Whole-genome sequencing reveals the molecular basis of sex determination in the dioecious wild yam Dioscorea tokoro
Authors: Kudoh, A., Natsume, S., Sugihara, Y., Kato, H., Abe, A., Oikawa, K., Shimizu, M., Itoh, K., Tsujimura, M., Takano, Y., Sakai, T., Adachi, H., Ohta, A., Ohtsu, M., Ishizaki, T., Terachi, T., Terauchi, R.
The study reveals that the dioecious monocot Dioscorea tokoro employs a male heterogametic (XY) sex-determination system with sex-determining regions on chromosome 3, including X- and Y-specific pericentromeric regions. Two Y-specific candidate genes, BLH9 (a homeobox protein) and HSP90 (a molecular chaperone), are identified as likely mediators of female organ suppression and pollen development, respectively, providing insight into the evolution of dioecy in plants.
The study used comparative transcriptomics across Erysimum species to identify two 2‑oxoglutarate‑dependent dioxygenases, CARD5 and CARD6, responsible for the 14β‑ and 21‑hydroxylation steps in cardenolide biosynthesis in Erysimum cheiranthoides. Knockout mutants lacking these genes accumulated pathway intermediates, and transient expression in Nicotiana benthamiana confirmed their enzymatic functions, while structural modeling pinpointed residues linked to neofunctionalization.
Comparative transcriptomics uncovers plant and fungal genetic determinants of mycorrhizal compatibility
Authors: Marques-Galvez, J. E., de Freitas Pereira, M., Nehls, U., Ruytinx, J., Barry, K., Peter, M., Martin, F., Grigoriev, I. V., Veneault-Fourrey, C., Kohler, A.
The study used comparative and de‑novo transcriptomic analyses in poplar to uncover plant and fungal gene regulons that govern ectomycorrhizal (ECM) compatibility, distinguishing general fungal‑sensing responses from ECM‑specific pathways. Key findings include modulation of jasmonic acid‑related defenses, coordinated regulation of secretory and cell‑wall remodeling genes, and dynamic expression of the Common Symbiosis Pathway during early and mature symbiosis stages.
The study generated high‑quality genome assemblies for 12 indica and japonica rice accessions and demonstrated that structural variants (SVs) are abundant and strongly associated with heterosis across 17 agronomic traits. Correlation analyses revealed that SV count between parental lines predicts hybrid performance, and functional validation of SVs in S5‑ORF5 and OsBZR1 confirmed their contributions to seed setting rate and yield heterosis, supporting an overdominance model for inter‑subspecific hybrid vigor.
High radiosensitivity in the conifer Norway spruce (Picea abies) due to lesscomprehensive mobilisation of protection and repair responses compared to the radiotolerant Arabidopsis thaliana
Authors: Bhattacharjee, P., Blagojevic, D., Lee, Y., Gillard, G. B., Gronvold, L., Hvidsten, T. R., Sandve, S. R., Lind, O. C., Salbu, B., Brede, D. A., Olsen, J. E.
The study compared early protective, repair, and stress responses to chronic gamma irradiation in the radiosensitive conifer Norway spruce (Picea abies) and the radiotolerant Arabidopsis thaliana. Norway spruce exhibited growth inhibition, mitochondrial damage, and higher DNA damage at low dose rates, while Arabidopsis maintained growth, showed minimal organelle damage, and activated DNA repair and antioxidant genes even at the lowest dose rates. Transcriptomic analysis revealed that the tolerant species mounts a robust transcriptional response at low doses, whereas the sensitive species only responds at much higher doses.
Four isolates of Pythium aphanidermatum obtained from infected amaranth seedlings were confirmed by morphology and ITS rDNA sequencing and shown to cause severe root loss and damping‑off in both plate and soil assays, with up to 100% disease incidence in susceptible genotypes. The genome of isolate PT2-1-1 was sequenced, revealing a 51.55 Mb assembly with 14,453 protein‑coding genes, including numerous plant cell wall‑degrading enzymes and candidate intracellular and apoplastic effectors such as Crinkler and YxSL[RK] proteins. This second genome assembly and the demonstrated pathogenic variation provide a foundation for studying host‑pathogen interactions in amaranth.
The study used comparative transcriptomics to examine how Fusarium oxysporum isolates with different lifestyles on angiosperms regulate effector genes during infection of the non‑vascular liverwort Marchantia polymorpha. Core effector genes on fast core chromosomes are actively expressed in the bryophyte host, while lineage‑specific effectors linked to angiosperm pathogenicity are silent, and disruption of a compatibility‑associated core effector alters the expression of other core effectors, highlighting conserved fungal gene networks across plant lineages.
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 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.