) were observed in two wheat roots treated with salinity. However, hydroxyl radical content increased only in Xihan roots under NaCl treatment, and the changes of soluble peroxidase (POD), ascorbate peroxidase (APX), superoxide dismutase (SOD), and cell-wall-bound POD activities were different in drought-tolerant Ningchun and drought-sensitive Xihan exposed to different NaCl concentrations. In conclusion, salinity might induce the loss of cell viability via a pathway associated with extracellular H2O2 generation, which was the primary reason leading to the inhibition of root growth in two wheat cultivars. Here, it was also suggested that increased H2O2 accumulation in the roots of drought-tolerant Ningchun might be due to decreased POD and GR activities as well as enhanced cell-wall-bound POD and DAO ones, while the inhibition of APX and GR as well as the stimulation of SOD and DAO was responsible for the elevation of H2O2 level in drought-sensitive Xihan roots.
本研究旨在探究根系生长的抑制机制，并比较耐旱品种宁春和干旱敏感品种西旱在不同氯化钠浓度处理下的抗氧化反应。在盐胁迫下，宁春的发芽率、幼苗生长和脂质过氧化程度均低于西旱。细胞活力的丧失与氯化钠胁迫诱导的根系生长抑制相关。此外，用H2O2清除剂二甲基硫脲和过氧化氢酶（CAT）处理可部分阻断盐胁迫对根系生长和细胞活力的负面影响。此外，在盐处理的两个小麦根系中观察到超氧自由基和H2O2水平升高，CAT和二胺氧化酶（DAO）活性增强以及谷胱甘肽还原酶（GR）活性受到抑制。然而，仅在氯化钠处理下的西旱根系中羟基自由基含量增加，在不同氯化钠浓度处理下，耐旱品种宁春和干旱敏感品种西旱的可溶性过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）、超氧化物歧化酶（SOD）和细胞壁结合POD活性的变化有所不同。总之，盐胁迫可能通过与细胞外H2O2产生相关的途径诱导细胞活力丧失，这是导致两个小麦品种根系生长受抑制的主要原因。此外，耐旱品种宁春根系中H2O2积累增加可能是由于POD和GR活性降低以及细胞壁结合POD和DAO活性增强所致，而干旱敏感品种西旱根系中H2O2水平升高则是由于APX和GR受到抑制以及SOD和DAO活性增强所致。
