Euphorbia mongoliensis (Euphorbiaceae), a new species from Inner Mongolia, China

In May 2020, a new taxon of Euphorbia, Euphorbiaceae was collected from a dry hillside of Dongsheng District, Ordos City, Inner Mongolia. The morphological characteristics of the specimens analyzed differ from those of the known Euphorbia species from this region; therefore, we suspected this may be a new species, and we set to analyze the ITS2 sequences of some Euphorbia species. The results show that the new taxon belongs to the sect. Esula of Euphorbia subg. Esula. It is similar to Euphorbia esula (description from Flora of China) but does not belong to the same species. Concomitantly, plant morphological data and pollen morphology results show significant differences between the new taxon, E. esula and E. caesia, a finding that supports the delimitation of this new taxon, which is named Euphorbia mongoliensis in accordance with its geographical distribution.

Discrimination of leafy spurge (Euphorbia esula) and purple loosestrife (Lythrum salicaria) based on field spectral data

Leafy spurge (Euphorbia esula L.) and purple loosestrife (Lythrum salicaria L.) are invasive weeds that displace native vegetation. Herbicides are often applied to these weeds during flowering, so it would be ideal to identify them early in the season, possibly by the leaves. This paper evaluates the spectral separability of the inflorescences and leaves of these plants from surrounding vegetation. Leafy spurge, purple loosestrife, and surrounding vegetation were collected from sites in southeastern North Dakota and subjected to spectral analysis. Partial least-squares discriminant analysis (PLS-DA) was used to separate the spectral signatures of these weeds in the visible and near-infrared wavelengths. Using PLS-DA, the weeds were discriminated from their surroundings with R2 values of 0.86 to 0.92. Analysis of the data indicated that the bands contributing the most to each model were in the red and red-edge spectral regions. Identifying these weeds by the leaves allows them to be mapped earlier in the season, providing more time for herbicide application planning. The spectral signatures identified in this proof of concept study are the first step before using ultra–high resolution aerial imagery to classify and identify leafy spurge and purple loosestrife.

Gene Space and Transcriptome Assemblies of Leafy Spurge (Euphorbia esula) Identify Promoter Sequences, Repetitive Elements, High-Quality Markers, and a Full-Length Chloroplast Genome

Leafy spurge (Euphorbia esulaL.) is an invasive perennial weed infesting range and recreational lands of North America. Previous research and omics projects withE. esulahave helped develop it as a model for studying many aspects of perennial plant development and response to abiotic stress. However, the lack of an assembled genome forE. esulahas limited the power of previous transcriptomics studies to identify functional promoter elements and transcription factor binding sites. An assembled genome forE. esulawould enhance our understanding of signaling processes controlling plant development and responses to environmental stress and provide a better understanding of genetic factors impacting weediness traits, evolution, and herbicide resistance. A comprehensive transcriptome database would also assist in analyzing future RNA-seq studies and is needed to annotate and assess genomic sequence assemblies. Here, we assembled and annotated 56,234 unigenes from an assembly of 589,235 RNA-seq-derived contigs and a previously published Sanger-sequenced expressed sequence tag collection. The resulting data indicate that we now have sequence for >90% of the expressedE. esulaprotein-coding genes. We also assembled the gene space ofE. esulaby using a limited coverage (18X) genomic sequence database. In this study, the programs Velvet and Trinity produced the best gene-space assemblies based on representation of expressed and conserved eukaryotic genes. The results indicate thatE. esulacontains as much as 23% repetitive sequences, of which 11% are unique. Our sequence data were also sufficient for assembling a full chloroplast and partial mitochondrial genome. Further, marker analysis identified more than 150,000 high-quality variants in ourE. esulaL-RNA–scaffolded, whole-genome, Trinity-assembled genome. Based on these results,E. esulaappears to have limited heterozygosity. This study provides a blueprint for low-cost genomic assemblies in weed species and new resources for identifying conserved and novel promoter regions among coordinately expressed genes ofE. esula.