With rising food demands, crop production on salinized lands is increasingly necessary. Sunflower (Helianthus annuus), a moderately salt-tolerant crop, exhibits a tradeoff where more vigorous, high-performing genotypes have a greater proportional decline in biomass under salinity stress. Prior research has found deviations from this relationship across genotypes. Here, we identified the traits and genomic regions underlying variation in this expectation-deviation tolerance (the magnitude and direction of deviations from the expected effect of salinity). We grew a sunflower diversity panel under control and salt-stressed conditions and measured a suite of morphological (growth, mass allocation, plant and leaf morphology) and leaf ionomic traits. The genetic basis of variation and plasticity in these traits was investigated via genome-wide association, which also enabled the identification of genomic regions (i.e. haplotypic blocks) influencing multiple traits. We found that the magnitude and direction of plasticity in whole-root mass fraction, fine root mass fraction, and chlorophyll content, as well as leaf sodium and potassium content under saline conditions, were most strongly correlated with expectation-deviation tolerance. We identified multiple genomic regions underlying these traits as well as a single alpha-mannosidase gene directly associated with this tolerance metric. Our results show that, by taking the vigor-salinity effect tradeoff into account, we can identify unique traits and genes associated with salinity tolerance. Since these traits and genomic regions are distinct from those associated with high vigor (i.e. growth in benign conditions), they provide an avenue for increasing salinity tolerance in high-performing sunflower genotypes without compromising vigor.

随着粮食需求的增加，在盐化土地上种植作物变得越来越必要。向日葵（ Helianthus annuus ）是一种中等耐盐作物，表现出一种权衡，即在盐胁迫下，更有活力、高性能的基因型的生物量下降比例更大。先前的研究发现不同基因型之间的这种关系存在偏差。在这里，我们确定了这种期望偏差耐受性（与盐度预期影响的偏差的大小和方向）变化背后的性状和基因组区域。我们在对照和盐胁迫条件下培养了向日葵多样性小组，并测量了一系列形态学（生长、质量分配、植物和叶子形态）和叶子离子组学特征。通过全基因组关联研究了这些性状变异和可塑性的遗传基础，这也使得能够识别影响多个性状的基因组区域（即单倍型块）。我们发现，盐分条件下全根质量分数、细根质量分数、叶绿素含量以及叶片钠和钾含量的可塑性大小和方向与期望偏差耐受性密切相关。我们确定了这些性状背后的多个基因组区域以及与该耐受性指标直接相关的单个α-甘露糖苷酶基因。我们的结果表明，通过考虑活力-盐度效应权衡，我们可以识别与耐盐性相关的独特性状和基因。由于这些性状和基因组区域不同于那些与高活力相关的性状和基因组区域（即 在良性条件下生长），它们为提高高性能向日葵基因型的耐盐性提供了途径，同时又不影响活力。