Taraxacum kok-saghyz (TKS) carries great potential as alternative natural rubber source. To better inform future breeding efforts with TKS and gain a deeper understanding of its genetic diversity, we utilized de novo sequencing to generate novel genomic simple sequence repeats markers (gSSRs). We utilized 25 gSSRs on a collection of genomic DNA (gDNA) samples from germplasm bank, and two gDNA samples from historical herbarium specimens. PCR coupled with capillary electrophoresis and an array of population genetics tools were employed to analyze the dataset of our study as well as a dataset of the recently published genic SSRs (eSSRs) generated on the same germplasm. Our results using both gSSRs and eSSRs revealed that TKS has low- to- moderate genetic diversity with most of it partitioned to the individuals and individuals within populations, whereas the species lacked population structure. Nineteen of the 25 gSSR markers cross-amplified to other Taraxacum spp. collected from Southeastern United States and identified as T. officinale by ITS sequencing. We used a subset of 14 gSSRs to estimate the genetic diversity of the T. officinale gDNA collection. In contrast to the obligatory outcrossing TKS, T. officinale presented evidence for population structure and clonal reproduction, which agreed with the species biology. We mapped the molecular markers sequences from this study and several others to the well-annotated sunflower genome. Our gSSRs present a functional tool for the biodiversity analyses in Taraxacum, but also in the related genera, as well as in the closely related tribes of the Asteraceae.

BACKGROUND Poa annua is a pervasive grassy, self‐pollinating, weed that has evolved resistance to 10 different herbicide modes‐of‐action, third most of all weed species. We investigated constitutive overexpression of genes associated with non‐target site resistance (NTSR) in POAAN‐R3 and the response of those genes when treated with trifloxysulfuron despite the biotype having a known target site mutation in acetolactate synthase (ALS). RESULTS Despite having an ALS target site mutation, POAAN‐R3 still had a transcriptomic response to herbicide application that differed from a susceptible biotype. We observed differential expression of genes associated with transmembrane transport and oxidation–reduction activities, with differences being most pronounced prior to herbicide treatment. CONCLUSIONS In the P. annua biotype we studied with confirmed target site resistance to ALS inhibitors, we also observed constitutive expression of genes regulating transmembrane transport, as well as differential expression of genes associated with oxidative stress after treatment with trifloxysulfuron. This accumulation of mechanisms, in addition to the manifestation of target site resistance, could potentially increase the chance of survival when plants are challenged by different modes of action.

Cornus kousa (Asian dogwood), an East Asia native tree, is the most economically important species of the dogwood genus, owing to its desirable horticultural traits and ability to hybridize with North America‐native dogwoods. To assess the species genetic diversity and to better inform the ongoing and future breeding efforts, we assembled an herbarium and arboretum collection of 131 noncultivated C. kousa specimens. Genotyping and capillary electrophoresis analyses of our C. kousa collection with the newly developed genic and published nuclear genomic microsatellites permitted assessment of genetic diversity and evolutionary history of the species. Regardless of the microsatellite type used, the study yielded generally similar insights into the C. kousa diversity with subtle differences deriving from and underlining the marker used. The accrued evidence pointed to the species distinct genetic pools related to the plant country of origin. This can be helpful in the development of the commercial cultivars for this important ornamental crop with increased pyramided utility traits. Analyses of the C. kousa evolutionary history using the accrued genotyping datasets pointed to an unsampled ancestor population, possibly now extinct, as per the phylogeography of the region. To our knowledge, there are few studies utilizing the same gDNA collection to compare performance of genomic and genic microsatellites. This is the first detailed report on C. kousa species diversity and evolutionary history inference.

The genus Chrysogonum is native to the eastern United States. Three entities have been recognized-either as three varieties of Chrysogonum virginianum or as two species, one of them with two varieties. The current study suggests that a fourth entity should be recognized. Several forms of the complex are in commercial trade as ornamentals. As very limited molecular information on Chrysogonum is available, we developed a set of genic simple sequence repeat markers (eSSRs) from de novo transcriptome sequencing. We tested a set of 17 eSSRs on a collection of C. virginianum genomic DNA samples from the three botanical varieties, and a new putative type observed in Tennessee, dubbed ''Ocoee-type'' for its geographic origin. The polymerase chain reaction and capillary electrophoresis analyses with downstream population genetics tools verified the usefulness of the eSSRs. By applying this approach, we showed recognizable variation within Chrysogonum, although it did not correspond exactly to previous infraspecific classifications. Finally, as demonstrated for the commercial cultivar Pierre included in the study, the eSSRs can be used for enhancing the future breeding or hybridization efforts of this ornamental plant.