Data from: Patterns of domestication in the Ethiopian oil-seed crop Noug (Guizotia abyssinica)

Noug (Guizotia abyssinica) is a semi-domesticated oil-seed crop, which is primarily cultivated in Ethiopia. Unlike its closest crop relative, sunflower, noug has small seeds, small flowering heads, many branches, many flowering heads, indeterminate flowering, and it shatters in the field. Here we conducted common garden studies and microsatellite analyses of genetic variation to test whether high levels of crop-wild gene flow and/or unfavorable phenotypic correlations have hindered noug domestication. With the exception of one population, analyses of microsatellite variation failed to detect substantial recent admixture between noug and its wild progenitor. Likewise, only very weak correlations were found between seed mass and the number or size of flowering heads. Thus, noug’s ‘atypical’ domestication syndrome does not seem to be a consequence of recent introgression or unfavorable phenotypic correlations. Nonetheless, our data do reveal evidence of local adaptation of noug cultivars to different precipitation regimes, as well as high levels of phenotypic plasticity, which may permit reasonable yields under diverse environmental conditions. Why noug has not been fully domesticated remains a mystery, but perhaps early farmers selected for resilience to episodic drought or untended environments rather than larger seeds. Domestication may also have been slowed by noug’s outcrossing mating system.

油蓟（Noug，学名Guizotia abyssinica）是一种半驯化油料作物，主要栽培于埃塞俄比亚。与其近缘栽培作物向日葵不同，油蓟具有种子细小、花序小巧、分枝繁多、花序数量丰富、无限开花习性以及田间易落粒的特性。本研究通过同质园试验（common garden studies）与微卫星（microsatellite）遗传变异分析，旨在探究高水平的栽培-野生基因流，抑或不利的表型相关性，是否阻碍了油蓟的驯化进程。除单个种群外，微卫星变异分析未检测到油蓟与其野生祖先间存在显著的近期遗传混合事件。同样，种子质量与花序数量、花序大小之间仅存在极微弱的相关性。由此可见，油蓟“非典型”的驯化综合征（domestication syndrome）似乎并非由近期遗传渐渗（introgression）或不利表型相关性所导致。尽管如此，本研究数据仍揭示了油蓟栽培种对不同降水格局的本地适应证据，同时其表型可塑性（phenotypic plasticity）极高，这使其可在多样的环境条件下维持可观的产量。油蓟尚未完成完全驯化的原因仍有待解析，但早期农民或许更倾向于选择适应间歇性干旱或粗放管理环境的株系，而非大种子材料。此外，油蓟的异交交配系统（outcrossing mating system）或许也延缓了其驯化进程。