ABSTRACTSalt tolerance can be assessed with plant morphological and physiological traits. This study evaluated the salt tolerance of eight transgenic potato (Solanum tuberosum L.) lines using an integrated evaluation index where plant height, leaf area expansion rate, survival rate, and tuber yield were integrated. We hypothesized that (i) the integration of several plant growth traits produced a comprehensive evaluation of salt tolerance, and (ii) the level of salt tolerance in potato was also related to their physiological responses such as chlorophyll and proline contents. A greenhouse study was conducted at Gansu Agricultural University in 2011. Transgenic potato lines carrying AtNHX1 gene expressed significantly higher levels of salt tolerance than the nontransgenic check. The integrated evaluation index showed that the NG‐5 transgenic line had a salt‐tolerance level 46 times that of the check. The check plants had a lower tuber yield when NaCl concentration was 3.3 g L−1 and more than one‐half of the plants died when NaCl concentration was 6.5 g L−1. The thresholds ranged between 3.7 and 6.8 g L−1 and the half‐lethal (LD50) NaCl concentration varied from 8.7 to 14.6 g L−1 for transgenic lines. By Day 40 after salt‐stress challenges at 9 g L−1 NaCl, total chlorophyll content decreased 32% in the check but by an average of 14% in the transgenic lines, whereas proline content in the check was 2.5 times those in the transgenic lines. The integrated evaluation index provided an adequate, quantitative assessment of salt tolerance of potato and can be used effectively in the development of salt‐tolerant cultivars.

The tobacco plantlets in Vitro were treated with different concentrations of NaCl in 20 days.The result indicated that the plant growth was retarded steadily with the increase of salt concentration;In this case,the content of K+ reduced and the content of Na+ increased in root,stem and leaf;In leaf,content of chlorophyll reduced,but the content of malonaldehyde(MDA),membrane permeability and proline increased,moreover the content of proline showed significant positive correlation with the content of malonaldehyde(MDA) and membrane permeability.It showed that the accumulative content of praline could reflect the tobacco plantlets' hurt degree.The study indicated that either the hurt of ion,the increase of membrane permeability or the reduction of chlorophyll affected the growth of tobacco plantlets in vitro of salt treatment.

The potato cultivar Atlantic plantlets in vitro were treated with different concentrations of NaCl for 20 days.The results indicated that with more salt concentration the content of Na+ was increased dramatically,the content of K+ was stable and Na+/K+ was increased significantly in the root and stem.In the leaf,the content of chlorophyll reduced,but the content of Malonaldehyde(MDA),membrane permeability and proline increased.Moreover,the content of proline was highly significantly correlated to the content of MDA and membrane permeability at a range of concentrations of NaCl,suggesting that the accumulation of proline could reflect the degree the plantlets in vitro got hurt.These reaults indicated that accumulated Na+,increase in membrane permeability and reduction in chlorophyll were the main effects on the growth of potato plantlets in vitro under salt stress.

Potato microtubers of Atlantic,Longshu3 and Gannongshu2 were induced by use of 5 mediums and 3 culture methods.The result showed that 8 percent sucrose was the best concentration of inducing Atlantic and Longshu3's microtuber;5mg/L 6-BA add could improve the rate of microtuber setting and increase microtuber's diameter;In the 8 percent sucrose medium,agar didn't affect the rate of microtuber inducing;In the MS medium of no sucrose,300μmol/L sorbitol add with 20mmol/L NH4NO3 and 20mmol/L KNO3 was harmful to formation and growth of microtuber;In the 3 methods,liquid method was the best method in inducing microtuber.

本研究用不同NaCl浓度盐溶液处理马铃薯"甘农薯2号"（对照） 和转拟南芥液泡膜Na+/H+逆向转运蛋白基因（AtNHX1）不同株系幼苗，综合评价对照和转基因株系耐盐性，筛选高耐盐转基因株系，探索AtNHX1基因提高马铃薯耐盐能力的效应。结果表明：运用聚类分析法和标准差系数赋予权重法综合评价各株系耐盐性，筛选出1个强耐盐株系NG-5和4个较强耐盐株系NG-6、NG-7、NG-8、NG-2，各株系耐盐性由强至弱为NG-5＞NG-6＞NG-7＞NG-8＞NG-2＞NG-1＞NG-4＞NG-3>CK；用单株产量和存活率分别与NaCl浓度建立回归方程，以单株产量和存活率下降50%求得耐盐阙值和半致死浓度，强耐盐株系NG-5 的耐盐阙值为0.68%，半致死浓度为1.46%；在此基础上，进一步探讨了盐胁迫下高耐盐株系的生理反应，随盐浓度的增加，转基因各株系叶片叶绿素含量下降幅度、脯氨酸和Na+含量上升幅度均明显低于对照，转基因株系叶片中维持着较高的K+/Na+，说明AtNHX1的导入能够显著提高马铃薯的耐盐性。