The genome of the vining fern Lygodium microphyllum highlights genomic and functional differences between life phases of an invasive plant
Authors: Pelosi, J., Davenport, R., Kuo, L.-Y., Gray, L. N., Dant, A. J., Kim, E. H., Li, F.-W., Dlugosch, K. M., Krabbenhoft, T. J., Barbazuk, W. B., Sessa, E. B.
The study presents a chromosome-level reference genome for the invasive fern Lygodium microphyllum and compares the transcriptomic and epigenomic profiles of its haploid gametophyte and diploid sporophyte phases, revealing differential regulation of developmental genes and similar methylation patterns across tissues. Base‑pair resolution methylome data and freezing‑stress experiments show that each life phase employs distinct molecular pathways for stress response, emphasizing the importance of considering both phases in invasive‑species management.
The study investigates the Arabidopsis ribosomal protein RPS6A and its role in auxin‑related root growth, revealing that rps6a mutants display shortened primary roots, fewer lateral roots, and defective vasculature that are not rescued by exogenous auxin. Cell biological observations and global transcriptome profiling show weakened auxin signaling and reduced levels of PIN auxin transporters in the mutant, indicating a non‑canonical function of the ribosomal subunit in auxin pathways.
The study generated a high-quality genome assembly for Victoria cruziana and used comparative transcriptomics to identify anthocyanin biosynthesis genes and their transcriptional regulators that are differentially expressed between white and light pinkish flower stages. Differential expression of structural genes (VcrF3H, VcrF35H, VcrDFR, VcrANS, VcrarGST) and transcription factors (VcrMYB123, VcrMYB-SG6_a, VcrMYB-SG6_b, VcrTT8, VcrTTG1) correlates with the observed flower color change.
The study investigates how miR394 influences flowering time in Arabidopsis thaliana by combining transcriptomic profiling of mir394a mir394b double mutants with histological analysis of reporter lines. Bioinformatic analysis identified a novel lncRNA overlapping MIR394B (named MIRAST), and differential promoter activity of MIR394A and MIR394B suggests miR394 fine‑tunes flower development through transcription factor and chromatin remodeler regulation.
The study demonstrates that RNA extracted from herbarium specimens can be used to generate high‑quality transcriptomes, comparable to those from fresh or silica‑dried samples. By assembling and comparing transcriptomes across specimen types, the authors validated a plant immune receptor synthesized from a 1956 collection, proving archival RNA’s utility for functional genomics. These findings challenge the prevailing view that herbarium RNA is unsuitable for transcriptomic analyses.
The study profiled the Arabidopsis apoplastic proteome during pattern‑triggered immunity induced by the flg22 peptide, using apoplastic washing fluid with minimal cytoplasmic contamination followed by LC‑MS/MS. Results showed consistent PTI‑specific enrichment and depletion of peptides, a bias toward ectodomain peptides of receptor‑like kinases, and increased abundance of the exosome marker tetraspanin 8, indicating heightened exosome levels during PTI.