PREMISE Soil salinity negatively impacts plant function, development, and yield. To overcome this impediment to agricultural productivity, variation in morphological and physiological response to salinity among genotypes of important crops should be explored. Sorghum bicolor is a staple crop that has adapted to a variety of environmental conditions and contains a significant amount of standing genetic diversity, making it an exemplary species to study variation in salinity tolerance. METHODS Twenty-one diverse Sorghum accessions were treated with nonsaline water or 75 mM sodium chloride. Salinity tolerance was assessed via changes in biomass between control and salt-treated individuals. Accessions were first rank-ordered for salinity tolerance, and then individuals spanning a wide range of responses were analyzed for foliar proline and ion accumulation. Tolerance rankings were then overlaid on a neighbor-joining tree. RESULTS We found that, while proline is often a good indicator of osmotic adjustment and is historically associated with increased salt tolerance in many species, proline accumulation in sorghum reflects a stress response injury rather than acclimation. When combining ion profiles with stress tolerance indices, the variation observed in tolerance was not a sole result of Na+ accumulation, but rather reflected accession-specific mechanisms. CONCLUSIONS We identified significant variation in salinity tolerance among Sorghum accessions that may be a result of the domestication history of Sorghum. When we compared our results with known phylogenetic relationships within sorghum, the most parsimonious explanation for our findings is that salinity tolerance was acquired early during domestication and subsequently lost in accessions growing in areas varying in soil salinity.

中文翻译：

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高粱盐暴露的表型和生理反应揭示了驯化地方品种的多样性

前提 土壤盐分对植物功能、发育和产量产生负面影响。为了克服农业生产力的这一障碍，应该探索重要作物基因型对盐度的形态和生理反应的变化。双色高粱是一种适应各种环境条件的主食作物，并包含大量常设遗传多样性，使其成为研究耐盐性变异的典范物种。方法 用非盐水或 75 mM 氯化钠处理 21 个不同的高粱种质。通过对照和盐处理个体之间生物量的变化来评估耐盐性。种质首先按耐盐性排序，然后对跨越广泛反应的个体进行叶脯氨酸和离子积累的分析。然后将容差排名叠加在邻接树上。结果我们发现，虽然脯氨酸通常是渗透调节的良好指标，并且历史上与许多物种的耐盐性增加有关，但高粱中脯氨酸的积累反映了应激反应损伤而不是适应。当将离子分布与胁迫耐受指数结合时，在耐受性中观察到的变化不是 Na+ 积累的唯一结果，而是反映了加入特定的机制。结论 我们发现高粱种质之间耐盐性存在显着差异，这可能是高粱驯化历史的结果。