Unité de recherche "Ecologie et Dynamique des Systèmes Anthropisés" (EDYSAN, UMR 7058 CNRS-UPJV), 1 rue des Louvels, FR-80037, Amiens Cedex, France.
John Innes Centre, Norwich, NR4 7UH, United Kingdom.
Am J Bot. 2018 Jan;105(1):85-94. doi: 10.1002/ajb2.1014.
Nearly all seed plants rely on stored seed reserves before photosynthesis can commence. Natural selection for seed oil traits must have occurred over 319 million years of evolution since the first seed plant ancestor. Accounting for the biogeographic distribution of seed oil traits is fundamental to understanding the mechanisms of adaptive evolution in seed plants. However, the evolution of seed oils is poorly understood. We provide evidence of the adaptive nature of seed oil traits at the intraspecific and interspecific levels in Brassicaceae-an oilseed-rich and economically important plant family.
Univariate statistics, Pearson's correlation, multiple regression, generalized linear mixed model analysis, and phylogenetic autocorrelation tests on seed oil traits of 360 accessions of Arabidopsis thaliana and 216 Brassicaceae species helped provide evidence of the adaptive nature of seed oil traits.
At higher latitudes, both seed oil content and unsaturated fatty acids have selective advantages in Arabidopsis thaliana (intraspecific-level), while only unsaturated fatty acids have selective advantages across 216 Brassicaceae species (interspecific-level). The seed oil patterns fit within the theoretical framework of the gradient model. Seed oil content increases significantly from temperate to subtropical to tropical regions in Brassicaceae herbs. Absence of phylogenetic signals for seed oil traits and high seed oil content in four tribes of Brassicaceae were observed.
Multiple seed oil traits are adaptive in nature and follow a gradient model. Consistent evolutionary patterns of seed oil traits were observed at the intraspecific and interspecific levels in Brassicaceae. Seed oil traits change with latitude and across biomes, suggesting selection. The absence of a phylogenetic signal for seed oil traits and the occurrence of high seed oil content in four Brassicaceae tribes provides evidence of the adaptive nature of seed oil traits in Brassicaceae.
几乎所有种子植物在光合作用开始之前都依赖于储存的种子储备。自第一个种子植物祖先以来，自然选择对种子油性状的发生必须超过 3.19 亿年的进化。解释种子油性状的生物地理分布对于理解种子植物的适应性进化机制至关重要。然而，种子油的进化仍知之甚少。我们在十字花科植物中提供了种子油性状在种内和种间水平上具有适应性的证据-一种富含油的经济上重要的植物科。
对 360 个拟南芥和 216 个十字花科物种的种子油性状进行单变量统计、皮尔逊相关、多元回归、广义线性混合模型分析和系统发育自相关检验，为种子油性状的适应性提供了证据。
在较高的纬度，种子油含量和不饱和脂肪酸在拟南芥中都具有选择优势（种内水平），而在 216 种十字花科物种中只有不饱和脂肪酸具有选择优势（种间水平）。种子油模式符合梯度模型的理论框架。在十字花科草本植物中，种子油含量从温带显著增加到亚热带，再到热带地区。观察到种子油性状没有系统发育信号，以及四个十字花科族的种子油含量高。
多种种子油性状具有适应性，遵循梯度模型。在十字花科中，种内和种间水平上观察到种子油性状的一致进化模式。种子油性状随纬度和生物群落而变化，表明存在选择。种子油性状没有系统发育信号，以及四个十字花科族的种子油含量高，为十字花科种子油性状的适应性提供了证据。
