Chaturvedi Amit Kumar, Patel Manish Kumar, Mishra Avinash, Tiwari Vivekanand, Jha Bhavanath
Discipline of Marine Biotechnology and Ecology, CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, India.
PLoS One. 2014 Oct 23;9(10):e111379. doi: 10.1371/journal.pone.0111379. eCollection 2014.
Heavy metals are common pollutants of the coastal saline area and Salicornia brachiata an extreme halophyte is frequently exposed to various abiotic stresses including heavy metals. The SbMT-2 gene was cloned and transformed to tobacco for the functional validation. Transgenic tobacco lines (L2, L4, L6 and L13) showed significantly enhanced salt (NaCl), osmotic (PEG) and metals (Zn++, Cu++ and Cd++) tolerance compared to WT plants. Transgenic lines did not show any morphological variation and had enhanced growth parameters viz. shoot length, root length, fresh weight and dry weight. High seed germination percentage, chlorophyll content, relative water content, electrolytic leakage and membrane stability index confirmed that transgenic lines performed better under salt (NaCl), osmotic (PEG) and metals (Zn++, Cu++ and Cd++) stress conditions compared to WT plants. Proline, H2O2 and lipid peroxidation (MDA) analyses suggested the role of SbMT-2 in cellular homeostasis and H2O2 detoxification. Furthermore in vivo localization of H2O2 and O2-; and elevated expression of key antioxidant enzyme encoding genes, SOD, POD and APX evident the possible role of SbMT-2 in ROS scavenging/detoxification mechanism. Transgenic lines showed accumulation of Cu++ and Cd++ in root while Zn++ in stem under stress condition. Under control (unstressed) condition, Zn++ was accumulated more in root but accumulation of Zn++ in stem under stress condition suggested that SbMT-2 may involve in the selective translocation of Zn++ from root to stem. This observation was further supported by the up-regulation of zinc transporter encoding genes NtZIP1 and NtHMA-A under metal ion stress condition. The study suggested that SbMT-2 modulates ROS scavenging and is a potential candidate to be used for phytoremediation and imparting stress tolerance.
重金属是沿海盐碱地区的常见污染物，而极端盐生植物翅碱蓬经常暴露于包括重金属在内的各种非生物胁迫下。克隆了SbMT-2基因并将其转化到烟草中进行功能验证。与野生型植株相比，转基因烟草株系（L2、L4、L6和L13）对盐（NaCl）、渗透（PEG）和金属（Zn++、Cu++和Cd++）的耐受性显著增强。转基因株系未表现出任何形态变异，且生长参数有所提高，即茎长、根长、鲜重和干重。较高的种子发芽率、叶绿素含量、相对含水量、电解质渗漏和膜稳定性指数证实，与野生型植株相比，转基因株系在盐（NaCl）、渗透（PEG）和金属（Zn++、Cu++和Cd++）胁迫条件下表现更好。脯氨酸、H2O2和脂质过氧化（MDA）分析表明SbMT-2在细胞内稳态和H2O2解毒中发挥作用。此外，H2O2和O2-的体内定位以及关键抗氧化酶编码基因SOD、POD和APX的表达升高，证明了SbMT-2在ROS清除/解毒机制中的可能作用。在胁迫条件下，转基因株系根部积累Cu++和Cd++，而茎中积累Zn++。在对照（非胁迫）条件下，根部积累的Zn++更多，但在胁迫条件下茎中Zn++的积累表明SbMT-2可能参与了Zn++从根到茎的选择性转运。金属离子胁迫条件下锌转运蛋白编码基因NtZIP1和NtHMA-A的上调进一步支持了这一观察结果。该研究表明，SbMT-2调节ROS清除，是用于植物修复和赋予胁迫耐受性的潜在候选基因。
