College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian 271018, China.
Department of Horticulture, ALS 4017, Oregon State University, Corvallis, OR 97331, USA.
Plant Sci. 2017 Apr;257:74-83. doi: 10.1016/j.plantsci.2017.01.012. Epub 2017 Jan 24.
Tomato (Solanum lycopersicum cv. 'Moneymaker') was transformed with the choline oxidase gene codA from Arthrobacter globiformis, which was modified to allow for targeting to both chloroplasts and the cytosol. Glycine betaine (GB) was accumulated in transformed plants, while no detectable GB was found in wild-type (WT) plants. Compared to WT plants, transgenic lines showed significantly higher photosynthetic rates (Pn) and antioxidant enzyme activities and lower reactive oxygen species (ROS) accumulation in the leaves when exposed to salt stress. Furthermore, compared with WT plants, K efflux decreased and Na efflux increased in roots of transgenic plants under salt stress; resulted in lower Na/K ratios in transgenic lines. The exogenous application of GB also significantly reduced NaCl-induced K efflux and increased Na efflux in WT plants. A qRT-PCR assay indicated that GB enhanced NaCl-induced expression of genes encoding the K transporter, Na/H antiporter, and H-ATPase. These results suggest that the enhanced salt tolerance conferred by codA in transgenic tomato plants might be due to the regulation of ion channel and transporters by GB, which would allow high potassium levels and low sodium levels to be maintained in transgenic plants under salt stress condition.
番茄（Solanum lycopersicum cv. 'Moneymaker'）被来自球形节杆菌（Arthrobacter globiformis）的胆碱氧化酶基因 codA 转化，该基因经过修饰后可以靶向叶绿体和细胞质。在转化的植物中积累了甘氨酸甜菜碱（GB），而在野生型（WT）植物中则没有检测到 GB。与 WT 植物相比，在盐胁迫下，转基因株系的光合速率（Pn）和抗氧化酶活性显著提高，活性氧（ROS）积累降低。此外，与 WT 植物相比，在盐胁迫下，转基因植物根系中 K 外流减少，Na 外流增加，导致转基因株系中的 Na/K 比值降低。外源 GB 的应用也显著降低了 WT 植物中 NaCl 诱导的 K 外流，增加了 Na 外流。qRT-PCR 检测表明，GB 增强了编码 K 转运体、Na/H 反向转运体和 H-ATP 酶的基因的 NaCl 诱导表达。这些结果表明，转基因番茄中 codA 赋予的耐盐性增强可能是由于 GB 对离子通道和转运体的调节，这使得转基因植物在盐胁迫条件下能够维持较高的钾水平和较低的钠水平。
