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During lateral root (LR) development, morphological alteration of the developing single LR primordium occurs continuously. Precise observation of this continuous alteration is important for understanding the mechanism involved in single LR development. Recently, we reported that very long-chain fatty acids are important signalling molecules that regulate LR development. In the study, we developed an efficient method to quantify the transition of single LR developmental stages using time-lapse imaging followed by a deep neural network (DNN) analysis. In this ‘insight’ paper, we discuss our DNN method and the importance of time-lapse imaging in studies on plant development. Integrating DNN analysis and imaging is a powerful technique for the quantification of the timing of the transition of organ morphology; it can become an important method to elucidate spatiotemporal molecular mechanisms in plant development.

Abstract The increasing rate of cesarean deliveries warrants obstetric anesthesiologists to deliver high-quality post-cesarean delivery analgesia. The aim of this study was to evaluate the temporal trends in the use of neuraxial morphine for cesarean deliveries and to describe the current postoperative analgesia practices. A retrospective cohort study using nationwide health insurance claims databases was conducted from 2005 to 2020 in Japan. Pregnant women who had undergone cesarean deliveries were included. The annual rate of neuraxial morphine use was extracted and analyzed. Additionally, we explored the patient- and facility-level factors associated with neuraxial morphine use through a multilevel logistic regression analysis. The cohort included 65,208 cesarean delivery cases from 2275 institutions. The prevalence of neuraxial morphine use was 16.0% (95% confidence interval [CI], 15.8–16.3) in the overall cohort. Intrathecal morphine was used in 20.6% (95% CI, 20.2–21.0) of spinal anesthesia cases. The trend in neuraxial morphine use steadily increased from 2005 to 2020. The significant predictors of neuraxial morphine use included spinal anesthesia, recent surgery, large medical facilities, and academic hospitals. Variations in the utilization of postoperative analgesia were observed. Our study described the current trend of neuraxial morphine use and the variation in postoperative analgesia practice in Japan.

Plant root development involves multiple signal transduction pathways. Notably, phytohormones like auxin and cytokinin are well characterized for their molecular mechanisms of action. Reactive oxygen species (ROS) serve as crucial signaling molecules in controlling root development. The transcription factor, UPBEAT1 (UPB1) is responsible for maintaining ROS homeostasis at the root tip, influencing the transition from cell proliferation to differentiation. While UPB1 directly regulates peroxidase expression to control ROS homeostasis, it targets genes other than peroxidases, suggesting its involvement in root growth through non-ROS signals. Our investigation focused on the transcription factor MYB50, a direct target of UPB1, in Arabidopsis thaliana. By analyzing multiple fluorescent proteins and conducting RNA-seq and ChIP-seq, we unraveled a step in the MYB50 regulatory gene network. This analysis, in conjunction with the UPB1 regulatory network, demonstrated that MYB50 directly regulates the expression of PECTIN METHYLESTERASE INHIBITOR 8 (PMEI8). Overexpressing PMEI8, similar to the MYB50, resulted in reduced mature cell length. These findings establish MYB50 as a regulator of root growth within the UPB1 gene regulatory network. Our study presents a model involving transcriptional regulation by MYB50 in the UPB1 regulated root growth system and sheds light on cell elongation via pectin modification.

Summary: Plants tailor immune responses to defend against pathogens with different lifestyles. In this process, antagonism between the immune hormones salicylic acid (SA) and jasmonic acid (JA) optimizes transcriptional signatures specifically to the attacker encountered. Antagonism is controlled by the transcription cofactor NPR1. The indispensable role of NPR1 in activating SA-responsive genes is well understood, but how it functions as a repressor of JA-responsive genes remains unclear. Here, we demonstrate that SA-induced NPR1 is recruited to JA-responsive promoter regions that are co-occupied by a JA-induced transcription complex consisting of the MYC2 activator and MED25 Mediator subunit. In the presence of SA, NPR1 physically associates with JA-induced MYC2 and inhibits transcriptional activation by disrupting its interaction with MED25. Importantly, NPR1-mediated inhibition of MYC2 is a major immune mechanism for suppressing pathogen virulence. Thus, NPR1 orchestrates the immune transcriptome not only by activating SA-responsive genes but also by acting as a corepressor of JA-responsive MYC2.

Abstract Reactive oxygen species (ROS) play important roles as root growth regulators. We previously reported a comprehensive transcriptomic atlas, which we named ROS-map, that revealed ROS-responsible genes in Arabidopsis root tips. By using ROS-map, we have characterised an early ROS response key transcription factor, MYB30, as a regulator of root cell elongation under ROS signals. However, there are other ROS-responsible transcription factors which have the potential to regulate root growth. In the present study, we characterised the function of another early ROS-responsible transcription factor, ANAC032, that was selected from ROS-map. Overexpression of ANAC032 fused with the transcriptional activation domain, VP16, inhibited root growth, especially decreasing cell elongation. By transcriptome analysis, we revealed that ANAC032 regulated many stress-responsible genes in the roots. Intriguingly, ANAC032 upregulated MYB30 and its target genes. The upregulation of MYB30 target genes was completely abolished in the ANAC032-VP16x2 OX and ANAC032 estradiol-inducible line in myb30-2 mutants. Moreover, root growth inhibition was alleviated in ANAC032-OX in myb30-2 mutants. Overall, we characterised an upstream transcription factor, ANAC032, of the MYB30 transcriptional cascade which is a key regulator for root cell elongation under ROS signalling.

Plant development under altered nutritional status and environmental conditions and during attack from invaders is highly regulated by plant hormones at the molecular level by various signaling pathways. Previously, reactive oxygen species (ROS) were believed to be harmful as they cause oxidative damage to cells; however, in the last decade, the essential role of ROS as signaling molecules regulating plant growth has been revealed. Plant roots accumulate relatively high levels of ROS, and thus, maintaining ROS homeostasis, which has been shown to regulate the balance between cell proliferation and differentiation at the root tip, is important for proper root growth. However, when the balance is disturbed, plants are unable to respond to the changes in the surrounding conditions and cannot grow and survive. Moreover, ROS control cell expansion and cell differentiation processes such as root hair formation and lateral root development. In these processes, the transcription factor-mediated gene expression network is important downstream of ROS. Although ROS can independently regulate root growth to some extent, a complex crosstalk occurs between ROS and other signaling molecules. Hormone signals are known to regulate root growth, and ROS are thought to merge with these signals. In fact, the crosstalk between ROS and these hormones has been elucidated, and the central transcription factors that act as a hub between these signals have been identified. In addition, ROS are known to act as important signaling factors in plant immune responses; however, how they also regulate plant growth is not clear. Recent studies have strongly indicated that ROS link these two events. In this review, we describe and discuss the role of ROS signaling in root development, with a particular focus on transcriptional regulation. We also summarize the crosstalk with other signals and discuss the importance of ROS as signaling molecules for plant root development.

One of the major environmental stress factors that affect root growth is salinity. Arabidopsis thaliana, a glycophyte, shows halotropism, whereby it alters the direction of root growth in a non-gravitropic pattern to evade high soil salinity. Asymmetric auxin distribution regulated by the relocation of auxin-efflux carrier proteins is a key cellular event in the halotropic response. However, there are no reports of halotropism in halophytes. Here, we investigated root growth traits in Mesembryanthemum crystallinum (ice plant), under high salinity conditions. We hypothesized that ice plant roots would show halotropic responses different from those of Arabidopsis. Notably, similar to halotropism observed in Arabidopsis, ice plant roots showed continuous root bending under salinity stress. However, the root elongation rate did not change in ice plants. Expression analyses of several genes revealed that auxin transport might be partially involved in ice plant halotropism. This study enhances our understanding of halophyte root adaptation to high salinity stress.