Species in the genera Hyaloperonospora and Peronospora (Oomycota, Peronosporaceae) are obligate biotrophic pathogens responsible for destructive downy mildew diseases of ornamental horticulture plants worldwide. Throughout the past decade, newly emergent downy mildew diseases have become increasingly prevalent, but often the identity of the pathogen is unknown or poorly defined. In this study we set out to identify the downy mildew pathogens infecting three widely grown ornamental plants: Agastache spp. (hyssops), Tarenaya hassleriana (syn. = Cleome hassleriana; spider-flower) and Monarda didyma (bee balm or bergamot). Phylogenetic analysis of the internal transcribed spacer rDNA and cox2 revealed two new species, which are described here as Peronospora monardae infecting both Monarda didyma and A. mexicana, and Hyaloperonospora daughtreyae infecting T. hassleriana. One sample of Peronospora collected from Agastache sp. ‘Bolero’ did not cluster with P. monardae, but its relationship to other species in the clade was not sufficiently resolved for taxonomic determination. Phylogenetic analysis also supported the combination of Peronospora iberidis, a pathogen of Iberis spp. (candytuft), into Hyaloperonospora. To assess intrasample ITS sequence variation from P. monardae, data were generated using high-throughput amplicon sequencing (HTAS). Multiple haplotypes were identified from the P. monardae samples, with less than 1% intrasample variation observed. From a core set of haplotypes shared across the HTAS the variant frequencies could not be completely explained by heterozygosity alone.

Hyaloperonospora和Peronospora属（Oomycota，Peronosporaceae）中的物种是专性的生物营养病原体，负责全球观赏园艺植物的霜霉病病害。在过去的十年中，新近出现的霜霉病已变得越来越普遍，但是病原体的身份常常是未知的或定义不清的。在这项研究中，我们着手确定感染三种广泛生长的观赏植物：Ag香属的霜霉病病原体。（牛膝草），Tarenaya hassleriana（合成=  Cleome hassleriana ;蜘蛛花）和Monarda didyma（蜂香膏或佛手柑）。所述内转录间隔区rDNA和系统发育分析的cox 2揭示了两个新的物质，其在这里被描述为霜霉monardae感染既大红香蜂草和A.墨西哥，和Hyaloperonospora daughtreyae感染T. hassleriana。从Agastache sp。收集的Peronospora的一个样品。'Bolero'不能与P. monardae聚簇，但是它与进化枝中其他物种的关系尚未得到足够的分类学确定。系统发育分析还支持埃博拉氏菌病原体的组合。屈曲花属属。（candytuft），放入透明质酸孢子中。为了评估从intrasample ITS序列变异P. monardae，使用高通量测序的扩增子（HTA的）产生的数据。从莫氏疟原虫样品中鉴定出多种单倍型，观察到的样品内变异小于1％。从跨HTAS共享的一组核心单倍型来看，仅通过杂合性不能完全解释变异频率。