ELONGATED HYPOCOTYL5-mediated light signaling promotes shoot regeneration in Arabidopsis thaliana.

Injured plant somatic tissues regenerate themselves by establishing shoot or root meristems. In Arabidopsis (Arabidopsis thaliana), a two-step culture system ensures regeneration by first promoting the acquisition of pluripotency and subsequently specifying the fate of new meristems. Although previous studies have reported the importance of phytohormones auxin and cytokinin in determining the fate of new meristems, whether and how environmental factors influence this process remains elusive. In this study, we investigated the impact of light signals on shoot regeneration using Arabidopsis hypocotyls as explants. We found that light signals promote shoot regeneration while inhibiting root formation. ELONGATED HYPOCOTYL 5 (HY5), the pivotal transcriptional factor in light signaling, plays a central role in this process by mediating the expression of key genes controlling the fate of new meristems. Specifically, HY5 directly represses root development genes and activates shoot meristem genes, leading to the establishment of shoot progenitor from pluripotent callus. We further demonstrated that the early activation of photosynthesis is critical for shoot initiation, and this is transcriptionally regulated downstream of HY5-dependent pathways. In conclusion, we uncovered the intricate molecular mechanisms by which light signals control the establishment of new meristems through the regulatory network governed by HY5, thus highlighting the influence of light signals on plant developmental plasticity.

Mothra: Multiobjective de novo Molecular Generation Using Monte Carlo Tree Search.

In the field of drug discovery, identifying compounds that satisfy multiple criteria, such as target protein affinity, pharmacokinetics, and membrane permeability, is challenging because of the vast chemical space. Until now, multiobjective optimization via generative models has often involved linear combinations of different reward functions. Linear combinations solve multiobjective optimization problems by turning multiobjective optimization into a single-objective task and causing problems with weighting for each objective. Herein, we propose a scalable multiobjective molecular generative model developed using deep learning techniques. This model integrates the capabilities of recurrent neural networks for molecular generation and Pareto multiobjective Monte Carlo tree search to determine the optimal search direction. Through this integration, our model can generate compounds using enhanced evaluation functions that include important aspects like target protein affinity, drug similarity, and toxicity. The proposed model addresses the limitations of previous linear combination methods, and its effectiveness is demonstrated via extensive experimentation. The improvements achieved in the evaluation metrics underscore the potential utility of our approach toward drug discovery applications. In addition, we provide the source code for our model such that researchers can easily access and use our framework in their own investigations. The source code and pretrained model for Mothra, developed in this study, along with the Docker image for the Pareto front explorer and compound picker, designed to streamline the selection and visualization of optimal chemical compounds, are released under the GNU General Public License v3.0 and available at https://github.com/sekijima-lab/Mothra.

Design and validation of a method for evaluating medical device cleanliness by recovering and quantifying residual proteins on stainless plates.

We recently reported a method for recovering and quantifying residual proteins bound to surfaces of various medical instruments via thermal coagulation under neutral pH and room temperature. The method effectively recovered and solubilised coagulated proteins at high temperatures in dry and humid conditions, with a protein recovery rate of > 90%. This study validated the previous method by comparing residual protein recovery from test samples using a conventional extraction solution (1% SDS, [pH 11.0]) and proposed solution (1% SDS, 10 mM TCEP, and 10 mM HEPES [pH 7.0]). To mimic soiled medical equipment, pseudo-blood-contaminated stainless steel plates were prepared. Residual protein was recovered using conventional and proposed solutions under varying temperature and humidity conditions. Quantitative protein recovery limits were determined at nine facilities. Compared with the conventional solution, the proposed solution recovered proteins more effectively from samples processed at temperatures > 60 °C. However, low recovery rates were observed for samples processed at 95 °C, possibly owing to differences in protein adhesion due to sample and plate-surface properties. Our findings present a method for quantifying residual proteins on medical instruments exposed to high temperatures during use or disinfection. Further studies should standardise test soiling conditions, materials, and solutions to evaluate cleaning methods.

A florigen-expressing subpopulation of companion cells expresses other small proteins and reveals a nitrogen-sensitive FT repressor.

The precise onset of flowering is crucial to ensure successful plant reproduction. The gene FLOWERING LOCUS T (FT) encodes florigen, a mobile signal produced in leaves that initiates flowering at the shoot apical meristem. In response to seasonal changes, FT is induced in phloem companion cells located in distal leaf regions. Thus far, a detailed molecular characterization of the FT-expressing cells has been lacking. Here, we used bulk nuclei RNA-seq and single nuclei RNA (snRNA)-seq to investigate gene expression in FT-expressing cells and other phloem companion cells. Our bulk nuclei RNA-seq demonstrated that FT-expressing cells in cotyledons and in true leaves differed transcriptionally. Within the true leaves, our snRNA-seq analysis revealed that companion cells with high FT expression form a unique cluster in which many genes involved in ATP biosynthesis are highly upregulated. The cluster also expresses other genes encoding small proteins, including the flowering and stem growth inducer FPF1-LIKE PROTEIN 1 (FLP1) and the anti-florigen BROTHER OF FT AND TFL1 (BFT). In addition, we found that the promoters of FT and the genes co-expressed with FT in the cluster were enriched for the consensus binding motifs of NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL REPRESSOR 1 (NIGT1). Overexpression of the paralogous NIGT1.2 and NIGT1.4 repressed FT expression and significantly delayed flowering under nitrogen-rich conditions, consistent with NIGT1s acting as nitrogen-dependent FT repressors. Taken together, our results demonstrate that major FT-expressing cells show a distinct expression profile that suggests that these cells may produce multiple systemic signals to regulate plant growth and development.

Generation of stochastic electromagnetic beams based on modified degenerate cavity lasers.

This study introduces a technique for generating stochastic electromagnetic (SEM) beams using a modified degenerate cavity laser in which one mirror is substituted with a spatial light modulator (SLM). We propose two methods to manipulate the spatial coherence of SEM beams: the first involves adjusting the size of a spatial filter within the laser cavity, which alters the number of oscillating transverse modes and thus varies the spatial coherence. The second method employs phase modulation by applying a dynamic random phase to the SLM. This dual approach allows for precise control over the spatial coherence properties of SEM beams. Experimental results demonstrate the generation of SEM beams using an SLM within a modified degenerate cavity laser and reveal a correlation between two orthogonal polarization components of the beams.

Transcriptomic landscape of seedstick in Arabidopsis thaliana funiculus after fertilisation.

BACKGROUND: In Angiosperms, the continuation of plant species is intricately dependent on the funiculus multifaceted role in nutrient transport, mechanical support, and dehiscence of seeds. SEEDSTICK (STK) is a MADS-box transcription factor involved in seed size and abscission, and one of the few genes identified as affecting funiculus growth. Given the importance of the funiculus to a correct seed development, allied with previous phenotypic observations of stk mutants, we performed a transcriptomic analysis of stk funiculi from floral stage 17, using RNA-sequencing, to infer on the deregulated networks of genes. RESULTS: The generated dataset of differentially expressed genes was enriched with cell wall biogenesis, cell cycle, sugar metabolism and transport terms, all in accordance with stk phenotype observed in funiculi from floral stage 17. We selected eight differentially expressed genes for transcriptome validation using qPCR and/or promoter reporter lines. Those genes were involved with abscission, seed development or novel functions in stk funiculus, such as hormones/secondary metabolites transport. CONCLUSION: Overall, the analysis performed in this study allowed delving into the STK-network established in Arabidopsis funiculus, fulfilling a literature gap. Simultaneously, our findings reinforced the reliability of the transcriptome, making it a valuable resource for candidate genes selection for functional genetic studies in the funiculus. This will enhance our understanding on the regulatory network controlled by STK, on the role of the funiculus and how seed development may be affected by them.

Questioning the Correlation Between Incidence of Hirschsprung Disease And Indications for Rectal Biopsy.

Aim: To review the indications for rectal mucosal/submucosal biopsy (RMSBx) used for diagnosing Hirschsprung's disease (HD) in pediatric patients. Methods: The medical records of all children between 1 and 15 years old assessed for chronic constipation between 2012 and 2022 were reviewed. Until the end of 2018, enema usage (E+) was a major indication for RMSBx. In 2019, laxative use for 3 months irrespective of enema use was added as an indication (L+). To determine the relevance of enema usage, L+ was subdivided by enema usage into (L+E+) and (L+E-) groups. The effect of changing the indications for RMSBx on the incidence of HD was investigated. Results: Of 562 eligible subjects, E+ = 410, L+ = 152; demographics are similar. RMSBx rate in E+ (E+RMSBx) was 36/410 (8.8%) and in L+ (L+RMSBx) was 42/152 (27.6%;) (P < .05). For L+RMSBx, 15/42 were L+E+ and 27/42 were L+E-. HD incidence in E+RMSBx was 8/36 (22.2%; E+HD) and in L+RMSBx was 13/42 (31.0%; L+HD) (p = ns). In L+RMSBx, HD incidence in L+E+ was 5/15 (33.3%; L+E+HD) and in L+E- was 8/27 (29.6%; L+E-HD) (P = ns). Differences in daily bowel motion frequency 6 months postoperatively were not statistically significant; E+HD (1.75/d) versus L+HD (2.03/d) and L+E+HD (1.60/day) versus L+E-HD (2.31/day). Unassisted voluntary defecation was confirmed 12 months postoperatively in 7/8 (87.5%) E+HD, 11/13 (84.6%) L+HD, 4/5 (80.0%) L+E+HD, and 7/8 (87.5%) L-E-HD; differences were not significant. Laxatives were still required in 2/8 (25.0%) E+HD, 3/13 (23.1%) L+HD, in 1/5 (20.0%) in L+E+HD, and 2/8 (25.0%) L+E-HD; differences were not significant. Conclusion: Incidence of HD was higher in L+HD, but not significantly different suggesting that indications for RMSBx have potential to influence incidence of HD and hint that the incidence of HD could actually be higher. Further assessment of additional indications is warranted to diagnose HD with greater accuracy.

Growth of metal nanowire forests controlled through stress fields induced by grain gradients.

Pure metal nanowires (NWs) are one-dimensional nanomaterials with distinctive properties for various applications. Nevertheless, mass-growth forests have not been developed because of vapor pressure limitations, chemical reduction problems, or both. We succeeded in the mass growth of aluminum (Al) NW forests at desired locations by controlling atomic diffusion within the solid film. Whereas prior attention has focused only on how to increase the driving force, we show that focused ion beam irradiation created localized regions of high stress, which provided pathways for atomic diffusion as well as nuclei and driving forces for vertical NW growth. The underlying growth process could in principle be extended to other metals.

Liver Mitochondrial Morphology and Gene Expression as Markers of Liver Reserve: Prognostic Implications for Native Liver Survival in Biliary Atresia.

PURPOSE: Hepatocyte mitochondrial morphology and gene expression were compared between biliary atresia (BA), infantile cholestasis (IC), and normal liver (NL) as prognostic indicators. METHODS: Specimens of liver at portoenterostomy (PE) for BA, from intrahepatic bile duct paucity patients for IC, and from choledochal cyst or hepatoblastoma patients for NL were collected prospectively (P) beginning in 2021 (P-BA = 11, P-IC = 9, P-NL = 7) and retrospectively (R) from paraffin-embedded tissue going back to 1981 (R-BA = 25, R-IC = 9, R-NL = 4). The P-cohort had transmission electron microscopy (TEM) to image mitochondria, immunoblotting for heat shock protein 60 (HSP60), and quantitative PCR (qPCR) for HSP60 and mitochondrial functional genes. Both cohorts had immunofluorescence for HSP60 quantified as a ratio to albumin-positive hepatocytes (ALB) with HSP60/ALB<1.0 as a cutoff limit using ImageJ. RESULTS: HSP60 was significantly lower in BA/IC than NL on qPCR (BA: p < 0.01, IC: p < 0.05) and lower in BA than IC/NL on immunoblotting (p < 0.05). HSP60/ALB was significantly lower in BA than NL/IC (p < 0.001). Despite BA subjects being matched for types of BA and ages at PE, HSP60/ALB did not correlate with jaundice clearance (JC; T-Bil<1.2 mg/dL) but was significantly higher in native liver survivors (NLS) after PE compared with liver transplant (LTx) cases (p < 0.05) and significantly lower in LTx cases achieving JC than NLS achieving JC (p < 0.05). TEM showed BA had significantly more mitochondrial inclusion bodies (p < 0.05) and significantly larger cristae (p < 0.01) than IC/NL. qPCR in BA showed significant repression of mitochondrial functional genes for mRNA stabilization and energy facilitation. CONCLUSION: HSP60/ALB correlates with NLS after PE for BA. LEVEL OF EVIDENCE: II.

Mitochondrial viability in neurogenic bladder urothelium after sigmoidocolocystoplasty. Implications for persistent vesicoureteral reflux.

PURPOSE: We investigated whether inflammatory cell infiltration (ICI), fibrosis, and mitochondrial viability of the neurogenic bladder urothelium are involved in the mechanism of persistent vesicoureteral reflux (VUR) after sigmoidocolocystoplasty (SCP). METHODS: Bladder biopsies obtained 1994-2023 from 62 neurogenic bladder patients were examined by hematoxylin and eosin for ICI, Masson's trichrome for fibrosis, and immunofluorescence for urothelial growth differentiation factor 15 (GDF15; a mitochondrial stress-responsive cytokine) (positive/negative) and heat shock protein 60 (HSP60; a mitochondrial matrix marker) (strong ≥ 50%/weak≤ 50%) expression. GDF15 + /weak HSP60 indicated compromised mitochondrial viability. Cystometry measured neobladder compliance/capacity. RESULTS: Mean ages (years) at SCP and bladder biopsies were 9.4 ± 4.6 and 14.2 ± 7.1, respectively. VUR was present in 38/62 patients (51 ureters) at SCP and resolved with SCP alone in 4/38 patients, with SCP and ureteroneocystostomy in 17/38, and persisted in 17/38. Fibrosis was significantly denser in GDF15 + (n = 24)/weak HSP60 (n = 31) compared with GDF15- (n = 38)/strong HSP60 (n = 31) (p < 0.001 and p < 0.01, respectively). Differences in ICI were significant for GDF15 + vs. GDF15- (p < 0.05) but not for HSP60. Patients with VUR after SCP had higher incidence of GDF15 + /weak HSP60 compared with cases without VUR (p < 0.05 and p < 0.001, respectively). CONCLUSION: Viability of mitochondria appears to be compromised with possible etiologic implications for VUR persisting after SCP.

Alternative Oxidase Alleviates Mitochondrial Oxidative Stress during Limited Nitrate Reduction in Arabidopsis thaliana.

The conversion of nitrate to ammonium, i.e., nitrate reduction, is a major consumer of reductants in plants. Previous studies have reported that the mitochondrial alternative oxidase (AOX) is upregulated under limited nitrate reduction conditions, including no/low nitrate or when ammonium is the sole nitrogen (N) source. Electron transfer from ubiquinone to AOX bypasses the proton-pumping complexes III and IV, thereby consuming reductants efficiently. Thus, upregulated AOX under limited nitrate reduction may dissipate excessive reductants and thereby attenuate oxidative stress. Nevertheless, so far there is no firm evidence for this hypothesis due to the lack of experimental systems to analyze the direct relationship between nitrate reduction and AOX. We therefore developed a novel culturing system for A. thaliana that manipulates shoot activities of nitrate reduction and AOX separately without causing N starvation, ammonium toxicity, or lack of nitrate signal. Using shoots processed with this system, we examined genome-wide gene expression and growth to better understand the relationship between AOX and nitrate reduction. The results showed that, only when nitrate reduction was limited, AOX deficiency significantly upregulated genes involved in mitochondrial oxidative stress, reductant shuttles, and non-phosphorylating bypasses of the respiratory chain, and inhibited growth. Thus, we conclude that AOX alleviates mitochondrial oxidative stress and sustains plant growth under limited nitrate reduction.

Two structurally different oomycete lipophilic microbe-associated molecular patterns induce distinctive plant immune responses.

Plants recognize a variety of external signals and induce appropriate mechanisms to increase their tolerance to biotic and abiotic stresses. Precise recognition of attacking pathogens and induction of effective resistance mechanisms are critical functions for plant survival. Some molecular patterns unique to a certain group of microbes, microbe-associated molecular patterns (MAMPs), are sensed by plant cells as nonself molecules via pattern recognition receptors. While MAMPs of bacterial and fungal origin have been identified, reports on oomycete MAMPs are relatively limited. This study aimed to identify MAMPs from an oomycete pathogen Phytophthora infestans, the causal agent of potato late blight. Using reactive oxygen species (ROS) production and phytoalexin production in potato (Solanum tuberosum) as markers, two structurally different groups of elicitors, namely ceramides and diacylglycerols, were identified. P. infestans ceramides (Pi-Cer A, B, and D) induced ROS production, while diacylglycerol (Pi-DAG A and B), containing eicosapentaenoic acid (EPA) as a substructure, induced phytoalexins production in potato. The molecular patterns in Pi-Cers and Pi-DAGs essential for defense induction were identified as 9-methyl-4,8-sphingadienine (9Me-Spd) and 5,8,11,14-tetraene-type fatty acid (5,8,11,14-TEFA), respectively. These structures are not found in plants, but in oomycetes and fungi, indicating that they are microbe molecular patterns recognized by plants. When Arabidopsis (Arabidopsis thaliana) was treated with Pi-Cer D and EPA, partially overlapping but different sets of genes were induced. Furthermore, expression of some genes is upregulated only after the simultaneous treatment with Pi-Cer D and EPA, indicating that plants combine the signals from simultaneously recognized MAMPs to adapt their defense response to pathogens.

The CRK14 gene encoding a cysteine-rich receptor-like kinase is implicated in the regulation of global proliferative arrest in Arabidopsis thaliana.

Global proliferative arrest (GPA) is a phenomenon in monocarpic plants in which the activity of all aboveground meristems generally ceases in a nearly coordinated manner after the formation of a certain number of fruits. Despite the fact that GPA is a biologically and agriculturally important event, the underlying molecular mechanisms are not well understood. In this study, we attempted to elucidate the molecular mechanism of GPA regulation by identifying the gene responsible for the Arabidopsis mutant fireworks (fiw), causing an early GPA phenotype. Map-based cloning revealed that the fiw gene encodes CYSTEIN-RICH RECEPTOR-LIKE KINASE 14 (CRK14). Genetic analysis suggested that fiw is a missense, gain-of-function allele of CRK14. Since overexpression of the extracellular domain of CRK14 resulted in delayed GPA in the wild-type background, we concluded that CRK14 is involved in GPA regulation. Analysis of double mutants revealed that fiw acts downstream of or independently of the FRUITFULL-APETALA2 (AP2)/AP2-like pathway, which was previously reported as an age-dependent default pathway in GPA regulation. In addition, fiw is epistatic to clv with respect to GPA control. Furthermore, we found a negative effect on WUSCHEL expression in the fiw mutants. These results thus suggest the existence of a novel CRK14-dependent signaling pathway involved in GPA regulation.

Florigen-producing cells express FPF1-LIKE PROTEIN 1 that accelerates flowering and stem growth in long days with sunlight red/far-red ratio in Arabidopsis.

Seasonal changes in spring induce flowering by expressing the florigen, FLOWERING LOCUS T (FT), in Arabidopsis. FT is expressed in unique phloem companion cells with unknown characteristics. The question of which genes are co-expressed with FT and whether they have roles in flowering remains elusive. Through tissue-specific translatome analysis, we discovered that under long-day conditions with the natural sunlight red/far-red ratio, the FT-producing cells express a gene encoding FPF1-LIKE PROTEIN 1 (FLP1). The master FT regulator, CONSTANS (CO), controls FLP1 expression, suggesting FLP1's involvement in the photoperiod pathway. FLP1 promotes early flowering independently of FT, is active in the shoot apical meristem, and induces the expression of SEPALLATA 3 (SEP3), a key E-class homeotic gene. Unlike FT, FLP1 facilitates inflorescence stem elongation. Our cumulative evidence indicates that FLP1 may act as a mobile signal. Thus, FLP1 orchestrates floral initiation together with FT and promotes inflorescence stem elongation during reproductive transitions.

A novel semi-dominant mutation in brassinosteroid signaling kinase1 increases stomatal density.

Stomata play a pivotal role in balancing CO2 uptake for photosynthesis and water loss via transpiration. Thus, appropriate regulation of stomatal movement and its formation are crucial for plant growth and survival. Red and blue light induce phosphorylation of the C-terminal residue of the plasma membrane (PM) H+-ATPase, threonine, in guard cells, generating the driving force for stomatal opening. While significant progress has been made in understanding the regulatory mechanism of PM H+-ATPase in guard cells, the regulatory components for the phosphorylation of PM H+-ATPase have not been fully elucidated. Recently, we established a new immunohistochemical technique for detecting guard-cell PM H+-ATPase phosphorylation using leaves, which was expected to facilitate investigations with a single leaf. In this study, we applied the technique to genetic screening experiment to explore novel regulators for the phosphorylation of PM H+-ATPase in guard cells, as well as stomatal development. We successfully performed phenotyping using a single leaf. During the experiment, we identified a mutant exhibiting high stomatal density, jozetsu (jzt), named after a Japanese word meaning 'talkative'. We found that a novel semi-dominant mutation in BRASSINOSTEROID SIGNALING KINASE1 (BSK1) is responsible for the phenotype in jzt mutant. The present results demonstrate that the new immunohistochemical technique has a wide range of applications, and the novel mutation would provide genetic tool to expand our understanding of plant development mediated by brassinosteroid signaling.

Group C MAP kinases phosphorylate MBD10 to regulate ABA-induced leaf senescence in Arabidopsis.

Abscisic acid (ABA) is a phytohormone that promotes leaf senescence in response to environmental stress. We previously identified methyl CpG-binding domain 10 (MBD10) as a phosphoprotein that becomes differentially phosphorylated after ABA treatment in Arabidopsis. ABA-induced leaf senescence was delayed in mbd10 knockout plants but accelerated in MBD10-overexpressing plants, suggesting that MBD10 positively regulates ABA-induced leaf senescence. ABA-induced phosphorylation of MBD10 occurs in planta on Thr-89, and our results demonstrated that Thr-89 phosphorylation is essential for MBD10's function in leaf senescence. The in vivo phosphorylation of Thr-89 in MBD10 was significantly downregulated in a quadruple mutant of group C MAPKs (mpk1/2/7/14), and group C MAPKs directly phosphorylated MBD10 in vitro. Furthermore, mpk1/2/7/14 showed a similar phenotype as seen in mbd10 for ABA-induced leaf senescence, suggesting that group C MAPKs are the cognate kinases of MBD10 for Thr-89. Because group C MAPKs have been reported to function downstream of SnRK2s, our results indicate that group C MAPKs and MBD10 constitute a regulatory pathway for ABA-induced leaf senescence.

Near-Infrared Photoimmunotherapy Using a Protein Mimetic for EGFR-Positive Salivary Gland Cancer.

Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer therapy based on a monoclonal antibody (mAb) conjugated to a photosensitizer (IR700Dye). The conjugate can be activated by near-infrared light irradiation, causing necrotic cell death with high selectivity. In this study, we investigated NIR-PIT using a small protein mimetic (6-7 kDa, Affibody) which has more rapid clearance and better tissue penetration than mAbs for epidermal growth factor receptor (EGFR)-positive salivary gland cancer (SGC). The level of EGFR expression was examined in vitro using immunocytochemistry and Western blotting. Cell viability was analyzed using the alamarBlue assay. In vivo, the volume of EGFR-positive tumors treated with NIR-PIT using the EGFR Affibody-IR700Dye conjugate was followed for 43 days. It was found that NIR-PIT using the EGFR Affibody-IR700Dye conjugate induced the selective destruction of EGFR-positive SGC cells and restricted the progression of EGFR-positive tumors. We expect that NIR-PIT using the EGFR Affibody-IR700Dye conjugate can efficiently treat EGFR-positive SGC and preserve normal salivary function.

Petal abscission is promoted by jasmonic acid-induced autophagy at Arabidopsis petal bases.

In angiosperms, the transition from floral-organ maintenance to abscission determines reproductive success and seed dispersion. For petal abscission, cell-fate decisions specifically at the petal-cell base are more important than organ-level senescence or cell death in petals. However, how this transition is regulated remains unclear. Here, we identify a jasmonic acid (JA)-regulated chromatin-state switch at the base of Arabidopsis petals that directs local cell-fate determination via autophagy. During petal maintenance, co-repressors of JA signaling accumulate at the base of petals to block MYC activity, leading to lower levels of ROS. JA acts as an airborne signaling molecule transmitted from stamens to petals, accumulating primarily in petal bases to trigger chromatin remodeling. This allows MYC transcription factors to promote chromatin accessibility for downstream targets, including NAC DOMAIN-CONTAINING PROTEIN102 (ANAC102). ANAC102 accumulates specifically at the petal base prior to abscission and triggers ROS accumulation and cell death via AUTOPHAGY-RELATED GENEs induction. Developmentally induced autophagy at the petal base causes maturation, vacuolar delivery, and breakdown of autophagosomes for terminal cell differentiation. Dynamic changes in vesicles and cytoplasmic components in the vacuole occur in many plants, suggesting JA-NAC-mediated local cell-fate determination by autophagy may be conserved in angiosperms.

Broad Chain-Length Specificity of the Alkane-Forming Enzymes NoCER1A and NoCER3A/B in Nymphaea odorata.

Many terrestrial plants produce large quantities of alkanes for use in epicuticular wax and the pollen coat. However, their carbon chains must be long to be useful as fuel or as a petrochemical feedstock. Here, we focus on Nymphaea odorata, which produces relatively short alkanes in its anthers. We identified orthologs of the Arabidopsis alkane biosynthesis genes AtCER1 and AtCER3 in N. odorata and designated them NoCER1A, NoCER3A and NoCER3B. Expression analysis of NoCER1A and NoCER3A/B in Arabidopsis cer mutants revealed that the N. odorata enzymes cooperated with the Arabidopsis enzymes and that the NoCER1A produced shorter alkanes than AtCER1, regardless of which CER3 protein it interacted with. These results indicate that AtCER1 frequently uses a C30 substrate, whereas NoCER1A, NoCER3A/B and AtCER3 react with a broad range of substrate chain lengths. The incorporation of shorter alkanes disturbed the formation of wax crystals required for water-repellent activity in stems, suggesting that chain-length specificity is important for surface cleaning. Moreover, cultured tobacco cells expressing NoCER1A and NoCER3A/B effectively produced C19-C23 alkanes, indicating that the introduction of the two enzymes is sufficient to produce alkanes. Taken together, our findings suggest that these N. odorata enzymes may be useful for the biological production of alkanes of specific lengths. 3D modeling revealed that CER1s and CER3s share a similar structure that consists of N- and C-terminal domains, in which their predicted active sites are respectively located. We predicted the complex structure of both enzymes and found a cavity that connects their active sites.