The 141-year period for Dr. Beal's seed viability experiment: A hybrid surprise

Premise

In 1879, Dr. William Beal buried 20 glass bottles filled with seeds and sand at a single site at Michigan State University. The goal of the experiment was to understand seed longevity in the soil, a topic of general importance in ecology, restoration, conservation, and agriculture, by periodically assaying germinability of these seeds over 100 years. The interval between germination assays has been extended and the experiment will now end after 221 years, in 2100.

Methods

We dug up the 16th bottle in April 2021 and attempted to germinate the 141-year-old seeds it contained. We grew germinants to maturity and identified these to species by vegetative and reproductive phenotypes. For the first time in the history of this experiment, genomic DNA was sequenced to confirm species identities.

Results

Twenty seeds germinated over the 244-day assay. Eight germinated in the first 11 days. All 20 belonged to the Verbascum genus: Nineteen were V. blattaria according to phenotype and ITS2 genotype; and one had a hybrid V. blattaria × V. thapsus phenotype and ITS2 genotype. In total, 20/50 (40%) of the original Verbascum seeds in the bottle germinated in year 141.

Conclusions

While most species in the Beal experiment lost all seed viability in the first 60 years, a high percentage of Verbascum seeds can still germinate after 141 years in the soil. Long-term experiments such as this one are rare and invaluable for studying seed viability in natural soil conditions.     

Florivores decrease pollinator visitation in a self-incompatible plant

Different biotic interactions may influence one another to produce complex patterns of direct and indirect effects, which together influence plant reproductive success. However, so far most studies on plant-animal interactions have focused on single interactions in isolation. In this study, we studied the effect of florivory by the weevil Cionus nigritarsis on pollinator visitation rate in the self-incompatible perennial herb Verbascum nigrum by combining observations of florivory and pollination in natural populations with records of pollinator visitation to plants with different levels of experimentally inflicted damage.Increasing levels of damage through either natural or simulated florivory resulted in fewer pollinator visits per plant and per flower. As expected, the magnitude of the indirect effect of florivory on pollinator visitation was proportional to the intensity of florivory. Our results indicate that biotic non-pollinating agents, such as florivores, may induce substantial changes in pollinator availability. Therefore, studies addressing different plant-animal interactions in parallel are necessary to better comprehend the factors influencing the reproductive performance and demography of flowering plants.     

Simultaneous determination of flavonoids and phenylethanoids in the flowers of Verbascum densiflorum and V. phlomoides by high‐performance liquid chromatography

Introduction – Mullein (Verbascum) flowers are highly valued herbal drugs used in the treatment of inflammation, asthma, spasmodic coughs and other respiratory tract diseases. Their phenolic constituents are considered to be responsible for the anti‐inflammatory and antimicrobial activity of the herb. However, knowledge about the contents of phenolics in flowers is limited and no HPLC method for their analysis is available. Objective – To develop and validate an RP‐HPLC‐UV method for the simultaneous determination of eight flavonoids and two phenylethanoids in the flowers of Verbascum densiflorum and V. phlomoides. Methodology – HPLC separation was accomplished on a C₁₈ Lichrosphere 100 column (5 µm, 250 mm × 4.6 mm, i.d.) with an acetonitrile gradient elution using aqueous 0.5% (w/v) orthophosphoric acid solution containing 1% (v/v) tetrahydrofurane. Results – All the calibration curves showed good linear correlation coefficients (r > 0.997) over the wide test ranges. The relative standard deviation of the method was less than 3.4% for intra‐ and inter‐day assays, and the average recoveries were between 93.5 and 101.9%. High sensitivity was demonstrated with detection limits of 0.062–0.083 µg/mL for flavonoid aglycones, 0.156–0.336 µg/mL for flavonoid glycosides and 0.390–0.555 µg/mL for phenylethanoids. The flower samples of V. phlomoides were found to contain high levels of diosmin and tamarixetin 7‐rutinoside (2.327–2.392% of dry weight), whereas verbascoside (0.688–0.742% of dry weight) and luteolin 7‐glucoside (0.204–0.279% of dry weight) dominated in the V. densiflorum flower. Conclusion – The HPLC method established is appropriate for the quality assurance and the differentiation of V. phlomoides and V. densiflorum samples. Copyright © 2009 John Wiley & Sons, Ltd.     

Low Diversity and Divergence in the fil1 Gene Family of Antirrhinum (Scrophulariaceae)

Detailed nucleotide diversity studies revealed that the fil1 gene of Antirrhinum, which has been reported to be single copy, is a member of a gene family composed of at least five genes. In four Antirrhinum majus populations with different mating systems and one A. graniticum population, diversity within populations is very low. Divergence among Antirrhinum species and between Antirrhinum and Digitalis is also low. For three of these genes we also obtained sequences from a more divergent member of the Scrophulariaceae, Verbascum nigrum. Compared with Antirrhinum, little divergence is again observed. These results, together with similar data obtained previously for five cycloidea genes, suggest either that these gene families (or the Antirrhinum genome) are unusually constrained or that there is a low rate of substitution in these lineages. Using a sample of 52 genes, based on two measures of codon usage (ENC and GC3 content), we show that cyc and fil1 are among the least biased Antirrhinum genes, so that their low diversity is not due to extreme codon bias. Received: 20 June 2000 / Accepted: 25 October 2000     

The effect of solar UV radiation on four plant species occurring in a coastal grassland vegetation in The Netherlands

During the summer of 1992, growth and some physiological parameters of four native plant species occurring in a coastal grassland in The Netherlands, were studied after reduction of solar UV irradiance using different cut-off filters. Biomass production, morphology and photosynthesis of all species tested were unaffected by the different treatments. Litter production of Plantago lanceolata was increased in the absence of the total UV waveband, indicating a possible role for this waveband in plant senescence. Depletion of the total UV waveband from sunlight resulted in alterations in biomass allocation in Calamagrostis epigeios and Urtica dioica while no changes were observed in P. Ianceolata and Verbascum thapsus. In C. epigeios an increase in the specific leaf area was observed, whereas in U. dioica root weight per total plant weight was decreased resulting in an increase in the shoot/root ratio. Both photosynthetic and UV-absorbing pigment concentrations were altered by the different filter applications. When compared to control plants receiving full sunlight, depletion of UV-B resulted in a significant increase in chlorophyll concentration in U. dioica leaves, this however did not affect photosynthetic rate. The presence of UV-B radiation enhanced the UV-absorbance of leaf extracts of all species except P. lanceolata. Optical characteristics of the leaves were also changed. Both the quantity ( P. lanceolata and U. dioica ) and the quality (all species) of radiation transmitted by the leaves was affected by the different treatments.