Gamete sex and elevation affect genetically based variation for unreduced gamete production in a mixed-ploidy plant.

Premise: Unreduced gametes are the primary mechanism of neopolyploid formation. Their production in diploid populations is arguably maladaptive, but the magnitude and patterns of genetically based variation maintained in natural populations are poorly understood.

Methods: We examined variation in male and female unreduced gamete production among plants from different elevations in fireweed, Chamerion angustifolium, grown in a common environment.

Demographic and reproductive impacts of hybridization unrelated to hybrid viability in a native plant.

Premise: Introduced species can influence native congeners through production of hybrids and introgression, but impacts not involving viable hybrids, such as reduced conspecific offspring and increased asexual seed production, are rarely examined. Here we tested for these demographic and reproductive consequences of hybridization between introduced, domesticated apple (Malus domestica) and native crabapple (M. coronaria) in southern Canada.

Predictive Molecular Design and Structure-Property Validation of Novel Terpene-Based, Sustainably Sourced Bacterial Biofilm-Resistant Materials.

Presented in this work is the use of a molecular descriptor, termed the α parameter, to aid in the design of a series of novel, terpene-based, and sustainable polymers that were resistant to biofilm formation by the model bacterial pathogen . To achieve this, the potential of a range of recently reported, terpene-derived monomers to deliver biofilm resistance when polymerized was both predicted and ranked by the application of the α parameter to key features in their molecular structures. These monomers were derived from commercially available terpenes (, α-pinene, β-pinene, and carvone), and the prediction of the biofilm resistance properties of the resultant novel (meth)acrylate polymers was confirmed using a combination of high-throughput polymerization screening (in a microarray format) and testing.

Polyploidy increases storage but decreases structural stability in Arabidopsis thaliana.

Whole-genome duplication, leading to polyploidy and endopolyploidy, is widespread throughout the tree of life. Both polyploidy and endopolyploidy can increase cell size via nucleotypic effects, but the phenotypic consequences of increased cell size at the tissue and whole-organism levels are less well understood. We quantified the consequences of autopolyploidy and endopolyploidy in nine diploid accessions of Arabidopsis thaliana, representing a gradient in endopolyploidy, to their corresponding experimentally synthesized neo-tetraploid and neo-octoploid cytotypes.

Outbreak Associated with Pasteurized Milk.

In July 2019, we investigated a cluster of cases affecting a youth summer camp and nearby community in northeastern Pennsylvania. After initial telephone interviews with camp owners and community members, we identified pasteurized milk from a small dairy conducting on-site pasteurization, Dairy A, as a shared exposure. We conducted site visits at the camp and Dairy A where we collected milk and other samples.

Endopolyploidy is associated with leaf functional traits and climate variation in Arabidopsis thaliana.

Premise: Endopolyploidy is widespread throughout the tree of life and is especially prevalent in herbaceous angiosperms. Its prevalence in this clade suggests that endopolyploidy may be adaptive, but its functional roles are poorly understood. To address this gap in knowledge, we explored whether endopolyploidy was associated with climatic factors and correlated with phenotypic traits related to growth.

Corrigendum: Different Patterns of Ecological Divergence Between Two Tetraploids and Their Diploid Counterpart in a Parapatric Linear Coastal Distribution Polyploid Complex.

[This corrects the article DOI: 10.3389/fpls.2020.

The role of multiple reproductive barriers: strong post-pollination interactions govern cytotype isolation in a tetraploid-octoploid contact zone.

Background And Aims: Polyploidy is an important contributor to sympatric speciation and assortative mating is a key mechanism driving cytotype interactions in contact zones. While strong reproductive barriers can mediate the coexistence of different cytotypes in sympatry, positive frequency-dependent mating disadvantage ultimately drives the transition to single-ploidy populations. However, comprehensive estimates of reproductive isolation among cytotypes and across multiple barriers are rare.

Different Patterns of Ecological Divergence Between Two Tetraploids and Their Diploid Counterpart in a Parapatric Linear Coastal Distribution Polyploid Complex.

Polyploidization is a widespread mechanism of evolutionary divergence in flowering plants. Ecological divergence of polyploid lineages has been proposed as a key process shaping the distribution of cytotypes in nature (niche shift hypothesis); however, evidence for the role of niche separation in replicated diploid-polyploid species pairs is still needed. This study aimed to assess the role of abiotic factors shaping current cytotype distributions.

The influence of experimentally induced polyploidy on the relationships between endopolyploidy and plant function in .

Whole genome duplication, leading to polyploidy and endopolyploidy, occurs in all domains and kingdoms and is especially prevalent in vascular plants. Both polyploidy and endopolyploidy increase cell size, but it is unclear whether both processes have similar effects on plant morphology and function, or whether polyploidy influences the magnitude of endopolyploidy. To address these gaps in knowledge, fifty-five geographically separated diploid accessions of that span a gradient of endopolyploidy were experimentally manipulated to induce polyploidy.

The origins and evolutionary history of feral apples in southern Canada.

Feral populations of domesticated crops can establish through two nonmutually exclusive pathways: hybridization with native relatives and recruitment of and recombination between known cultivars. The extent and relative importance of these pathways is not known, especially for woody fruit crops. Here, we examined the evolutionary origins of feral populations of Malus domestica (domestic apple) in southern Canada using a population genetic analysis.

Evolutionary associations between polyploidy, clonal reproduction, and perenniality in the angiosperms.

Clonal reproduction is thought to facilitate polyploid establishment in the angiosperms, but the evolutionary relationship between polyploidy and clonality has not been thoroughly tested. A perennial life history may confer many of the same advantages, and the relative importance of clonality versus perenniality is unknown. We used phylogenetic comparative analyses of 1751 species to examine associations between polyploidy, clonality, and life history.

Whole-genome duplication decreases clonal stolon production and genet size in the wild strawberry Fragaria vesca.

Premise Of The Study: Clonal reproduction is often associated with polyploidy and is expected to influence polyploid establishment success, but the immediate effects of whole-genome duplication (WGD) on clonal reproduction in autopolyploids are unknown.

Methods: We used synthesized neopolyploids to assess the direct effects of WGD on stolon and plantlet production in the wild strawberry Fragaria vesca by (1) comparing absolute clonal investment between diploids and neotetraploids under high and low resource conditions in the greenhouse and (2) determining realized clonal plantlet establishment and genet spatial structure using artificial field populations comprising both cytotypes.

Key Results: Neotetraploids produced fewer stolons and plantlets than diploids at slower weekly rates in the greenhouse when resources were high, resulting in lower total investment in clonal reproduction.

Immediate vs. evolutionary consequences of polyploidy on clonal reproduction in an autopolyploid plant.

Background And Aims: Clonal reproduction in polyploids is expected to exceed that in diploids, due to either the immediate direct effects of whole-genome duplication (WGD) or selection during establishment. The timing of polyploidy effects on clonality are largely unknown despite its hypothesized influence on polyploid success. This study tests the direction and timing of divergence in clonal traits in diploid and polyploid Chamerion angustifolium.

Complex cytogeographical patterns reveal a dynamic tetraploid-octoploid contact zone.

The distribution of cytotypes in mixed-ploidy species is crucial for evaluating ecological processes involved in the establishment and evolution of polyploid taxa. Here, we use flow cytometry and chromosome counts to explore cytotype diversity and distributions within a tetraploid-octoploid contact zone. We then use niche modelling and ploidy seed screening to assess the roles of niche differentiation among cytotypes and reproductive interactions, respectively, in promoting cytotype coexistence.

Mixed-Ploidy Species: Progress and Opportunities in Polyploid Research.

Mixed-ploidy species harbor a unique form of genomic and phenotypic variation that influences ecological interactions, facilitates genetic divergence, and offers insights into the mechanisms of polyploid evolution. However, there have been few attempts to synthesize this literature. We review here research on the cytotype distribution, diversity, and dynamics of intensively studied mixed-ploidy species and consider the implications for understanding mechanisms of polyploidization such as cytotype formation, establishment, coexistence, and post-polyploid divergence.

Evolutionary Dynamics of Unreduced Gametes.

Unreduced gametes, which have the somatic (2n) chromosome number, are an important precursor to polyploid formation and apomixis. The product of irregularities in meiosis, 2n gametes are expected to be rare and deleterious in most natural populations, contrary to their wide taxonomic distribution and the prevalence of polyploidy. To better understand this discrepancy, we review contemporary evidence related to four aspects of 2n gamete dynamics in natural populations: (i) estimates of their frequency; (ii) their environmental and genetic determinants; (iii) adaptive and nonadaptive processes regulating their evolution; and (iv) factors regulating their union and production of polyploids in diploid populations.

Frequency and maintenance of unreduced gametes in natural plant populations: associations with reproductive mode, life history and genome size.

Fertilization involving unreduced (2n) gametes is considered the dominant mechanism of polyploid formation in angiosperms; however, our knowledge of the prevalence of and evolutionary mechanisms maintaining 2n gametes in natural populations is limited. We hypothesize that 2n gametes are deleterious consequences of meiotic errors maintained by mutation-selection balance and should increase in species with relaxed opportunities for selection on sexual processes (asexuality), reduced efficacy of selection (asexuality, selfing) and increased genome instability (high chromosome number). We used flow cytometry to estimate male 2n gamete production in 60 populations from 24 species of Brassicaceae.

Genetic and environmental determinants of unreduced gamete production in Brassica napus, Sinapis arvensis and their hybrids.

Unreduced gametes, sperm or egg cells with the somatic chromosome number, are an important mechanism of polyploid formation and gene flow between heteroploid plants. The meiotic processes leading to unreduced gamete formation are well documented, but the relative influence of environmental and genetic factors on the frequency of unreduced gametes remain largely untested. Furthermore, direct estimates of unreduced gametes based on DNA content are technically challenging and, hence, uncommon.

Effect of inbreeding on pollen tube growth in diploid and tetraploid Chamerion angustifolium: Do polyploids mask mutational load in pollen?

Premise Of The Study: Deleterious recessive mutations are an important determinant of fitness (mutational load) in the sporophytic phase of plants and a major cause of inbreeding depression; however, their role in gametophyte function is less well documented but may account for variation in pollen tube growth and siring ability, especially between diploid and polyploid plants, which can mask the load.

Methods: We investigated the role of mutational load in pollen performance using the perennial polyploid Chamerion angustifolium by comparing tube growth of pollen, in styles and in growth medium, from inbred (selfed) and outbred diploids to that of inbred and outbred tetraploids. Pollen from tetraploids is expected to mask deleterious mutations more effectively in the outbred condition but reveal them after inbreeding.

Distinguishing 2N gamete nuclei from doublets in pollen using flow cytometry and pulse analysis.

The value of flow cytometry for quantifying unreduced (2N) pollen production in plants is well recognized; however, the approach has been limited by technical obstacles to obtaining high quality nuclei fluorescence histograms and the difficulty in distinguishing 2N nuclei from 1N doublets. Here, we use mathematical arguments and observations of fluorescence properties of angiosperm pollen nuclei to generate guidelines for applying pulse analysis to correct for doublets in pollen nuclei data. We show that the theoretical requirements for applying pulse analysis for doublet correction are met when nucleus fluorescence height and/or width measures in the unreduced gamete (2C DNA content) region exhibit bimodality (reflecting singlets and doublets) in combination with unimodal distributions of the same parameters in the reduced gamete (1C) region.