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 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 profiled the maize (Zea mays) endosperm transcriptome for the first four days after pollination using laser-capture microdissection, revealing temporal co‑expression modules including a fertilization‑activated subset. Network analyses linked MYB‑related transcription factors to basal endosperm transfer layer (BETL) differentiation and E2F transcription factors, together with TOR‑dependent sugar sensing, to early endosperm proliferation and kernel size variation.
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.
RNA sequencing of the halophyte Salicornia europaea revealed that combined hypoxia‑salt stress triggers a unique transcriptional response, with 16% of genes specifically altered and distinct synergistic, antagonistic, and additive effects across functional pathways. Metabolic analyses indicated enhanced sucrose and trehalose metabolism, a shift toward lactate fermentation, and increased proline synthesis, highlighting complex regulatory strategies for coping with concurrent stresses.
In a controlled dry-down experiment, Arabis sagittata showed significantly higher recovery from drought than the endangered Arabis nemorensis, a difference that could not be traced to a single major QTL, indicating a polygenic basis. Transcriptome and small‑RNA sequencing revealed that A. sagittata mounts a stronger transcriptional response, including species‑specific regulation of the conserved drought miRNA miR408, and machine‑learning identified distinct cis‑regulatory motif patterns underlying these divergent stress‑response networks.
The study examined whether colonisation by the arbuscular mycorrhizal fungus Rhizophagus irregularis primes immune responses in barley against the leaf rust pathogen Puccinia hordei. While AMF did not affect disease severity or plant growth, co‑infected leaves showed heightened expression of defence genes and transcriptome reprogramming, including altered protein ubiquitination, indicating a priming mechanism. These results highlight transcriptional and post‑translational pathways through which AMF can enhance barley disease resistance for sustainable crop protection.
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.