A moss N-Acetyltransferase-MAPK protein controls 2D to 3D developmental transition via acetylation and phosphorylation changes
Authors: de Luxan Hernandez, C., Ammitsoe, T. J., Kanne, J. V., Stanimirovic, S., Roux, M., Weeks, Z., Schutzbier, M., Dürnberger, G., Roitinger, E., Zhang, L., Spadiut, O., Ishikawa, M., Hasebe, M., Moody, L., Dagdas, Y., Rodriguez, E., Petersen, M.
The study identifies a moss‑specific fusion protein, Rosetta NATD‑MAPK 1 (RAK1), that combines a MAPK domain with an N‑acetyltransferase and demonstrates that its acetyltransferase activity is enhanced upon MAPK activation. Knockout of RAK1 impairs the 2D‑to‑3D developmental transition in Physcomitrium patens, and mass‑spectrometry reveals associated changes in acetylation and phosphorylation linked to metabolic reprogramming.
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.
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.
The study reveals that a conserved serine adjacent to the catalytic glutamate in TIR domains is essential for NAD+‑cleaving activity, and that phosphorylation of this serine by plant calcium‑dependent protein kinases (CPKs) or mammalian kinases (CAMK2D, TBK1) inhibits the activity, thereby preventing growth repression and cell death. This phosphorylation-based mechanism provides a universal means to balance growth and immune defense across species.
The study identifies RAF24, a B4 Raf-like MAPKKK, as a novel regulator of flowering time in Arabidopsis, demonstrating that RAF24 controls the phosphorylation of the ubiquitin ligase HUB2 via SnRK2 kinases, thereby modulating H2Bub1 levels. Phospho‑mimetic and phospho‑ablative HUB2 mutants confirm that phosphorylation at S314 is critical for proper flowering timing.
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 uncovers a feedback mechanism wherein phosphomimic mutation (PetD T4E) or deletion of the N‑terminal five amino acids of the b6f subunit PetD suppresses STT7 kinase activity, leading to a State 1‑locked phenotype and impaired electron transfer, highlighting the essential regulatory role of the PetD N‑terminus in photosynthetic state transitions.
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.