A SABATH family enzyme regulates development via the gibberellin-related pathway in the liverwort Marchantia polymorpha
Authors: Kawamura, S., Shimokawa, E., Ito, M., Nakamura, I., Kanazawa, T., Iwano, M., Sun, R., Yoshitake, Y., Yamaoka, S., Yamaguchi, S., Ueda, T., Kato, M., Kohchi, T.
The study identified 12 SABATH methyltransferase genes in the liverwort Marchantia polymorpha and demonstrated that MpSABATH2 is crucial for normal thallus growth and gemma cup formation. Loss‑of‑function mutants displayed developmental phenotypes reminiscent of far‑red light responses, which were linked to gibberellin metabolism and could be partially rescued by inhibiting GA biosynthesis or supplying the GA precursor ent‑kaurenoic acid. These findings suggest that SABATH enzymes independently evolved regulatory roles in land‑plant development.
The study establishes a tractable system using the large bloom-forming diatom Coscinodiscus granii and its natural oomycete parasite Lagenisma coscinodisci, enabling manual isolation of single host cells and stable co-cultures. High‑quality transcriptomes for both partners were assembled, revealing diverse oomycete effectors and a host transcriptional response involving proteases and exosome pathways, while also profiling the co‑occurring heterotrophic flagellate Pteridomonas sp. This tripartite platform provides a unique marine model for dissecting molecular mechanisms of oomycete‑diatom interactions.
The study demonstrates that carbon availability promotes gemma cup formation in Marchantia polymorpha by activating cytokinin signaling, which up‑regulates the transcription factors MpGCAM1 and MpSTG. Pharmacological and genetic manipulations showed that cytokinin accumulation in response to sucrose and high light is sufficient to overcome low‑sucrose repression, and that this pathway operates independently of KAI2A‑MAX2 mediated karrikin signaling. The findings suggest a conserved carbon‑cytokinin interaction governing developmental plasticity across land plants.
The study used Weighted Gene Correlation Network Analysis (WGCNA) and GENIE3 to construct co‑expression modules and gene regulatory networks (GRNs) in barley subjected to Fusarium head blight and drought stress. Integration of these approaches highlighted overlapping regulatory patterns, pinpointing WRKY transcription factors as central to FHB response, while bHLH and NAC family members showed stress‑specific roles. Promoter motif enrichment further validated predicted TF‑target interactions, offering candidate regulators for future functional validation.
The authors used computational simulations of plant cellular metabolism under historical atmospheric conditions to demonstrate that reduced CO₂ and increased aridity can drive the evolutionary transition from C₃ to CAM photosynthesis. Their results suggest that while future elevated CO₂ may favor a reversion to C₃-like behavior, drought consistently promotes CAM regardless of CO₂ or temperature, and a minimum O₂ level is required for nocturnal respiration in CAM.
The study used paired whole‑genome bisulphite sequencing and RNA‑seq on wheat landraces to investigate how DNA methylation patterns change during drought stress, revealing antagonistic trends across cytosine contexts and a key demethylation role for ROS1a family members. Gene‑body methylation correlated positively with expression but negatively with stress‑responsive changes, while drought‑induced hyper‑methylation of specific transposable elements, especially the RLX_famc9 LTR retrotransposon, appears to modulate downstream gene regulation via siRNA precursors.
Vacuolar invertase knockout enhances drought tolerance in potato plants
Authors: Roitman, M., Teper-Bamnolker, P., Doron-Faigenboim, A., Sikron, N., Fait, A., Vrobel, O., Tarkowski, P., Moshelion, M., Bocobza, S., Eshel, D.
CRISPR/Cas9 knockout of the vacuolar invertase gene (StVInv) in potato enhanced drought resilience, with mutants maintaining higher stomatal conductance, transpiration, and photosynthetic efficiency, leading to improved agronomic water-use efficiency and biomass under water limitation. Metabolomic profiling showed accumulation of galactinol and raffinose, while ABA levels were reduced, indicating altered osmoprotective and hormonal responses that support sustained growth during drought.
The study examined the pre‑activation state of the rice NLR pair Pik‑1 (sensor) and Pik‑2 (helper) when transiently expressed in Nicotiana benthamiana leaves. Both wild‑type and engineered Pik‑1 variants constitutively associate with Pik‑2 to form ~1 MDa hetero‑oligomeric complexes that localize to the plasma membrane in the absence of effector. These results reveal that some NLRs exist as pre‑assembled membrane‑associated complexes prior to pathogen perception.
Four barley genotypes were examined under simultaneous Fusarium culmorum infection and drought, revealing genotype-dependent Fusarium Head Blight severity and largely additive transcriptomic responses dominated by drought. Co‑expression and hormone profiling linked ABA and auxin to stress‑specific gene modules, and a multiple linear regression model accurately predicted combined‑stress gene expression from single‑stress data, suggesting modular regulation.
The mRNA covalent modification dihydrouridine regulates transcript turnover and photosynthetic capacity during plant abiotic stress
Authors: Yu, L., Melandri, G., Dittrich, A. C., Calleja, S., Rozzi, B., Ganguly, D. R., Palos, K., Srinivasan, A., Brewer, E. K., Fischer, H., Obata, T., Elgawad, H. A., Beemster, G. T. S., Henderson, R., Garcia, C. D., Zhang, X., Stern, D., Eveland, A., Schroeder, S. J., Skirycz, A., Lyons, E., Arnold, E. A., Gregory, B. D., Nelson, A. D. L., Pauli, D.
The study integrates multi-omics data from six Sorghum bicolor accessions under field drought to link RNA covalent modifications (RCMs) with photosynthetic performance, identifying the enzyme SbDUS2 that produces dihydrouridine (DHU) on transcripts. Loss‑of‑function dus2 mutants in Arabidopsis thaliana reveal that DHU deficiency leads to hyperstability of photosynthesis‑related mRNAs, impairing germination, development, and stress‑induced CO2 assimilation. The authors propose DHU as a post‑transcriptional mark that promotes rapid mRNA turnover during abiotic stress, enhancing plant resilience.