He Li, Wang Xiaomin, Feng Ruijun, He Qiang, Wang Shengwang, Liang Cuifang, Yan Lili, Bi Yurong
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, China.
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, Qinghai 810016, China.
Plants (Basel). 2019 Nov 29;8(12):557. doi: 10.3390/plants8120557.
Alternative pathway (AP) has been widely accepted to be involved in enhancing tolerance to various environmental stresses. In this study, the role of AP in response to cadmium (Cd) stress in two barley varieties, highland barley (Kunlun14) and barley (Ganpi6), was investigated. Results showed that the malondialdehyde (MDA) content and electrolyte leakage (EL) level under Cd stress increased in two barley varieties. The expressions of alternative oxidase () genes (mainly ), AP capacity (V), and AOX protein amount were clearly induced more in Kunlun14 under Cd stress, and these parameters were further enhanced by applying sodium nitroprussid (SNP, a NO donor). Moreover, HO and O contents were raised in the Cd-treated roots of two barley varieties, but they were markedly relieved by exogenous SNP. However, this mitigating effect was aggravated by salicylhydroxamic acid (SHAM, an AOX inhibitor), suggesting that AP contributes to NO-enhanced Cd stress tolerance. Further study demonstrated that the effect of SHAM application on reactive oxygen species (ROS)-related scavenging enzymes and antioxidants was minimal. These observations showed that AP exerts an indispensable function in NO-enhanced Cd stress tolerance in two barley varieties. AP was mainly responsible for regulating the ROS accumulation to maintain the homeostasis of redox state.
交替途径（AP）已被广泛认为参与增强对各种环境胁迫的耐受性。在本研究中，研究了AP在两个大麦品种，即青稞（昆仑14）和大麦（甘啤6）中对镉（Cd）胁迫响应中的作用。结果表明，在Cd胁迫下，两个大麦品种的丙二醛（MDA）含量和电解质渗漏（EL）水平均升高。在Cd胁迫下，昆仑14中交替氧化酶（AOX）基因（主要是 ）的表达、AP容量（V）和AOX蛋白量明显诱导更多，并且通过施用硝普钠（SNP，一种NO供体）进一步增强了这些参数。此外，两个大麦品种Cd处理根中的H₂O₂和O₂⁻含量升高，但外源SNP明显缓解了这些情况。然而，水杨基羟肟酸（SHAM，一种AOX抑制剂）加剧了这种缓解作用，表明AP有助于NO增强的Cd胁迫耐受性。进一步研究表明，施用SHAM对活性氧（ROS）相关清除酶和抗氧化剂的影响最小。这些观察结果表明，AP在两个大麦品种中NO增强的Cd胁迫耐受性中发挥不可或缺的作用。AP主要负责调节ROS积累以维持氧化还原状态的稳态。
