Effect of Chemical Composition on the Thermoplastic Formability and Nanoindentation of Ti-Based Bulk Metallic Glasses.

A series of Ti41Zr25Be34-xNix (x = 4, 6, 8, 10 at.%) and Ti41Zr25Be34-xCux (x = 4, 6, 8 at.%) bulk metallic glasses were investigated to examine the influence of Ni and Cu content on the viscosity, thermoplastic formability, and nanoindentation of Ti-based bulk metallic glasses. The results demonstrate that Ti41Zr25Be30Ni4 and Ti41Zr25Be26Cu8 amorphous alloys have superior thermoplastic formability among the Ti41Zr25Be34-xNix and Ti41Zr25Be34-xCux amorphous alloys due to their low viscosity in the supercooled liquid region and wider supercooled liquid region. The hardness and modulus exhibit obvious variations with increasing Ni and Cu content in Ti-based bulk metallic glasses, which can be attributed to alterations in atomic density. Optimal amounts of Ni and Cu in Ti-based bulk metallic glasses enhance thermoplastic formability and mechanical properties. The influence of Ni and Cu content on the hardness of Ti-based bulk metallic glasses is discussed from the perspective of the mean atomic distance.

Ultrasensitive and ultrastretchable metal crack strain sensor based on helical polydimethylsiloxane.

The majority of crack sensors do not offer simultaneously both a significant stretchability and an ultrahigh sensitivity. In this study, we present a straightforward and cost-effective approach to fabricate metal crack sensors that exhibit exceptional performance in terms of ultrahigh sensitivity and ultrahigh stretchability. This is achieved by incorporating a helical structure into the substrate through a modeling process and, subsequently, depositing a thin film of gold onto the polydimethylsiloxane substrate via sputter deposition. The metal thin film is then pre-stretched to generate microcracks. The sensor demonstrates a remarkable stretchability of 300%, an exceptional sensitivity with a maximum gauge factor reaching 107, a rapid response time of 158 ms, minimal hysteresis, and outstanding durability. These impressive attributes are attributed to the deliberate design of geometric structures and careful selection of connection types for the sensing materials, thereby presenting a novel approach to fabricating stretchable and highly sensitive crack-strain sensors. This work offers a universal platform for constructing strain sensors with both high sensitivity and stretchability, showing a far-reaching significance and influence for developing next-generation practically applicable soft electronics.

Paxillin phase separation promotes focal adhesion assembly and integrin signaling.

Focal adhesions (FAs) are transmembrane protein assemblies mediating cell-matrix connection. Although protein liquid-liquid phase separation (LLPS) has been tied to the organization and dynamics of FAs, the underlying mechanisms remain unclear. Here, we experimentally tune the LLPS of PXN/Paxillin, an essential scaffold protein of FAs, by utilizing a light-inducible Cry2 system in different cell types. In addition to nucleating FA components, light-triggered PXN LLPS potently activates integrin signaling and subsequently accelerates cell spreading. In contrast to the homotypic interaction-driven LLPS of PXN in vitro, PXN condensates in cells are associated with the plasma membrane and modulated by actomyosin contraction and client proteins of FAs. Interestingly, non-specific weak intermolecular interactions synergize with specific molecular interactions to mediate the multicomponent condensation of PXN and are efficient in promoting FA assembly and integrin signaling. Thus, our data establish an active role of the PXN phase transition into a condensed membrane-associated compartment in promoting the assembly/maturation of FAs.

Roles of endothelial cell specific molecule­1 in tumor angiogenesis (Review).

Angiogenesis plays a crucial role in tumor growth and metastasis, and is heavily influenced by the tumor microenvironment (TME). Endothelial cell dysfunction is a key factor in tumor angiogenesis and is characterized by the aberrant expression of pro-angiogenic factors. Endothelial cell specific molecule-1 (ESM1), also known as endocan, is a marker of endothelial cell dysfunction. Although ESM1 is primarily expressed in normal endothelial cells, dysregulated ESM1 expression has been observed in human tumors and animal tumor models, and implicated in tumor growth, metastasis and angiogenesis. The precise role of ESM1 in tumor angiogenesis and its potential regulatory mechanisms are not yet conclusively defined. However, the aim of the present review was to explore the involvement of ESM1 in the process of tumor angiogenesis in the TME and the characteristics of neovascularization. In addition, the present review discusses the interaction between ESM1 and angiogenic factors, as well as the mechanisms through which ESM1 contributes to tumor angiogenesis. Furthermore, the reciprocal regulation between ESM1 and the TME is explored. Finally, the potential of targeting ESM1 as a therapeutic strategy for tumor angiogenesis is presented.

Relationship between readiness for interprofessional learning and academic self-efficacy among nursing students: a cross-sectional study.

BACKGROUND: Modern medicine emphasizes that medical professionals engage in interprofessional collaboration to better meet the diverse needs of patients from physical, psychological, and social perspectives. As nursing students are the future reserve of the clinical nursing workforce, nursing educators worldwide should pay close attention to nursing students' interprofessional learning attitudes and take responsibility for training qualified interprofessional nursing personnel. However, little is known about the relationship between nursing students' readiness for interprofessional learning and academic self-efficacy. Thus, this study aims to investigate the level of readiness for interprofessional learning and academic self-efficacy among nursing students, and to explore the relationship between the two. METHODS: A cross-sectional survey was conducted with a sample of 741 undergraduate nursing students pursuing four-year degrees from a school in Jinan, Shandong Province, China from November to December 2021. The social-demographic questionnaire, Readiness for Interprofessional Learning Scale, and Academic Self-efficacy Scale were used for data collection. Descriptive statistics used to analyze the data included: Cronbach's alpha, t-test, one-way ANOVA, Pearson's correlation, and multiple linear regression analysis. RESULTS: Readiness for interprofessional learning mean score was (3.91 ± 0.44) and mean academic self-efficacy was (3.47 ± 0.42). Significant differences were found in the research variables according to participants' sex, grade, choice of nursing profession, and frequency of communication with health-related major students in studies (p < 0.05, p < 0.001). Pearson correlation analysis showed that academic self-efficacy was positively related to readiness for interprofessional learning (r = 0.316, p < 0.01). The hierarchical regression analysis showed that academic self-efficacy was positively related to readiness for interprofessional learning (ß = 0.307, p < 0.001), The model explained 15.6% of the variance in readiness for interprofessional learning (F = 18.038, p < 0.001). CONCLUSIONS: Readiness for interprofessional learning and academic self-efficacy were in the middle level among nursing students. Moreover, there was a significant positive correlation between the two. Therefore, it is very important for nursing educators to improve nursing students' academic self-efficacy before improving their readiness for interprofessional learning.

An ULK1/2-PXN mechanotransduction pathway suppresses breast cancer cell migration.

The remodeling and stiffening of the extracellular matrix (ECM) is a well-recognized modulator of breast cancer progression. How changes in the mechanical properties of the ECM are converted into biochemical signals that direct tumor cell migration and metastasis remain poorly characterized. Here, we describe a new role for the autophagy-inducing serine/threonine kinases ULK1 and ULK2 in mechanotransduction. We show that ULK1/2 activity inhibits the assembly of actin stress fibers and focal adhesions (FAs) and as a consequence impedes cell contraction and migration, independent of its role in autophagy. Mechanistically, we identify PXN/paxillin, a key component of the mechanotransducing machinery, as a direct binding partner and substrate of ULK1/2. ULK-mediated phosphorylation of PXN at S32 and S119 weakens homotypic interactions and liquid-liquid phase separation of PXN, impairing FA assembly, which in turn alters the mechanical properties of breast cancer cells and their response to mechanical stimuli. ULK1/2 and the well-characterized PXN regulator, FAK/Src, have opposing functions on mechanotransduction and compete for phosphorylation of adjacent serine and tyrosine residues. Taken together, our study reveals ULK1/2 as important regulator of PXN-dependent mechanotransduction.

Comprehensive Profiling of Alternative Splicing and Alternative Polyadenylation during Fruit Ripening in Watermelon (Citrullus lanatus).

Fruit ripening is a highly complicated process that is accompanied by the formation of fruit quality. In recent years, a series of studies have demonstrated post-transcriptional control play important roles in fruit ripening and fruit quality formation. Till now, the post-transcriptional mechanisms for watermelon fruit ripening have not been comprehensively studied. In this study, we conducted PacBio single-molecule long-read sequencing to identify genome-wide alternative splicing (AS), alternative polyadenylation (APA) and long non-coding RNAs (lncRNAs) in watermelon fruit. In total, 6,921,295 error-corrected and mapped full-length non-chimeric (FLNC) reads were obtained. Notably, more than 42,285 distinct splicing isoforms were derived from 5,891,183 intron-containing full-length FLNC reads, including a large number of AS events associated with fruit ripening. In addition, we characterized 21,506 polyadenylation sites from 11,611 genes, 8703 of which have APA sites. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that fructose and mannose metabolism, starch and sucrose metabolism and carotenoid biosynthesis were both enriched in genes undergoing AS and APA. These results suggest that post-transcriptional regulation might potentially have a key role in regulation of fruit ripening in watermelon. Taken together, our comprehensive PacBio long-read sequencing results offer a valuable resource for watermelon research, and provide new insights into the molecular mechanisms underlying the complex regulatory networks of watermelon fruit ripening.

Effects of Social Support, Family Resilience, and Individual Resilience on Fear of Cancer Recurrence Among Persons With Breast Cancer: A Cross-Sectional Study.

BACKGROUND: There is limited research exploring the psychological and social predictors of fear of cancer recurrence (FCR). OBJECTIVE: This study tested the effects of social support, family resilience, and individual resilience on FCR among persons with breast cancer. METHODS: A convenience sampling method was used to select 214 participants from March to August 2021 in 1 tertiary hospital in Jinan, China. Data were collected using self-administered questionnaires. Path analysis was adopted to explore the effects of social support, family resilience, and individual resilience on FCR. RESULTS: Findings showed that 94.6% of the participants reached a clinical level of FCR. Social support (ß = -.75, p < .01) and individual resilience (ß = -.32, p < .01) negatively and directly impacted FCR. Family resilience indirectly impacted FCR through individual resilience (ß = -.22, 95% confidence interval (CI): -.34 to -.08). Social support indirectly impacted FCR through family resilience and individual resilience (ß = -.15, 95% CI: -.23 to -.06). CONCLUSIONS: Persons with breast cancer experienced a high level of FCR. Individual resilience was a mediator between family resilience and FCR. Resilience (individual resilience and family resilience) partially mediated the effects of social support on FCR. The findings indicate that measures focused on improving individual resilience, family resilience, and social support should be considered by nurses, which are helpful for easing FCR.

The Mediating Role of Job Stress Between Organizational Climate and Work Alienation Among Nurses in Emergency Departments: A Cross-sectional Study.

BACKGROUND: Nurses suffer a certain degree of work alienation (a psychological state in which employees feel separated from their jobs because the jobs do not meet the needs of employees or do not match their expectations). It is necessary to identify predictors of work alienation and find effective interventions. OBJECTIVE: To explore the influence of organizational climate and job stress on work alienation among nurses in emergency departments. METHODS: This was a cross-sectional study conducted from June to August 2022. A convenience sampling method was adopted to invite 342 nurses from emergency departments in 12 tertiary public hospitals in 4 cities in China. Data were collected using self-reported questionnaires on organizational climate, job stress, and work alienation. Path analysis implemented by IBM AMOS 21.0 was used to explore the associations among organizational climate, job stress, and work alienation. RESULTS: Job stress can positively affect work alienation among nurses in emergency departments (ß = 0.44, P < .01). Organizational climate can directly and negatively affect work alienation (ß = -0.33, P < .01); it can also negatively and indirectly affect work alienation through job stress (ß = -0.20, 95% confidence interval: -0.252 to -0.146). CONCLUSIONS: Job stress partially mediated the effect of organizational climate on work alienation among nurses in emergency departments. The findings provided a valuable perspective on predictors of work alienation among emergency department nurses.

RING finger ubiquitin E3 ligase CsCHYR1 targets CsATAF1 for degradation to modulate the drought stress response of cucumber through the ABA-dependent pathway.

CsCHYR1 (CHY ZINC-FINGER AND RING PROTEIN1) encodes a RING (Really Interesting New Gene) finger E3 ubiquitin ligase involved in ubiquitin-mediated protein degradation and plays an important role for cucumber to resist drought stress. Here, we obtain one of the candidate proteins CsCHYR1 that probably interacts with CsATAF1 by yeast-two hybrid screening. Subsequently, it is verified that CsCHYR1 interacts with CsATAF1 and has self-ubiquitination activity. When the cysteine residue at 180 in the RING domain of CsCHYR1 is replaced by serine or alanine, ubiquitin could not be transported from E2 to the substrate. CsCHYR1 ubiquitinates CsATAF1 and affects the stability of CsATAF1 when plants are subjected to drought stress. The expression level of CsCHYR1 is increased by 4-fold after ABA treatment at 9 h. The Atchyr1 mutants perform an ABA-hyposensitive phenotype and have a lower survival rate than Col-0 and CsCHYR1 Atchyr1 lines. In addition, CsCHYR1 interacts with CsSnRK2.6. Therefore, our study reveals a CsSnRK2.6-CsCHYR1-CsATAF1 complex to promote the drought stress response by decreasing CsATAF1 protein accumulation and inducing stomatal closure. Those findings provide new ideas for cucumber germplasm innovation from the perspective of biochemistry and molecular biology.

Comparison of Cold-Sprayed Coatings of Copper-Based Composite Deposited on AZ31B Magnesium Alloy and 6061 T6 Aluminum Alloy Substrates.

Copper-coated graphite and copper mixture powders were deposited on AZ31B magnesium alloy and 6061 T6 aluminum alloy substrates under different process parameters by a solid-state cold spray technique. The microstructure of the copper-coated graphite and copper composite coatings was visually examined using photographs taken with an optical microscope and a scanning electron microscope. The surface roughness of the coatings was investigated with a 3D profilometer. The thickness of the coatings was determined through the analysis of the microstructure images, while the adhesion of the coatings was characterized using the scratch test method. The results indicate that the surface roughness of the coatings sprayed on the two different substrates gradually decreases as gas temperature and gas pressure increase. Additionally, the thickness and adhesion of the coatings deposited on the two different substrates both increase with an increase in gas temperature and gas pressure. Comparing the surface roughness, thickness, and adhesion of the coatings deposited on the two different substrates, the surface roughness and adhesion of the coatings on the soft substrate are greater than those of the coatings on the hard substrate, while the thickness of the coatings is not obviously affected by the hardness of the substrate. Furthermore, it is noteworthy that the surface roughness, thickness, and adhesion of the copper-coated graphite and copper composite coatings sprayed on the two different substrates exhibit a distinct linear relationship with particle velocity.

Teacher stress among public primary and secondary schoolteachers in Datong, a city of Shanxi Province, China: association between teacher stress and standardized workload.

OBJECTIVES: The policy of the standardized workload has been implemented among primary and secondary schoolteachers in Shanxi Province. The aim of this cross-sectional cohort study is to assess teacher stress among primary and secondary schoolteachers in Datong, a city of Shanxi Province and the association between teacher stress and the quantified workload. MATERIAL AND METHODS: Three hundred and fifty schoolteachers in 10 public primary schools, 187 schoolteachers in 6 secondary schools and 268 non-teachers in 21 education institutes were recruited. A single-item rating assessment of work-related stress was completed by using the Exposure to Job Stress measure with modification. The quantified workload included class size, teaching hours, and subjects. Descriptive and logistic regression analyses were carried out. RESULTS: In 805 participants, the pro- portion of primary and secondary schoolteachers with moderate stress was significantly greater. The results of Spearman's correlation and logistic regression analyses showed that the occupations of the primary and secondary schoolteachers had higher stress risk. Further, the stratified results showed that among the primary schoolteachers, the independent stress risk factor was larger class size; while among the secondary schoolteachers, the stress associated factor was more weekly teaching hours. CONCLUSIONS: After standardization of the workload, there remain higher levels of work stress among primary and secondary schoolteachers. Notwithstanding, the stress state in teachers is manageable and they may be faced with controllable stressors. Int J Occup Med Environ Health. 2023;36(2):161-76.

Phylogenetic and Evolutionary Comparison of Mitogenomes Reveal Adaptive Radiation of Lampriform Fishes.

Lampriform fishes (Lampriformes), which primarily inhabit deep-sea environments, are large marine fishes varying from the whole-body endothermic opah to the world's longest bony fish-giant oarfish, with species morphologies varying from long and thin to deep and compressed, making them an ideal model for studying the adaptive radiation of teleost fishes. Moreover, this group is important from a phylogenetic perspective owing to their ancient origins among teleosts. However, knowledge about the group is limited, which is, at least partially, due to the dearth of recorded molecular data. This study is the first to analyze the mitochondrial genomes of three lampriform species (Lampris incognitus, Trachipterus ishikawae, and Regalecus russelii) and infer a time-calibrated phylogeny, including 68 species among 29 orders. Our phylomitogenomic analyses support the classification of Lampriformes as monophyletic and sister to Acanthopterygii; hence, addressing the longstanding controversy regarding the phylogenetic status of Lampriformes among teleosts. Comparative mitogenomic analyses indicate that tRNA losses existed in at least five Lampriformes species, which may reveal the mitogenomic structure variation associated with adaptive radiation. However, codon usage in Lampriformes did not change significantly, and it is hypothesized that the nucleus transported the corresponding tRNA, which led to function substitutions. The positive selection analysis revealed that atp8 and cox3 were positively selected in opah, which might have co-evolved with the endothermic trait. This study provides important insights into the systematic taxonomy and adaptive evolution studies of Lampriformes species.

ClSnRK2.3 negatively regulates watermelon fruit ripening and sugar accumulation.

Watermelon (Citrullus lanatus) as non-climacteric fruit is domesticated from the ancestors with inedible fruits. We previously revealed that the abscisic acid (ABA) signaling pathway gene ClSnRK2.3 might influence watermelon fruit ripening. However, the molecular mechanisms are unclear. Here, we found that the selective variation of ClSnRK2.3 resulted in lower promoter activity and gene expression level in cultivated watermelons than ancestors, which indicated ClSnRK2.3 might be a negative regulator in fruit ripening. Overexpression (OE) of ClSnRK2.3 significantly delayed watermelon fruit ripening and suppressed the accumulation of sucrose, ABA and gibberellin GA4 . Furthermore, we determined that the pyrophosphate-dependent phosphofructokinase (ClPFP1) in sugar metabolism pathway and GA biosynthesis enzyme GA20 oxidase (ClGA20ox) could be phosphorylated by ClSnRK2.3 and thereby resulting in accelerated protein degradation in OE lines and finally led to low levels of sucrose and GA4 . Besides that, ClSnRK2.3 phosphorylated homeodomain-leucine zipper protein (ClHAT1) and protected it from degradation to suppress the expression of the ABA biosynthesis gene 9'-cis-epoxycarotenoid dioxygenase 3 (ClNCED3). These results indicated that ClSnRK2.3 negatively regulated watermelon fruit ripening by manipulating the biosynthesis of sucrose, ABA and GA4 . Altogether, these findings revealed a novel regulatory mechanism in non-climacteric fruit development and ripening.

Physicochemical parameters and nutritional profile of back and abdomen muscle of fresh golden pompano (Trachinotus ovatus) and hybrid grouper (Epinephelus lanceolatus × Epinephelus fuscoguttatus).

Golden pompano (Trachinotus ovatus) and hybrid grouper (Epinephelus lanceolatus × Epinephelus fuscoguttatus) has widely been distributed in China and Southeast Asian countries with great commercial importance. In this study, the nutritional profiles, chemical and physical parameters of back and abdomen muscles were determined. Significantly different (p < .05) proximate compositions were found in two fish muscles. The contents of water-soluble protein, salt-soluble protein, and non-nitrogenous protein were higher in the golden pompano while salt-insoluble proteins were higher in the hybrid grouper. The main minerals found were K (3700.56-4495.57 µg/g) followed by P > Na > Mg > and Ca, respectively. Fatty acids contents consisted of polyunsaturated fatty acids ranging from 29.40% to 43.09% and saturated fatty acids 28.33% to 39.61%. The muscles were rich in n-3 PUFAs with n-6/n-3 ratio of 1.36%-2.96% in the back and abdomen. On the other hand, total amino acid and non-essential amino acid contents were found higher in the hybrid grouper while essential amino acid and delicious amino acid contents were higher in the golden pompano. Glutamic acid was the most predominant amino acid. The amino acid scores (AAS) of six amino acids were close to 1.00, whereas lysine showed the highest AAS while tryptophan was the most limited essential amino acid in all muscles, respectively. These results indicated golden pompano and hybrid grouper exhibited a varied nutritional composition and offered a good nutritional profile.

Impact of high-speed rail on tourism in China.

The "time-space compression" effect of high-speed rail (HSR) has effectively improved the accessibility of the cities and has had a profound impact on tourism. This study explores the impact of HSR on tourism development in cities along HSR lines from the perspective of transfer of transport advantages, then evaluates the impact of HSR on tourism development using panel data of 286 cities in China from 2005 to 2013 by the difference-in-differences (DID) method. The empirical results show that the opening of HSR has significantly increased the tourism revenue and tourist arrivals. These results are still holds after considering endogenous HSR lines placement, and by various robustness checks. Further analysis of nodal effect shows that node cities experienced greater growth in tourism revenue than non-node cities. The analysis of mechanism found that tourism development in node cities relied on hotel industry, while tourism development in non-node cities relied on scenic spots industry. The findings of this study validate the role of HSR as a catalyst for urban tourism development, and reveal the comparative advantages of tourism in different cities under the influence of HSR. This study has important reference value for the development of tourism industry policies in cities along and around HSR lines.

Identification of psychological stressors in cancer patients based on a computer decision support nursing system.

OBJECTIVE: We aim to improve the decision-making process of nursing evaluation, and the purpose of this paper was to introduce nursing outcome classifications based on standardized nursing language, as well as build a comprehensive nursing evaluation decision-making system model based on an artificial neural network and fuzzy comprehensive evaluations. METHODS: Based on the principle and method of the decision support system (DSS), this paper proposed a framework of DSS and developed an intelligent nursing decision support system which integrates expert systems, data, models and knowledge. RESULTS: Taking cancer patients as examples, based on the analysis and comparison of cancer stressors and their frequency of occurrence, this paper found that the 5 major factors for cancer patients' stress events were lack of privacy, attitude of the medical workers, unfamiliar medical workers and uncomfortable temperature in wards. In addition, through the single factor analysis of the stressors, it was found that "the impact of hospitalization on individuals and their families", "the professional level and service attitude of medical workers", and "partial loss of free social contact in the hospital" were all positively correlated with stress level. The degree of cancer patients' participation in treatment decision-making was lower than the expectation of the patients. There was a statistically significant difference between the actual participation and the anticipated participation of cancer patients in nursing decision-making (P < 0.0001). In addition, the system helped patients adapt to the hospital environment as quickly as possible, so that they could feel comfortable in the hospital environment, as well as a relaxed and pleasant with the humanistic environment. CONCLUSION: Cancer patients have a variety of stressors, and the pressure is high. Our computer decision support nursing system assisted nurses to help patients to take positive coping measures to relieve pressure as soon as possible, so as to improve their quality of life.

A zinc finger protein SlSZP1 protects SlSTOP1 from SlRAE1-mediated degradation to modulate aluminum resistance.

In acidic soils, aluminum (Al) toxicity is the main factor inhibiting plant root development and reducing crops yield. STOP1 (SENSITIVE TO PROTON RHIZOTOXICITY 1) was a critical factor in detoxifying Al stress. Under Al stress, STOP1 expression was not induced, although STOP1 protein accumulated, even in the presence of RAE1 (STOP1 DEGRADATION E3-LIGASE). How the Al stress triggers and stabilises the accumulation of STOP1 is still unknown. Here, we characterised SlSTOP1-interacting zinc finger protein (SlSZP1) using a yeast-two-hybrid screening, and generated slstop1, slszp1 and slstop1/slszp1 knockout mutants using clustered regularly interspaced short palindromic repeats (CRISPR) in tomato. SlSZP1 is induced by Al stress but it is not regulated by SlSTOP1. The slstop1, slszp1 and slstop1/slszp1 knockout mutants exhibited hypersensitivity to Al stress. The expression of SlSTOP1-targeted genes, such as SlRAE1 and SlASR2 (ALUMINUM SENSITIVE), was inhibited in both slstop1 and slszp1 mutants, but not directly regulated by SlSZP1. Furthermore, the degradation of SlSTOP1 by SlRAE1 was prevented by SlSZP1. Al stress increased the accumulation of SlSTOP1 in wild-type (WT) but not in slszp1 mutants. The overexpression of either SlSTOP1 or SlSZP1 did not enhance plant Al resistance. Altogether, our results show that SlSZP1 is an important factor for protecting SlSTOP1 from SlRAE1-mediated degradation.

Natural variation in the NAC transcription factor NONRIPENING contributes to melon fruit ripening.

The NAC transcription factor NONRIPENING (NOR) is a master regulator of climacteric fruit ripening. Melon (Cucumis melo L.) has climacteric and non-climacteric fruit ripening varieties and is an ideal model to study fruit ripening. Two natural CmNAC-NOR variants, the climacteric haplotype CmNAC-NORS,N and the non-climacteric haplotype CmNAC-NORA,S , have effects on fruit ripening; however, their regulatory mechanisms have not been elucidated. Here, we report that a natural mutation in the transcriptional activation domain of CmNAC-NORS,N contributes to climacteric melon fruit ripening. CmNAC-NOR knockout in the climacteric-type melon cultivar "BYJH" completely inhibited fruit ripening, while ripening was delayed by 5-8 d in heterozygous cmnac-nor mutant fruits. CmNAC-NOR directly activated carotenoid, ethylene, and abscisic acid biosynthetic genes to promote fruit coloration and ripening. Furthermore, CmNAC-NOR mediated the transcription of the "CmNAC-NOR-CmNAC73-CmCWINV2" module to enhance flesh sweetness. The transcriptional activation activity of the climacteric haplotype CmNAC-NORS,N on these target genes was significantly higher than that of the non-climacteric haplotype CmNAC-NORA,S . Moreover, CmNAC-NORS,N complementation fully rescued the non-ripening phenotype of the tomato (Solanum lycopersicum) cr-nor mutant, while CmNAC-NORA,S did not. Our results provide insight into the molecular mechanism of climacteric and non-climacteric fruit ripening in melon.