PHO2 suppresses arbuscular mycorrhizal symbiosis in high phosphate conditions
Authors: Birch, S., Perryman, S., Ellison, E., Foreman, N., Mekjan, N., Williams, A., Bate-Weldon, M., Ralfs, T., Pucker, B., Whiting, M., Hope, M. S., Wallington, E., Field, K., Choi, J.
The study identifies the rice E2 ubiquitin‑conjugating enzyme PHO2 as a key negative regulator of arbuscular mycorrhizal (AM) colonisation under high phosphate conditions. pho2 mutants in Oryza sativa (and Nicotiana benthamiana) maintain AM fungal entry and exhibit enhanced direct and symbiotic phosphate accumulation, linked to sustained expression of AM‑related genes despite phosphate sufficiency.
Light on its feet: Acclimation to high and low diurnal light is flexible in Chlamydomonas reinhardtii
Authors: Dupuis, S., Chastain, J. L., Han, G., Zhong, V., Gallaher, S. D., Nicora, C. D., Purvine, S. O., Lipton, M. S., Niyogi, K. K., Iwai, M., Merchant, S. S.
The study examined how prior light‑acclimation influences the fitness and rapid photoprotective reprogramming of Chlamydomonas during transitions between low and high diurnal light intensities. While high‑light‑acclimated cells struggled to grow and complete the cell cycle after shifting to low light, low‑light‑acclimated cells quickly remodeled thylakoid ultrastructure, enhanced photoprotective quenching, and altered photosystem protein levels, recovering chloroplast function within a single day. Transcriptomic and proteomic profiling revealed swift induction of stress‑response genes, indicating high flexibility in diurnal light acclimation.
Drought drives reversible disengagement of root-mycorrhizal symbiosis
Authors: Akmakjian, G. Z., Nozue, K., Nakayama, H., Borowsky, A. T., Morris, A. M., Baker, K., Canto-Pastor, A., Paszkowski, U., Sinha, N., Brady, S., Bailey-Serres, J.
The study shows that during drought, rice (Oryza sativa) downregulates nutrient acquisition and arbuscular mycorrhizal (AM) symbiosis genes, causing the fungal partner to enter metabolic quiescence and retract hyphae, but upon re-watering the symbiosis is rapidly reactivated. This reversible dynamic suggests that plant‑fungus mutualisms are fragile under fluctuating water availability.
DECREASE IN DNA METHYLATION 1-mediated epigenetic regulation maintains gene expression balance required for heterosis in Arabidopsis thaliana
Authors: Matsuo, K., Wu, R., Yonechi, H., Murakami, T., Takahashi, S., Kamio, A., Akter, M. A., Kamiya, Y., Nishimura, K., Matsuura, T., Tonosaki, K., Shimizu, M., Ikeda, Y., Kobayashi, H., Seki, M., Dennis, E. S., Fujimoto, R.
The study demonstrates that the chromatin remodeler DDM1 is essential for biomass heterosis in Arabidopsis thaliana hybrids, as loss of DDM1 function leads to reduced rosette growth and extensive genotype‑specific transcriptomic and DNA methylation changes. Whole‑genome bisulfite sequencing revealed widespread hypomethylation in ddm1 mutants, while salicylic acid levels were found unrelated to heterosis, indicating that epigenetic divergence, rather than SA signaling, underpins hybrid vigor.
The study employed computational approaches to characterize the SUMOylation (ULP) machinery in Asian rice (Oryza sativa), analyzing phylogenetic relationships, transcriptional patterns, and protein structures across the reference genome, a population panel, and wild relatives. Findings reveal an expansion of ULP genes in cultivated rice, suggesting selection pressure during breeding and implicating specific ULPs in biotic and abiotic stress responses, providing resources for rice improvement.
The study evaluated barley stripe mosaic virus (BSMV) and foxtail mosaic virus (FoMV) vectors for virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX) in several Oryza sativa cultivars, finding that neither vector altered gene expression despite successful assays in wheat and extensive optimization. The lack of photobleaching with BSMV-PDS and absent GFP fluorescence with FoMV suggest intrinsic resistance mechanisms in rice, highlighting species-specific limitations of virus-enabled reverse genetics and the need for alternative vectors.
The study measured flower opening time and flower exposure duration (FED) in rice cultivars and performed controlled crossing experiments under short‑day and long‑day conditions, finding that when FED overlap exceeds ~20 min, cross‑pollination frequency often exceeds 60 % and can reach 100 %. These results overturn the long‑standing view that rice cross‑pollination is <2 % and highlight the need to investigate genetic factors underlying F1 sterility.
The study applied a progressive, sublethal drought treatment to Arabidopsis thaliana, collecting time‑resolved phenotypic and transcriptomic data. Machine‑learning analysis revealed distinct drought stages driven by multiple overlapping transcriptional programs that intersect with plant aging, and identified high‑explanatory‑power transcripts as biomarkers rather than causal agents.
Salt stress strongly suppresses root growth in Festuca rubra while sparing shoot development. Transcriptome profiling identified over 68,000 differentially expressed genes, with up‑regulated genes enriched in methionine, melatonin, and suberin biosynthesis and down‑regulated genes involved in gibberellin, ABA, and sugar signaling, indicating extensive hormonal and metabolic reprogramming. Paradoxical regulation of gibberellin and ethylene pathways suggests a finely tuned balance between growth and stress responses.
Gain and loss of gene function shaped the nickel hyperaccumulation trait in Noccaea caerulescens
Authors: Belloeil, C., Garcia de la Torre, V. S., Contreras Aguilera, R., Kupper, H., Lopez-Roques, C., Iampetro, C., Vandecasteele, C., Klopp, C., Launay-Avon, A., Leemhuis, W., Yamjabok, J., van den Heuvel, J., Aarts, M. G. M., Quintela Sabaris, C., Thomine, S., MERLOT, S.
The study presents a high-quality genome assembly for the nickel hyperaccumulator Noccaea caerulescens and uses it as a reference for comparative transcriptomic analyses across different N. caerulescens accessions and the non‑accumulating relative Microthlaspi perfoliatum. It identifies a limited set of metal transporters (NcHMA3, NcHMA4, NcIREG2, and NcIRT1) whose elevated expression correlates with hyperaccumulation, and demonstrates that frameshift mutations in NcIRT1 can abolish the trait, indicating an ancient, transporter‑driven origin of nickel hyperaccumulation.