An extensive survey of genome sizes and ploidy levels was conducted for a diverse collection of Berberis and Mahonia taxa (Berberidaceae). Propidium iodide flow cytometric analysis was conducted using Pisum sativum L. ‘Ctirad’ (2C DNA = 8.76 pg) as an internal standard to determine genome sizes. Mean 1CX genome sizes varied between the two Mahonia subgenera (Occidentales = 1.17 ± 0.02, Orientales = 1.27 ± 0.01), whereas those of Berberis subgenera were similar (Australes = 1.45 ± 0.03, Septentrionales = 1.47 ± 0.02) and each significantly larger than those of Mahonia. Traditional cytology was performed on representative species to calibrate genome sizes with ploidy levels. Polyploidy among both wild and cultivated taxa was found to be rare. Although the majority of species were determined to be diploid with 2n = 2x = 28, artificially induced autopolyploid Berberis thunbergii seedlings were confirmed to be tetraploid and an accession of Mahonia nervosa was confirmed to be hexaploid. Genome size and ploidy level reports for the majority of taxa sampled are presented for the first time and are intended to be of use to plant breeders, ecologists, and systematists.

Miscanthus sinensis Andersson is a popular ornamental grass and has additional potential as a bioenergy crop. In some regards, the ability of M. sinensis to withstand a broad range of climatic and cultural conditions is desirable, but its propensity to rapidly colonize open and disturbed environments has allowed it to naturalize and become weedy in some regions in the United States. Considering the value of this crop, the development and documentation of infertile clones would be desirable. Triploid plants were evaluated for male and female fertility using pollen viability staining and seed set and germination, respectively. Pollen viability staining, seed set, and seed germination from triploid plants were reduced compared with diploids but varied considerably within each cytotype. Overall, relative female fertility of individual triploids clones [(% seed set × % germination for triploid)/(% seed set × % germination for diploid control)] was reduced substantially and ranged from 49% to 0.7%. Additionally, the reproductive pathways of triploid plants were examined by evaluating the 2C genome sizes of progeny derived from open pollination. The limited progeny arising from open-pollinated triploids were predominantly aneuploids with 2C genome sizes intermediate between diploids and triploids. There was no clear evidence of apomixis, selfing, or triploid × triploid fertilization events observed among triploid parents. Formation of unreduced gametes was rare for both ploidy levels (≈1%). The considerable reduction in female fertility in some triploid clones combined with the limited production of primarily aneuploid progeny provides highly infertile alternatives to existing diploid cultivars.

The invasive liana Euonymus fortunei (Turcz.) Hand.-Maz. (wintercreeper) is an emerging invader that through monodominance of woodlands can drastically reduce native species diversity and alter nutrient cycling. We studied how the vegetation and soils of invaded (INV), “native” (NAT), and wintercreeper removal (REM) site treatments influenced seed germination and seedling survival of this invader. The effect of aril (with vs. without) was also tested for wintercreeper seeds under field and in vitro conditions as a proxy for gravity vs. animal dispersal of seed, respectively. Germination was significantly delayed for seeds sown with an aril (vs. without), as well as those sown in INV soils (vs. NAT or REM), but neither site nor aril affected total germination. The proportion of germinated seedlings that survived after the first winter was significantly different based on site (p = 0.054) and aril (p = 0.071) treatments, with lower survival resulting from seeds sown without arils, and for seeds sown in INV sites. Magnesium (Mg) concentrations were significantly higher among INV soils (vs. NAT) and provide further support that wintercreeper is a driver of soil nutrient change. Our findings that aril-enclosed (gravity-dispersed) seeds yielded greater survival, despite being locally dispersed within invaded sites (where survival was lowest), support the historically slow rate of spread for this species.

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