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The large size and complexity of most fern genomes have hampered efforts to elucidate fundamental aspects of fern biology and land plant evolution through genome-enabled research. Here we present a chromosomal genome assembly and associated methylome, transcriptome and metabolome analyses for the model fern species Ceratopteris richardii. The assembly reveals a history of remarkably dynamic genome evolution including rapid changes in genome content and structure following the most recent whole-genome duplication approximately 60 million years ago. These changes include massive gene loss, rampant tandem duplications and multiple horizontal gene transfers from bacteria, contributing to the diversification of defence-related gene families. The insertion of transposable elements into introns has led to the large size of the Ceratopteris genome and to exceptionally long genes relative to other plants. Gene family analyses indicate that genes directing seed development were co-opted from those controlling the development of fern sporangia, providing insights into seed plant evolution. Our findings and annotated genome assembly extend the utility of Ceratopteris as a model for investigating and teaching plant biology.

Ferns are the only major lineage of vascular plants not represented by a sequenced nuclear genome. This lack of genome sequence information significantly impedes our ability to understand and reconstruct genome evolution not only in ferns, but across all land plants. Azolla and Ceratopteris are ideal and complementary candidates to be the first ferns to have their nuclear genomes sequenced. They differ dramatically in genome size, life history, and habit, and thus represent the immense diversity of extant ferns. Together, this pair of genomes will facilitate myriad large-scale comparative analyses across ferns and all land plants. Here we review the unique biological characteristics of ferns and describe a number of outstanding questions in plant biology that will benefit from the addition of ferns to the set of taxa with sequenced nuclear genomes. We explain why the fern clade is pivotal for understanding genome evolution across land plants, and we provide a rationale for how knowledge of fern genomes will enable progress in research beyond the ferns themselves.

Ferns are the only major lineage of vascular plants not represented by a sequenced nuclear genome. This lack of genome sequence information significantly impedes our ability to understand and reconstruct genome evolution not only in ferns, but across all land plants. Azolla and Ceratopteris are ideal and complementary candidates to be the first ferns to have their nuclear genomes sequenced. They differ dramatically in genome size, life history, and habit, and thus represent the immense diversity of extant ferns. Together, this pair of genomes will facilitate myriad large-scale comparative analyses across ferns and all land plants. Here we review the unique biological characteristics of ferns and describe a number of outstanding questions in plant biology that will benefit from the addition of ferns to the set of taxa with sequenced nuclear genomes. We explain why the fern clade is pivotal for understanding genome evolution across land plants, and we provide a rationale for how knowledge of fern genomes will enable progress in research beyond the ferns themselves.

SUMMARY: The anther‐enriched phased, small interfering RNAs (phasiRNAs) play vital roles in sustaining male fertility in grass species. Their long non‐coding precursors are synthesized by RNA polymerase II and are likely regulated by transcription factors (TFs). A few putative transcriptional regulators of the 21‐ or 24‐nucleotide phasiRNA loci (referred to as 21‐ or 24‐PHAS loci) have been identified in maize (Zea mays), but whether any of the individual TFs or TF combinations suffice to activate any PHAS locus is unclear. Here, we identified the temporal gene coexpression networks (modules) associated with maize anther development, including two modules highly enriched for the 21‐ or 24‐PHAS loci. Comparisons of these coexpression modules and gene sets dysregulated in several reported male sterile TF mutants provided insights into TF timing with regard to phasiRNA biogenesis, including antagonistic roles for OUTER CELL LAYER4 and MALE STERILE23. Trans‐activation assays in maize protoplasts of individual TFs using bulk‐protoplast RNA‐sequencing showed that two of the TFs coexpressed with 21‐PHAS loci could activate several 21‐nucleotide phasiRNA pathway genes but not transcription of 21‐PHAS loci. Screens for combinatorial activities of these TFs and, separately, the recently reported putative transcriptional regulators of 24‐PHAS loci using single‐cell (protoplast) RNA‐sequencing, did not detect reproducible activation of either 21‐PHAS or 24‐PHAS loci. Collectively, our results suggest that the endogenous transcriptional machineries and/or chromatin states in the anthers are necessary to activate reproductive PHAS loci. Significance Statement: This work identifies the temporal gene coexpression networks associated with maize anther development, including two modules highly enriched for the 21‐ or 24‐nucleotide reproductive phased, small interfering RNA (phasiRNA) loci. Trans‐activation assays of putative transcriptional regulators of the phasiRNA loci using bulk and single‐cell RNA‐sequencing suggest that endogenous transcriptional machineries and/or chromatin states in the anthers are necessary to activate reproductive phasiRNA loci. [ABSTRACT FROM AUTHOR]

Running is a popular and convenient form of leisure-time physical activity, with participation levels increasing in the United Kingdom in low physical activity groups such as women and overweight individuals, following the introduction of schemes such as Couch to 5km (C25 K). However, despite the popularity of these programmes, there is little research into the social and psychological processes involved in effective engagement and long-term behaviour changes. Therefore, the aim of the study was to explore the impact of participation in a 10-week group-led beginners running programme on participant motivation, attendance and well-being using Self-Determination Theory (STD) as a theoretical framework. Participants (N = 124; Mage = 40.74) were recruited from a beginners' running programme based in the North West of England and self-completed questionnaires during weeks 2, 6 and 10. Future intentions to run were also assessed at 3- and 6-month follow up. Results demonstrated the positive impact an adapted C25 K model can have upon elements of self-perceptions (particularly perceived competence) and future intentions to run. The path analysis, which looked at average values over time, demonstrated that leader autonomy support positively impacted upon participants' basic needs satisfaction, which led to the development of more self-determined motivation, and in turn led to higher levels of attendance and mental well-being. Critically for drop-out, results from multiple regression analysis indicated that individuals with a higher BMI rated leader autonomy support as lower and felt less competent during the programme. A number of research and practical recommendations are discussed. [ABSTRACT FROM AUTHOR]