The circadian clock gates lateral root development
Authors: Nomoto, S., Mamerto, A., Ueno, S., Maeda, A. E., Kimura, S., Mase, K., Kato, A., Suzuki, T., Inagaki, S., Sakaoka, S., Nakamichi, N., Michael, T. P., Tsukagoshi, H.
The study identifies the circadian clock component ELF3 as a temporal gatekeeper that limits hormone‑induced pericycle proliferation and lateral root development in Arabidopsis thaliana. Time‑resolved transcriptomics, imaging, and genetic analyses show that ELF3 maintains rhythmic expression of key regulators via LNK1 and MADS‑box genes, and that loss of ELF3 disrupts this rhythm, enhancing callus growth and accelerating root organogenesis.
The study reveals that the thermosensor and circadian regulator ELF3 interacts with the PLT3 transcription factor in Arabidopsis root stem cell niches, forming subcellular condensates that sustain quiescent centre and columella stem cell fate. ELF3’s intrinsically disordered prion‑like domains drive condensate formation with PLT3, and PIF3/4 act as nuclear shuttles recruiting ELF3 to nuclear condensates, linking environmental cues to stem cell maintenance.
The study reveals that the microtubule-associated protein MAP70-2 integrates mechanical and biochemical signals to guide division plane orientation during early lateral root primordium formation in Arabidopsis thaliana. Dynamic MAP70-2 localization to cell corners and the cortical division zone precedes cytokinesis, and loss of MAP70-2 results in misoriented divisions and malformed lateral roots, highlighting its role in three‑dimensional differential growth under mechanical constraints.
The study examined how DNA methylation influences cold stress priming in Arabidopsis thaliana, revealing that primed plants exhibit distinct gene expression and methylation patterns compared to non-primed plants. DNA methylation mutants, especially met1 lacking CG methylation, showed altered cold memory and misregulation of the CBF gene cluster, indicating that methylation ensures transcriptional precision during stress recall.
The authors used a bottom‑up thermodynamic modelling framework to investigate how plants decode calcium signals, starting from Ca2+ binding to EF‑hand proteins and extending to higher‑order decoding modules. They identified six universal Ca2+-decoding modules that can explain variations in calcium sensitivity among kinases and provide a theoretical basis for interpreting calcium signal amplitude and frequency in plant cells.
Authors: Baer, M., Zhong, Y., Yu, B., Tian, T., He, X., Gu, L., Huang, X., Gallina, E., Metzen, I. E., Bucher, M., Song, R., Gutjahr, C., SU, Z., Moya, Y., von Wiren, N., Zhang, L., Yuan, L., Shi, Y., Wang, S., Qi, W., Baer, M., Zhao, Z., Li, C., Li, X., Hochholdinger, F., Yu, P.
The study uncovers how arbuscular mycorrhizal (AM) fungi induce lateral root formation in maize by activating ethylene‑responsive transcription factors (ERFs) that regulate pericycle cell division and reshape flavonoid metabolism, lowering inhibitory flavonols. It also shows that the rhizobacterium Massilia collaborates with AM fungi, degrading flavonoids and supplying auxin, thereby creating an integrated ethylene‑flavonoid‑microbe signaling network that can be harnessed to improve nutrient uptake and crop sustainability.
The study used a computer‑vision phenotyping pipeline (EarVision.v2) based on Faster R-CNN to map Ds‑GFP mutant kernels on maize ears and a statistical framework (EarScape) to assess spatial patterns of allele transmission from the apex to the base. They found that alleles causing pollen‑specific transmission defects often show significant spatial biases, whereas Mendelian alleles do not, indicating that reduced pollen fitness can shape the spatial distribution of progeny genotypes in Zea mays.
The study shows that the membrane lipids PI4P, PI(4,5)P2, and phosphatidylserine have distinct spatial and temporal dynamics during lateral root primordium formation in Arabidopsis thaliana, with PI4P acting as a stable basal lipid, PI(4,5)P2 serving as a negative regulator of initiation, and phosphatidylserine increasing after founder cell activation. Using live-cell biosensors, genetic mutants, and an inducible PI(4,5)P2 depletion system, the authors demonstrate that reducing PI(4,5)P2 enhances lateral root initiation and development.
The study engineers Type‑B response regulators to alter their transcriptional activity and cytokinin sensitivity, enabling precise modulation of cytokinin‑dependent traits. Using tissue‑specific promoters, the synthetic transcription factors were deployed in Arabidopsis thaliana to reliably increase or decrease lateral root numbers, demonstrating a modular platform for controlling developmental phenotypes.
The study characterizes the tomato class B heat shock factor SlHSFB3a, revealing its age‑dependent expression in roots and its role in enhancing lateral root density by modulating auxin homeostasis. Overexpression of SlHSFB3a increases lateral root emergence, while CRISPR‑mediated knockouts produce the opposite phenotype, indicating that SlHSFB3a regulates auxin signaling through repression of auxin repressors and activation of the ARF7/LOB20 pathway.