Institute of Vegetables, Wuhan Academy of Agricultural Sciences, Wuhan, Hubei, China.
PLoS One. 2021 Jul 6;16(7):e0249825. doi: 10.1371/journal.pone.0249825. eCollection 2021.
The water dropworts Oenanthe linearis Wall. ex DC. and O. javanica (Blume) DC. are aquatic perennial herbs that have been used in China as vegetables and traditional medicines. However, their phylogenetic relationships and genetic diversity are poorly understood. Here, we presented the phenotypic traits and genome-wide DNA marker-based analysis of 158 water dropwort accessions representing both species. The analysis revealed that Oenanthe linearis was readily segregated into linear-leaf and deep-cleft leaf water dropworts according to their leaf shapes at flowering. Oenanthe javanica was classified by clustering analysis into two clusters based mainly on the morphological characteristics of their ultimate segments (leaflets). A set of 11 493 high-quality single-nucleotide polymorphisms was identified and used to construct a phylogenetic tree. There was strong discrimination between O. linearis and O. javanica, which was consistent with their phenotype diversification. The population structure and phylogenetic tree analyses suggested that the O. linearis accessions formed two major groups, corresponding to the linear-leaf and deep-cleft leaf types. The most obvious phenotypic differences between them were fully expressed at the reproductive growth stage. A single-nucleotide polymorphism-based analysis revealed that the O. javanica accessions could be categorized into groups I andII. However, this finding did not entirely align with the clusters revealed by morphological classification. Landraces were clustered into one group along with the remaining wild accessions. Hence, water dropwort domestication was short in duration. The level of genetic diversity for O. linearis (π = 0.1902) was slightly lower than that which was estimated for O. javanica (π = 0.2174). There was a low level of genetic differentiation between O. linearis and O. javanica (Fst = 0.0471). The mean genetic diversity among accessions ranged from 0.1818 for the linear-leaf types to 0.2318 for the groupII accessions. The phenotypic traits and the single-nucleotide polymorphism markers identified here lay empirical foundation for future genomic studies on water dropwort.
水芹（Oenanthe linearis Wall. ex DC.）和短梗水芹（O. javanica (Blume) DC.）是两种水生多年生草本植物，在中国被用作蔬菜和传统药材。然而，它们的系统发育关系和遗传多样性尚未得到充分了解。在这里，我们对代表这两个物种的 158 份水芹进行了表型特征和基于全基因组 DNA 标记的分析。分析表明，水芹根据开花时的叶片形状可分为线状叶和深裂叶水芹。短梗水芹根据其末级段（小叶）的形态特征聚类分析分为两个聚类。共鉴定出 11493 个高质量的单核苷酸多态性（SNP），并用于构建系统发育树。线性叶和短梗水芹之间存在强烈的分化，这与它们的表型多样化一致。种群结构和系统发育树分析表明，水芹的供试品系形成了两个主要群体，分别对应于线状叶和深裂叶类型。它们之间最明显的表型差异在生殖生长阶段完全表现出来。基于 SNP 的分析表明，短梗水芹供试品系可分为 I 组和 II 组。然而，这一发现与形态分类揭示的聚类并不完全一致。地方品种与其余野生供试品系聚类在一起。因此，水芹的驯化时间很短。线性叶水芹的遗传多样性水平（π = 0.1902）略低于短梗水芹（π = 0.2174）。线性叶水芹和短梗水芹之间的遗传分化程度较低（Fst = 0.0471）。供试品系间的平均遗传多样性范围从线状叶类型的 0.1818 到 II 组的 0.2318。这里鉴定的表型特征和 SNP 标记为水芹的未来基因组研究奠定了经验基础。
