Data from: Genomic regions associate with major axes of variation driven by gas exchange and leaf construction traits in cultivated sunflower (Helianthus annuus L.)

Stomata and leaf veins play an essential role in transpiration and the movement of water throughout leaves. These traits are thus thought to play a key role in the adaptation of plants to drought and a better understanding of the genetic basis of their variation and coordination could inform efforts to improve drought tolerance. Here, we explore patterns of variation and covariation in leaf anatomical traits and analyze their genetic architecture via genome-wide association (GWA) analyses in cultivated sunflower (Helianthus annuus L.). Traits related to stomatal density and morphology as well as lower order veins were manually measured from digital images while the density of minor veins was estimated using a novel deep learning approach. Leaf, stomatal, and vein traits exhibited numerous significant correlations that generally followed expectations based on functional relationships. Correlated suites of traits could further be separated along three major principal component (PC) axes that were heavily influenced by variation in traits related to gas exchange, leaf hydraulics, and leaf construction. While there was limited evidence of colocalization when individual traits were subjected to GWA analyses, major multivariate PC axes that were most strongly influenced by several traits related to gas exchange or leaf construction did exhibit significant genomic associations. These results provide insight into the genetic basis of leaf trait covariation and showcase potential targets for future efforts aimed at modifying leaf anatomical traits in sunflower.

气孔（stomata）与叶脉在植物蒸腾作用及叶片内水分运输过程中发挥着至关重要的作用。因此，这些性状被认为在植物适应干旱的过程中扮演关键角色；若能更深入解析其变异与协同调控的遗传基础，将可为提升作物抗旱性的育种工作提供理论指导。本研究以栽培向日葵（Helianthus annuus L.）为材料，探究叶片解剖性状的变异与协同变化模式，并通过全基因组关联分析（GWA）解析其遗传架构。针对气孔密度、气孔形态以及低级叶脉的相关性状，研究人员从数码图像中手动测量；而细脉密度则采用全新的深度学习方法进行估算。叶片、气孔及叶脉相关性状呈现出大量显著关联，且这些关联整体符合基于功能关系的预期。具有协同关联的性状簇可进一步沿三大主成分（PC）轴进行区分，这些主成分轴主要受气体交换、叶片水力特性及叶片结构相关性状的变异影响。尽管对单个性状开展GWA分析时，仅能找到少量共定位的证据，但受气体交换或叶片结构相关性状强烈影响的主要多变量PC轴，却呈现出显著的基因组关联信号。本研究结果解析了叶片性状协同变化的遗传基础，并为未来通过改造向日葵叶片解剖性状以优化其抗旱性的相关工作，提供了潜在的靶标方向。