Identification of Salt Stress Biomarkers in Romanian Carpathian Populations of <i>Picea abies</i> (L.) Karst.

The Norway spruce (Picea abies), the most important tree species in European forests, is relatively sensitive to salt and does not grow in natural saline environments. Yet many trees are actually exposed to salt stress due to the common practice of de-icing of mountain roads in winter, using large amounts of NaCl. To help develop strategies for an appropriate use of reproductive seed material on reforestation sites, ensuring better chances of seedling survival in salt-affected areas, we have studied the responses of young spruce seedlings to salt treatments. The specific aim of the work was to identify the optimal salt stress biomarkers in Picea abies, using as experimental material seedlings obtained by germination of seeds with origin in seven populations from the Romanian Carpathian Mountains. These responses included general, conserved reactions such as the accumulation of ions and different osmolytes in the seedlings needles, reduction in photosynthetic pigments levels, or activation of antioxidant systems. Although changes in the contents of different compounds involved in these reactions can be associated to the degree of stress affecting the plants, we propose that the (decreasing) levels of total phenolics or total carotenoids and the (increasing) levels of Na+ or K+ ions in Picea abies needles, should be considered as the most reliable and useful biomarkers for salt stress in this species. They all show very high correlation with the intensity of salt stress, independently of the genetic background of the seeds parental population, and relatively easy, quantitative assays are available to determine their concentrations, requiring simple equipment and little amount of plant material.挪威云杉（Picea abies）是欧洲森林中最重要的乔木树种，对盐胁迫（salt stress）相对敏感，无法在自然盐渍生境中生长。然而，由于冬季山区道路除冰作业常大量施用氯化钠（NaCl），诸多林木实际暴露于盐胁迫环境之中。为制定合理策略以在造林地科学使用繁殖用种子材料，提升受盐渍影响区域的幼苗定植存活率，本研究针对年轻云杉幼苗的盐处理响应展开了探究。本研究的核心目标为鉴定挪威云杉最优的盐胁迫生物标志物（biomarkers），实验材料为取自罗马尼亚喀尔巴阡山脉7个种群的种子萌发获得的幼苗。本研究观测的响应涵盖幼苗针叶内离子与各类渗透调节物质的积累、光合色素水平的下降，以及抗氧化系统的激活等保守性通用反应。尽管参与上述反应的各类化合物含量变化可与植株所受胁迫程度相关联，但我们提出，挪威云杉针叶中总酚类物质或总类胡萝卜素的（下调）水平，以及钠离子（Na+）或钾离子（K+）的（上调）水平，可被视为该物种盐胁迫检测最可靠且实用的生物标志物。此类指标均与盐胁迫强度呈现极高相关性，且不受种子亲本种群的遗传背景影响，同时可通过简便的定量分析方法测定其浓度，仅需简易实验设备与极少量植物组织材料。