An ancient alkalinization factor informs Arabidopsis root development
Authors: Xhelilaj, K., von Arx, M., Biermann, D., Parvanov, A., Faiss, N., Monte, I., Klingelhuber, F., Zipfel, C., Timmermans, M., Oecking, C., Gronnier, J.
The study identifies members of the REMORIN protein family as inhibitors of plasma membrane H⁺‑ATPases, leading to extracellular pH alkalinization that modulates cell surface processes such as steroid hormone signaling and coordinates root developmental transitions in Arabidopsis thaliana. This inhibition represents an ancient mechanism predating root evolution, suggesting that extracellular pH patterning has shaped plant morphogenesis.
The study identified a heat‑responsive exon‑skipping event in the basic Helix‑Loop‑Helix domain of the transcription factor PIF4, which reduces PIF4 activity and promotes photomorphogenic traits in etiolated seedlings. This reveals a novel post‑transcriptional mechanism by which plants modulate PIF4 function during heat stress.
The study evaluated how stomatal anatomy and physiological efficiency influence wheat heat tolerance across multi‑environment field trials with 200 genotypes, using early versus delayed sowing to impose temperature stress. Findings revealed a decoupling between anatomical capacity (gsmax) and actual conductance (gs, gse) under heat, plastic shifts toward smaller, denser stomata, and identified 125 QTL linked to stomatal traits, suggesting targets for breeding climate‑resilient wheat.
Quantitative trait locus mapping of root exudate metabolome in a Solanum lycopersicum Moneymaker x S. pimpinellifolium RIL population and their putative links to rhizosphere microbiome
Authors: Kim, B., Kramer, G., Leite, M. F. A., Snoek, B. L., Zancarini, A., Bouwmeester, H.
The study used untargeted metabolomics and QTL mapping in a tomato recombinant inbred line population to characterize root exudate composition and identify genetic loci controlling specific metabolites. It reveals domestication-driven changes in exudate profiles and links metabolic QTLs with previously reported microbial QTLs, suggesting a genetic basis for shaping the root microbiome.
The study identified a critical two‑week window of elevated maternal temperature during weeks 4–5 after flowering that delays dormancy release in weedy rice seeds. Controlled‑environment and field transplant experiments showed that this late‑reproductive‑stage heat exposure postpones germination after after‑ripening, providing insight for predicting seed behavior and improving weed management strategies.
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.
Using a forward genetic screen of 284 Arabidopsis thaliana accessions, the study identified extensive natural variation in root endodermal suberin and pinpointed the previously unknown gene SUBER GENE1 (SBG1) as a key regulator. GWAS and protein interaction analyses revealed that SBG1 controls suberin deposition by binding type‑one protein phosphatases (TOPPs), with disruption of this interaction or TOPP loss‑of‑function altering suberin levels, linking the pathway to ABA signaling.
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 examined DNA methylation dynamics in Arabidopsis thaliana shoots and roots under heat, phosphate deficiency, and combined stress using whole-genome bisulfite sequencing, small RNA‑seq, and RNA‑seq. Distinct stress‑specific methylation patterns were identified, with heat and combined stress causing CHH hypomethylation, phosphate deficiency causing hyper‑ and hypomethylation in shoots and roots respectively, and the combined stress exhibiting a unique signature independent of additive effects. Methylation changes were concentrated in transposable elements and regulatory regions, implicating RdDM and CMT2 pathways and suggesting a role in chromatin accessibility rather than direct transcriptional control.
The study characterizes the liverwort-specific NPR protein (MpNPR) in Marchantia polymorpha, demonstrating that it controls oil body formation and confers resistance to gastropod herbivory through interaction with the transcription factor MpERF13. Loss- or gain-of-function of MpNPR disrupts MpERF13‑dependent gene expression and compromises defense against snail feeding, revealing a lineage‑specific immune pathway distinct from tracheophyte NPR functions.