Abstract Quinoa (Chenopodium quinoa Willd.) is a facultative halophyte which has taken great importance in recent years due to the nutritional characteristics of its seed. In environments with moderate to high salinity, both the decrease in water potential and the accumulation of Na+ and Cl− ions can constitute stress factors that limit germination and seedling establishment. In the present study, we investigated the influence of NaCl solutions (ranging from 0 to 400 mM) on different components of the antioxidant metabolism during seed germination and seedling emergence, in three quinoa genotypes (CICA, Villarrica and Chadmo) differing in their germination responses and tolerance to salinity. To further explore the mechanisms involved, seed coat characteristics were microscopically analyzed, and seed hydration rates together with changes in the distribution of different ions in selected seed tissues were monitored. Finally, because the effect of NaCl on the accumulation of betalains in young seedlings differed among genotypes, the role of these pigments in salt stress tolerance was also investigated. Among the three genotypes, CICA was the most tolerant as indicated by its higher maximum and normal germination percentages at the highest salt levels tested. Surprisingly, this response was not correlated to the activity profile of antioxidant enzymes, most of which were up-regulated to a larger extent in the less tolerant genotype (Chadmo). Rather, seed coat characteristics that favor a rapid hydration rate, together with mechanisms aimed at preventing excess osmotic and ionic imbalances seem to play a predominant role. Interestingly, the presence of salt decreased the concentration of betalains in the seedlings, though to a lesser extent in CICA than in the other two genotypes. The down-regulation of their synthesis through germination under complete darkness, impaired the percentage of normal germination and increased lipid peroxidation in CICA seedlings exposed to 300 mM NaCl, indicating that these pigments may also contribute to salt stress tolerance.

中文翻译：

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藜野生藜萌发和幼苗早期生长过程中的耐盐机制。对盐胁迫具有不同敏感性的基因型

摘要 藜麦（Chenopodium quinoa Willd.）是一种兼性盐生植物，由于其种子的营养特性，近年来备受重视。在中到高盐度的环境中，水势的降低和 Na+ 和 Cl- 离子的积累都可以构成限制发芽和幼苗建立的胁迫因素。在本研究中，我们研究了 NaCl 溶液（从 0 到 400 mM）对种子萌发和幼苗出苗过程中抗氧化代谢的不同成分的影响，在三种藜麦基因型（CICA、Villarrica 和 Chadmo）中，它们的萌发反应不同和耐盐性。为了进一步探索所涉及的机制，对种皮特性进行了显微镜分析，和种子水合速率以及选定种子组织中不同离子分布的变化进行了监测。最后，由于 NaCl 对幼苗中甜菜碱积累的影响因基因型而异，因此还研究了这些色素在盐胁迫耐受性中的作用。在三种基因型中，CICA 是最耐受的，正如其在测试的最高盐水平下具有较高的最大和正常发芽百分比所表明的那样。令人惊讶的是，这种反应与抗氧化酶的活性谱无关，其中大多数在耐受性较差的基因型 (Chadmo) 中被更大程度地上调。相反，有利于快速水合速率的种皮特性以及旨在防止过度渗透和离子失衡的机制似乎起着主要作用。有趣的是，盐的存在降低了幼苗中甜菜素的浓度，但在 CICA 中的程度低于其他两种基因型。通过在完全黑暗下发芽，它们的合成下调，在暴露于 300 mM NaCl 的 CICA 幼苗中，正常发芽率受损，脂质过氧化增加，表明这些色素也可能有助于盐胁迫耐受性。