The SABATH family enzymes are a group of plant-specific methyltransferases that catalyze the methylation of many small molecules, including several plant hormones. While this family originated before the evolution of land plants from streptophyte algae, little is known about its biological function in plant lineages other than angiosperms. Here, we identified 12 SABATH family genes from the liverwort Marchantia polymorpha and found that MpSABATH2 plays a critical role in development. Mpsabath2 mutants were severely inhibited in thallus growth and gemma cup formation, while they spontaneously formed sexual branches under noninductive conditions. These phenotypes resembled the developmental responses to far-red light, which was also supported by transcriptome analysis. Further genetic analysis connected this phenomenon with gibberellin (GA)-related metabolism. Blocking GA biosynthesis partially rescued Mpsabath2 phenotypes, which were restored by treatment with the GA precursor, ent-kaurenoic acid. Given that MpSABATH2 belongs to a phylogenetic clade distinct from previously reported phytohormone-methylating SABATH enzymes, our findings suggest that SABATH family enzymes independently acquired roles in developmental regulation through parallel evolution in land plants.

Gibberellin (GA)-dependent regulation of growth and development is a critical innovation for environmental adaptation that arose during the evolution of land plants. While bioactive GA molecules known in angiosperms have not been detected in bryophytes, intermediates in GA biosynthesis, such as ent-kaurenoic acid (KA), are required for bryophyte development. However, the absence of orthologs of the known GA receptor GIBBERELLIN INSENSITIVE DWARF1 (GID1) in bryophytes suggests the existence of an alternative pathway for the action of GA-related compounds. In the liverwort Marchantia polymorpha, far-red light (FR) responses are mediated by a yet-unknown GA-related compound (termed GAMp). Here we show that MpGRAS10, a GRAS family transcription factor, is likely involved in GAMp signaling. Functional analysis revealed that MpGRAS10 is required for FR responses, including hyponastic thallus growth and gametangiophore formation. The insensitivity of Mpgras10 mutants to KA suggests that MpGRAS10 acts downstream of KA biosynthesis. Moreover, MpGRAS10 gain of function caused morphological and transcriptomic changes similar to FR responses under white-light conditions, as well as increased sensitivity to KA treatment. Phylogenetic analysis demonstrated that MpGRAS10 belongs to a GRAS clade containing orthologs in bryophytes, lycophytes and ferns, but not seed plants. These findings provide insights into the diversity and evolution of GA-related signaling pathways in land plants.

Strigolactones (SLs) are a class of plant hormones that regulate diverse developmental processes and environmental responses. SLs also play important roles as allelochemicals in interactions with arbuscular mycorrhizal fungi (AMF) and root parasitic plants in the rhizosphere. Since their discovery as plant hormones nearly 20 years ago, SL biosynthesis, transport, and signaling have been extensively studied, primarily by characterizing mutants with increased shoot branching and by utilizing reverse genetic approaches in various plant species. Emerging evidence has revealed a series of new components of SL biology, expanding our knowledge of how a single plant species produces various types of SLs with diverse chemical structures and how SLs are released from roots into the soil. However, the bioactive forms of SLs that function as plant hormones and the mechanisms underlying their root-to-shoot transport have not yet been clearly elucidated. In this review, we summarize the current understanding of SL biosynthesis and transport in Arabidopsis thaliana and Oryza sativa. In addition, we discuss the physiological functions of different SL species as plant hormones and rhizosphere signaling molecules, which largely remain unresolved.

Bioactive gibberellins (GAs) are a class of plant hormones that regulate various aspects of plant growth and development, and several key GA deactivation enzymes have been identified. In rice, non-13-hydroxylated GAs have been shown to be deactivated via 16α,17-epoxidation by a cytochrome P450 monooxygenase, ELONGATED UPPERMOST INTERNODE (EUI/CYP714D1). Although 16,17-dihydro-16α,17-epoxyGA4 (16α,17-epoxyGA4), the product of EUI from bioactive GA4, has shown weak bioactivity on rice seedlings, how 16α,17-epoxyGAs are further deactivated remains elusive. Here, we identify the EUI2 gene, which regulates internode elongation in rice, using a map-based cloning strategy. EUI2 encodes an epoxide hydrolase that hydrolyzes 16α,17-epoxyGAs to 16,17-dihydro-16α,17-dihydroxyGAs. The eui2 mutants are taller than wild-type plants but are shorter than the eui mutants. However, the levels of known bioactive GAs in the uppermost internodes are not significantly increased in the eui2 mutants. Instead, we show that the eui2 mutants accumulate 16α,17-epoxyGA4 to high levels. We also show that exogenously applied 16α,17-epoxyGA4 is significantly active in elongating the uppermost internode, although not as potent as GA4. Furthermore, we demonstrate that 16α,17-epoxyGA4 can directly interact with the rice GA receptor, GIBBERELLIN INSENSITIVE DWARF1, in vitro. Taken together, the sequential action of EUI and EUI2 results in the stepwise deactivation of GAs during internode elongation in rice. Our data also suggest that the accumulation of a weakly active GA contributes to the mildly tall phenotype of the eui2 mutants.

Fertilization controls various aspects of cereal growth such as tiller number, leaf size, and panicle size. However, despite such benefits, global chemical fertilizer use must be reduced to achieve sustainable agriculture. Here, based on field transcriptome data from leaf samples collected during rice cultivation, we identify fertilizer responsive genes and focus on Os1900 , a gene orthologous to Arabidopsis thaliana MAX1 , which is involved in strigolactone biosynthesis. Elaborate genetic and biochemical analyses using CRISPR/Cas9 mutants reveal that Os1900 together with another MAX1 -like gene, Os5100 , play a critical role in controlling the conversion of carlactone into carlactonoic acid during strigolactone biosynthesis and tillering in rice. Detailed analyses of a series of Os1900 promoter deletion mutations suggest that fertilization controls tiller number in rice through transcriptional regulation of Os1900 , and that a few promoter mutations alone can increase tiller numbers and grain yields even under minor-fertilizer conditions, whereas a single defective os1900 mutation does not increase tillers under normal fertilizer condition. Such Os1900 promoter mutations have potential uses in breeding programs for sustainable rice production.

Strigolactones (SLs) are a class of plant hormones that regulate many aspects of plant growth and development. SLs also improve symbiosis with arbuscular mycorrhizal fungi (AMF) in the rhizosphere. Recent studies have shown that the DWARF14-LIKE (D14L)/KARRIKIN-INSENSITIVE2 (KAI2) family, paralogs of the SL receptor D14, are required for AMF colonization in several flowering plants, including rice. In this study, we found that (-)-GR5, a 2 ' S-configured enantiomer of a synthetic SL analog (+)-GR5, significantly activated SL biosynthesis in rice roots via D14L. This result is consistent with a recent report, showing that the D14L pathway positively regulates SL biosynthesis in rice. In fact, the SL levels tended to be lower in the roots of the d14l mutant under both inorganic nutrient-deficient and -sufficient conditions. We also show that the increase in SL levels by (-)-GR5 was observed in other mycorrhizal plant species. In contrast, the KAI2 pathway did not upregulate the SL level and the expression of SL biosynthetic genes in Arabidopsis, a non-mycorrhizal plant. We also examined whether the KAI2 pathway enhances SL biosynthesis in the liverwort Marchantia paleacea, where SL functions as a rhizosphere signaling molecule for AMF. However, the SL level and SL biosynthetic genes were not positively regulated by the KAI2 pathway. These results imply that the activation of SL biosynthesis by the D14L/KAI2 pathway has been evolutionarily acquired after the divergence of bryophytes to efficiently promote symbiosis with AMF, although we cannot exclude the possibility that liverworts have specifically lost this regulatory system.

Objectives: We surveyed and reported low protective equipment usage and insufficient knowledge among endoscopy-fluoroscopy departments in Japan in 2020. Two years later, we conducted a follow-up survey of doctors, nurses, and technologists in Japan. Methods: We conducted a questionnaire survey on radiation protection from May to June 2022. The participants were medical staff, including doctors, nurses, and radiological and endoscopy technicians in endoscopy-fluoroscopy departments. The questionnaire included 17 multiple-choice questions divided into three parts: background, equipment, and knowledge. Results: We surveyed 464 subjects from 34 institutions. There were 267 doctors (58%), 153 nurses (33%), and 44 technologists (9%). The rate of wearing a lead apron was 98% in this study. The rates of wearing a thyroid collar, lead glasses, and radiation dosimeter were 27%, 35%, and 74%, respectively. The trend of the protective equipment rate was similar to that of our previous study; however, radiation dosimetry among doctors was still low at 58%. The percentage of subjects who knew the radiation exposure (REX) dose of each procedure was low at 18%. Seventy-six percent of the subjects attended lectures on radiation protection, and 73% knew about the three principles of radiation protection; however, the concept of diagnostic reference levels was not well known (18%). Approximately 60% of the subjects knew about the exposure dose increasing cancer mortality (63%) and the 5-year lens REX limit (56%). Conclusions: There was some improvement in radiation protection equipment or education, but relatively little compared to the 2020 survey of endoscopy departments.

DWARF14 (D14) and HTL/KAI2 (KAI2) are paralogous receptors in the α/β-hydrolase superfamily. D14 is the receptor for a class of plant hormones, strigolactones (SLs), and KAI2 is the receptor for the smoke-derived seed germination inducer, Karrikin (KAR), in Arabidopsis. Germinone (Ger) was previously reported as a KAI2 agonist with germination-inducing activity for thermo-inhibited Arabidopsis seed. However, Ger was not specific to KAI2, and could also bind to D14. It was reported that SL analogs with a desmethyl-type D-ring structure are specifically recognized by KAI2. On the basis of this observation, we synthesized a desmethyl-type germinone (dMGer). We found that dMGer is highly specific to KAI2. Moreover, dMGer induced Arabidopsis seed germination more effectively than did Ger. In addition, dMGer induced the seed germination of Arabidopsis in a manner independently of GA, a well-known germination inducer in plants.

Gibberellins (GAs) are key phytohormones that regulate growth, development, and environmental responses in angiosperms. From an evolutionary perspective, all major steps of GA biosynthesis are conserved among vascular plants, while GA biosynthesis intermediates such as ent-kaurenoic acid (KA) are also produced by bryophytes. Here, we show that in the liverwort Marchantia polymorpha, KA and GA(12) are synthesized by evolutionarily conserved enzymes, which are required for developmental responses to far-red light (FR). Under FR-enriched conditions, mutants of various biosynthesis enzymes consistently exhibited altered thallus growth allometry, delayed initiation of gametogenesis, and abnormal morphology of gamete-bearing structures (gametangiophores). By chemical treatments and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses, we confirmed that these phenotypes were caused by the deficiency of some GA-related compounds derived from KA, but not bioactive GAs from vascular plants. Transcriptome analysis showed that FR enrichment induced the up-regulation of genes related to stress responses and secondary metabolism in M. polymorpha, which was largely dependent on the biosynthesis of GA-related compounds. Due to the lack of canonical GA receptors in bryophytes, we hypothesize that GA-related compounds are commonly synthesized in land plants but were co-opted independently to regulate responses to light quality change in different plant lineages during the past 450 million years of evolution.

The level of bioactive gibberellins (GAs) in plants is regulated partly by their inactivation, mainly by the action of GA 2-oxidases (GA2oxs). This study identified three new GA2ox genes in barley: HvGA2ox1, HvGA2ox3 and HvGA2ox6. Analysis of their nucleotide and putative amino acid sequences revealed that they share high sequence identity with other plant GA2oxs and their corresponding proteins. Phylogenetic analysis revealed the HvGA2ox1, HvGA2ox3 and HvGA2ox6 belong to GA2ox structural classes II, I, and III, respectively. Feeding the HvGA2ox1 and HvGA2ox3 recombinant proteins with the C19-GAs, GA1 and GA20, resulted in the production of GA8 and GA29, respectively, with no product detected when they were fed with the C20-GA, GA12. Whereas the HvGA2ox6 recombinant protein was able to convert GA12 to GA110, and no product was detected when it was fed with GA1 or GA20. HvGA2ox1 and HvGA2ox3 were highly expressed in internodes and the endosperm of maturing seeds while HvGA2ox6 was predominantly expressed in the embryos. Salinity stress upregulated the expression of all three genes in seedling tissues. Our results indicate that HvGA2ox1, HvGA2ox3 and HvGA2ox6 encode functional GA2oxs that can regulate GA levels, and therefore growth and development of a barley plant, and its interaction with environment.

Karrikins are smoke-derived butenolides that induce seed germination and photomorphogenesis in a wide range of plants.1-3 KARRIKIN INSENSITIVE2 (KAI2), a paralog of a strigolactone receptor, perceives karrikins or their metabolized products in Arabidopsis thaliana.4-7 Furthermore, KAI2 is thought to perceive an uniden-tified plant hormone, called KAI2 ligand (KL).8,9 KL signal is transduced via the interaction between KAI2, MORE AXILLARY GROWTH2 (MAX2), and SUPPRESSOR of MORE AXILLARY GROWTH2 1 LIKE family pro-teins (SMXLs), followed by the degradation of SMXLs.4,7,10-14 This signaling pathway is conserved both in A. thaliana and the bryophyte Marchantia polymorpha.14 Although the KL signaling pathway is well charac-terized, the KL metabolism pathways remain poorly understood. Here, we show that DIENELACTONE HYDROLASE LIKE PROTEIN1 (DLP1) is a negative regulator of the KL pathway in M. polymorpha. The KL signal induces DLP1 expression. DLP1 overexpression lines phenocopied the Mpkai2a and Mpmax2 mutants, while dlp1 mutants phenocopied the Mpsmxl mutants. Mutations in the KL signaling genes largely suppressed these phenotypes, indicating that DLP1 acts upstream of the KL signaling pathway, although DLP1 also has KL pathway-independent functions. DLP1 exhibited enzymatic activity toward a potential sub-strate, suggesting the possibility that DLP1 works through KL inactivation. Investigation of DLP1 homologs in A. thaliana revealed that they do not play a major role in the KL pathway, suggesting different mechanisms for the KL signal regulation. Our findings provide new insights into the regulation of the KL signal in M. polymorpha and the evolution of the KL pathway in land plants.

Background and Aim Despite the widespread use of endoscopic submucosal dissection (ESD) for early gastric cancer, post-ESD bleeding remains a significant problem. Intragastric pH plays an important role in intragastric bleeding. Because gastric acid secretion contributes to intragastric pH, both the presence or absence of Helicobacter pylori infection and the degree of gastric mucosal atrophy may affect bleeding. The present study aimed to clarify the relationship between post-ESD bleeding and the degree of gastric mucosal atrophy based on H. pylori infection status. Methods We included 8170 patients who underwent ESD for early gastric cancer at 33 hospitals in Japan from November 2013 to October 2016. We analyzed the risk factors contributing to post-ESD bleeding. Results There were 3935 H. pylori-positive patients and 4235 H. pylori-negative patients. A nonsevere degree of gastric mucosal atrophy was an independent risk factor for post-ESD bleeding in H. pylori-negative patients (odds ratio: 1.51, P = 0.007), but not in H. pylori-positive patients (odds ratio: 0.91, P = 0.600). Further, in H. pylori-negative, but not H. pylori-positive, patients, the rate of post-ESD bleeding increased in a stepwise manner for patients continuing antithrombotic drug use, patients who withdrew antithrombotic drug use, and antithrombotic drug nonusers. Conclusions Nonsevere gastric mucosal atrophy was a risk factor for post-ESD bleeding in early gastric cancer in H. pylori-negative patients but not in H. pylori-positive patients.

Previous reports have shown favorable performance of artificial intelligence (AI) systems for diagnosing esophageal squamous cell carcinoma (ESCC) compared with endoscopists. However, these findings don’t reflect performance in clinical situations, as endoscopists classify lesions based on both magnified and non-magnified videos, while AI systems often use only a few magnified narrow band imaging (NBI) still images. We evaluated the performance of the AI system in simulated clinical situations. We used 25,048 images from 1433 superficial ESCC and 4746 images from 410 noncancerous esophagi to construct our AI system. For the validation dataset, we took NBI videos of suspected superficial ESCCs. The AI system diagnosis used one magnified still image taken from each video, while 19 endoscopists used whole videos. We used 147 videos and still images including 83 superficial ESCC and 64 non-ESCC lesions. The accuracy, sensitivity and specificity for the classification of ESCC were, respectively, 80.9% [95% CI 73.6–87.0], 85.5% [76.1–92.3], and 75.0% [62.6–85.0] for the AI system and 69.2% [66.4–72.1], 67.5% [61.4–73.6], and 71.5% [61.9–81.0] for the endoscopists. The AI system correctly classified all ESCCs invading the muscularis mucosa or submucosa and 96.8% of lesions ≥ 20 mm, whereas even the experts diagnosed some of them as non-ESCCs. Our AI system showed higher accuracy for classifying ESCC and non-ESCC than endoscopists. It may provide valuable diagnostic support to endoscopists.

In flowering plants, strigolactones (SLs) have dual functions as hormones that regulate growth and development, and as rhizosphere signaling molecules that induce symbiosis with arbuscular mycorrhizal (AM) fungi. Here, we report the identification of bryosymbiol (BSB), an SL from the bryophyte Marchantia paleacea. BSB is also found in vascular plants, indicating its origin in the common ancestor of land plants. BSB synthesis is enhanced at AM symbiosis permissive conditions and BSB deficient mutants are impaired in AM symbiosis. In contrast, the absence of BSB synthesis has little effect on the growth and gene expression. We show that the introduction of the SL receptor of Arabidopsis renders M. paleacea cells BSB-responsive. These results suggest that BSB is not perceived by M. paleacea cells due to the lack of cognate SL receptors. We propose that SLs originated as AM symbiosis-inducing rhizosphere signaling molecules and were later recruited as plant hormone.

Gibberellins (GAs) are a group of diterpenoid plant hormones that control plant growth and development at various stages. Biologically active GAs share the common structures of a 3β-hydroxy group, a carboxy group at C-6, and a γ-lactone between C-4 and C-10. Hydroxylation at C-2β is a major deactivation step in many plant species, and hydroxylation at C-13 has been shown to weaken the binding affinity of GAs to their receptor proteins. In rice, bioactive GA4 has also been shown to be deactivated through 16α,17-epoxidation. Moreover, 16,17-dihydro-16α,17-dihydroxy GA4 has been identified as an aglycon of its glucoside from rice. However, our knowledge on the biological activity of 16,17-epoxidized GAs is currently limited to 16,17-dihydro-16α,17-epoxy GA4. Moreover, the bioactivity of 16,17-dihydro-16α,17-dihydroxy GA4 remains unknown. Here, we synthesized 16,17-epoxidized or dihydroxylated GA derivatives and performed a structure–activity relationship study using rice seedlings. 16,17-Epoxidation of bioactive GA1 and GA4 reduced their activity to promote elongation of rice leaf sheaths. Moreover, 16,17-dihydroxylation significantly decreased the activities of 16,17-dihydro-16α,17-epoxy GAs. These results suggest that GAs are deactivated in a stepwise manner via 16,17-epoxidation and hydrolysis of these epoxy groups.

Previous studies have shown that treatment of mammalian cells with phospholipase A(2) (PLA(2)) antagonists cause the normally interconnected Golgi ribbon to break up into large fragments of stacked Golgi cisternae ("mini-stacks") that remain located in the juxtanuclear region. Using the reversible PLA(2) antagonist, ONO-RS-082 (ONO) and live-cell, time-lapse microscopy to image the Golgi reassembly process, we found that Golgi mini-stacks underwent a burst of membrane tubule formation following washout of ONO: before washout only 4.3+/-3.8 tubules/cell/10 min were formed, whereas after washout 29.9+/-11.9 tubules/cell/10 min formed. These membranes tubules formed bridges between physically separate mini-stacks, thus mediating their coalescence into intact Golgi ribbons. Formation of inter-stack tubules and an intact Golgi ribbon was also facilitated by microtubules because treatment with nocodazole significantly inhibited both processes. This microtubule-dependent process was also dependent on dynein because the dynein inhibitor nordihydroguaiaretic acid (NDGA) inhibited reassembly. These studies show that a late stage of Golgi assembly occurs via membrane tubules, whose formation is dependent on PLA(2) activity and microtubules. Considering these results together, we concluded that the maintenance and assembly of normal Golgi architecture is dependent on the PLA(2)-mediated, dynamic formation of inter-Golgi membrane tubules.

Significance Strigolactones (SLs) are a group of apocarotenoid hormones, which regulates shoot branching and other diverse developmental processes in plants. The major bioactive form(s) of SLs as endogenous hormones has not yet been clarified. Here, we identify an Arabidopsis methyltransferase, CLAMT, responsible for the conversion of an inactive precursor to a biologically active SL that can interact with the SL receptor in vitro. Reverse genetic analysis showed that this enzyme plays an essential role in inhibiting shoot branching. This mutant also contributed to specifying the SL-related metabolites that could move from root to shoot in grafting experiments. Our work has identified a key enzyme necessary for the production of the bioactive form(s) of SLs.

AbstractBackground and aimsIt is essential for endoscopists, technologists, and nurses to understand radiation protection. However, protective equipment usage is still low, and there is little awareness of radiation protection in practice.MethodsWe conducted a questionnaire survey on radiation protection from January to February 2020. The participants were medical staff, including medical doctors, nurses, and radiological and endoscopy technician in endoscopy‐fluoroscopy departments. The questionnaire included 14 multiple‐choice questions divided among three parts: background, equipment, and knowledge.ResultsWe surveyed a total of 282 subjects from 26 institutions. There were 168 medical doctors (60%), 90 nurses (32%), and 24 technologists (9%). Although almost all staff members (99%) always wore a lead apron, only a few wore a thyroid collar (32%) and lead glasses (21%). The rate of wearing a radiation dosimeter was insufficient (69%), especially among doctors (52%). A few subjects knew the radiation exposure dose of each procedure (15%), and slightly over half had attended lectures on radiation protection (64%) and knew about the three principles of radiation protection (59%). Protection adherence did not differ by years of experience, knowledge of fluoroscopy, awareness of radiation exposure doses, or attendance at basic lectures on radiation protection. However, medical doctors who were aware of the radiation exposure dose of each procedure were significantly more likely to wear dosimeters than those who were not (p = 0.0008).ConclusionMedical staff in endoscopy departments in Japan do not have enough radiation protection equipment or education.

Summary Root parasitic plants such as Striga, Orobanche, and Phelipanche spp. cause serious damage to crop production world‐wide. Deletion of the Low Germination Stimulant 1 (LGS1) gene gives a Striga‐resistance trait in sorghum (Sorghum bicolor). The LGS1 gene encodes a sulfotransferase‐like protein, but its function has not been elucidated. Since the profile of strigolactones (SLs) that induce seed germination in root parasitic plants is altered in the lgs1 mutant, LGS1 is thought to be an SL biosynthetic enzyme. In order to clarify the enzymatic function of LGS1, we looked for candidate SL substrates that accumulate in the lgs1 mutants and performed in vivo and in vitro metabolism experiments. We found the SL precursor 18‐hydroxycarlactonoic acid (18‐OH‐CLA) is a substrate for LGS1. CYP711A cytochrome P450 enzymes (SbMAX1 proteins) in sorghum produce 18‐OH‐CLA. When LGS1 and SbMAX1 coding sequences were co‐expressed in Nicotiana benthamiana with the upstream SL biosynthesis genes from sorghum, the canonical SLs 5‐deoxystrigol and 4‐deoxyorobanchol were produced. This finding showed that LGS1 in sorghum uses a sulfo group to catalyze leaving of a hydroxyl group and cyclization of 18‐OH‐CLA. A similar SL biosynthetic pathway has not been found in other plant species.