Multi-Omics Analysis Reveals Intricate Gene Networks Involved in Female Development in Melon.

Sexual differentiation is an important developmental phenomenon in cucurbits that directly affects fruit yield. The natural existence of multiple flower types in melon offers an inclusive structure for studying the molecular basis of sexual differentiation. The current study aimed to identify and characterize the molecular network involved in sex determination and female development in melon. Male and female pools separated by the F2 segregated generation were used for sequencing. The comparative multi-omics data revealed 551 DAPs and 594 DEGs involved in multiple pathways of melon growth and development, and based on functional annotation and enrichment analysis, we summarized four biological process modules, including ethylene biosynthesis, flower organ development, plant hormone signaling, and ubiquitinated protein metabolism, that are related to female development. Furthermore, the detailed analysis of the female developmental regulatory pathway model of ethylene biosynthesis, signal transduction, and target gene regulation identified some important candidates that might have a crucial role in female development. Two CMTs ((cytosine-5)-methyltransferase), one AdoHS (adenosylhomocysteinase), four ACSs (1-aminocyclopropane-1-carboxylic acid synthase), three ACOs (ACC oxidase), two ARFs (auxin response factor), four ARPs (auxin-responsive protein), and six ERFs (Ethylene responsive factor) were identified based on various female developmental regulatory models. Our data offer new and valuable insights into female development and hold the potential to offer a deeper comprehension of sex differentiation mechanisms in melon.

How teacher-student closeness and conflict contributes to mathematical problem solving in Chinese adolescents: a multilevel moderated mediation model of self-efficacy and school climate.

The current study investigated how and when two different aspects of teacher-student relationship (TSR; closeness and conflict) influence students' mathematical problem solving ability. Participants were 9163 eighth-grade Chinese adolescents (53.5% male) nested in 908 schools, who took part in a standard mathematics assessment and survey using student questionnaires that were all developed by the Collaborative Innovation Center of Assessment toward Basic Education Quality (CICA-BEQ) in China in 2015. The results indicated that (a) after controlling the factors of gender and SES, teacher-student closeness had a significant and positive effect on mathematical problem solving, while teacher-student conflict did not, (b) the mediating role of mathematical self-efficacy in the relationships of TSRs and mathematical problem solving was confirmed, and (c) school climate negatively moderated the indirect relationships between TSRs and mathematical problem solving.

Comparative Analysis of Calcium-Dependent Protein Kinase in Cucurbitaceae and Expression Studies in Watermelon.

Both the calcium-dependent protein kinases (CDPKs) and CDPK-related kinases (CRKs) play numerous roles in plant growth, development, and stress response. Despite genome-wide identification of both families in Cucumis, comparative evolutionary and functional analysis of both CDPKs and CRKs in Cucurbitaceae remain unclear. In this study, we identified 128 CDPK and 56 CRK genes in total in six Cucurbitaceae species (C. lanatus, C. sativus, C. moschata, C. maxima, C. pepo, and L. siceraria). Dot plot analysis indicated that self-duplication of conserved domains contributed to the structural variations of two CDPKs (CpCDPK19 and CpCDPK27) in C. pepo. Using watermelon genome as reference, an integrated map containing 25 loci (16 CDPK and nine CRK loci) was obtained, 16 of which (12 CDPK and four CRK) were shared by all seven Cucurbitaceae species. Combined with exon-intron organizations, topological analyses indicated an ancient origination of groups CDPK IV and CRK. Moreover, the evolutionary scenario of seven modern Cucurbitaceae species could also be reflected on the phylogenetic trees. Expression patterns of ClCDPKs and ClCRKs were studied under different abiotic stresses. Some valuable genes were uncovered for future gene function exploration. For instance, both ClCDPK6 and its ortholog CsCDPK14 in cucumber could be induced by salinity, while ClCDPK6 and ClCDPK16, as well as their orthologs in Cucumis, maintained high expression levels in male flowers. Collectively, these results provide insights into the evolutionary history of two gene families in Cucurbitaceae, and indicate a subset of candidate genes for functional characterizations in the future.

Glutathione-dependent induction of local and systemic defense against oxidative stress by exogenous melatonin in cucumber (Cucumis sativus L.).

Melatonin is involved in defending against oxidative stress caused by various environmental stresses in plants. In this study, the roles of exogenous melatonin in regulating local and systemic defense against photooxidative stress in cucumber (Cucumis sativus) and the involvement of redox signaling were examined. Foliar or rhizospheric treatment with melatonin enhanced tolerance to photooxidative stress in both melatonin-treated leaves and untreated systemic leaves. Increased melatonin levels are capable of increasing glutathione (reduced glutathione [GSH]) redox status. Application of H2 O2 and GSH also induced tolerance to photooxidative stress, while inhibition of H2 O2 accumulation and GSH synthesis compromised melatonin-induced local and systemic tolerance to photooxidative stress. H2 O2 treatment increased the GSH/oxidized glutathione (GSSG) ratio, while inhibition of H2 O2 accumulation prevented a melatonin-induced increase in the GSH/GSSG ratio. Additionally, inhibition of GSH synthesis blocked H2 O2 -induced photooxidative stress tolerance, whereas scavenging or inhibition of H2 O2 production attenuated but did not abolish GSH-induced tolerance to photooxidative stress. These results strongly suggest that exogenous melatonin is capable of inducing both local and systemic defense against photooxidative stress and melatonin-enhanced GSH/GSSG ratio in a H2 O2 -dependent manner is critical in the induction of tolerance.

Multiple facial basal cell carcinomas in xeroderma pigmentosum treated with topical imiquimod 5% cream.

Xeroderma pigmentosum (XP) is an autosomal recessive disease characterized by solar sensitivity, photophobia, early onset of freckling, and solar-induced cutaneous neoplastic changes. Management of patients with XP is a therapeutic challenge as they usually develop multiple cutaneous malignancies, making surgical therapy difficult, and continue to form skin malignancies at a high rate. We describe a 30-year-old Chinese man with XP who had been previously treated with excision and dermatoplasty. Upon recurrence of multiple superficial, ulcerative, and pigmented lesions, imiquimod 5% cream was recommended for 4 months. His multiple facial lesions demonstrated an excellent response to topical imiquimod 5% cream with minor side effects. This favorable response indicates that topical application of imiquimod 5% cream is an effective means of treating multiple basal cell carcinomas in XP.

Cancer metabolism and carcinogenesis.

Metabolic reprogramming is an emerging hallmark of cancer cells, enabling them to meet increased nutrient and energy demands while withstanding the challenging microenvironment. Cancer cells can switch their metabolic pathways, allowing them to adapt to different microenvironments and therapeutic interventions. This refers to metabolic heterogeneity, in which different cell populations use different metabolic pathways to sustain their survival and proliferation and impact their response to conventional cancer therapies. Thus, targeting cancer metabolic heterogeneity represents an innovative therapeutic avenue with the potential to overcome treatment resistance and improve therapeutic outcomes. This review discusses the metabolic patterns of different cancer cell populations and developmental stages, summarizes the molecular mechanisms involved in the intricate interactions within cancer metabolism, and highlights the clinical potential of targeting metabolic vulnerabilities as a promising therapeutic regimen. We aim to unravel the complex of metabolic characteristics and develop personalized treatment approaches to address distinct metabolic traits, ultimately enhancing patient outcomes.

Epidemiology of the non-head and neck sebaceous carcinoma and implications for distant metastasis screening.

Introduction: Extraocular sebaceous carcinoma (SC), particularly those outside the head and neck region, is rare and not well-described. Purpose: This study aimed to explore the epidemiology and identify the prognostic factors of non-head and neck SC, describe the possible relevant factors of distant metastasis, and provide implications for distant metastasis screening. Methods: Data from the 17 registries in the Surveillance, Epidemiology, and End Results database were retrospectively collected for patients with SC outside the head and neck from 2000 through 2020. Overall survival (OS) and disease-specific survival (DSS) were the primary endpoints. Survival analysis was conducted through Kaplan-Meier curves, and multivariate analysis was carried out using Cox proportional hazard models. Results: A total of 1,237 patients with SC outside the head and neck were identified. The mean age at diagnosis of the entire patient cohort was 67.7 years (30 to 90+ years), and the mean tumor size was 2.2 cm (0.1-16 cm). Patients with distant disease experienced the lowest OS (mean, 29.5 months) than those with localized disease and regional disease (p < 0.0001). Multivariate analysis revealed that age, tumor size, and stage were independent determinants of OS; age, stage, and primary site were independent determinants of DSS. Tumor grade and lymph node status had less prognostic value for survival. Undifferentiated tumors have a trend toward distant metastasis, especially those at the primary site of the trunk. Conclusion: The prognosis of the non-head and neck SC is excellent, while the survival of distant disease is very poor. Distant metastasis screening can be considered for undifferentiated tumors, especially those located in the trunk region with large tumor sizes.

Therapeutic Targeting of the GLS1-c-Myc Positive Feedback Loop Suppresses Glutaminolysis and Inhibits Progression of Head and Neck Cancer.

Head and neck squamous cell carcinoma (HNSCC) is addicted to glutaminolysis. Targeting this metabolic dependency has emerged as a potential therapeutic approach for HNSCC. Here, we conducted a bioinformatic analysis of the TCGA HNSCC cohort that revealed a robust correlation between expression of c-Myc and GLS1, which catalyzes the first step in glutaminolysis. Intriguingly, disruption of GLS1 signaling in HNSCC cells by genetic depletion or CB-839 treatment resulted in a reduction in c-Myc protein stability via a USP1-dependent ubiquitin-proteasome pathway. On the other hand, c-Myc directly binds to the promoter region of GLS1 and upregulates its transcription. Notably, the GLS1-c-Myc pathway enhanced ACC-dependent SLUG acetylation, prompting cancer cell invasion and metastasis. Thus, the GLS1-c-Myc axis emerged as a positive feedback loop critical for driving the aggressiveness of HNSCC. Therapeutically, combining CB-839 with the c-Myc inhibitor MYCi975 strongly suppressed GLS1-c-Myc signaling, resulting in a superior antitumor effect compared to either single agent in an orthotopic mouse model of HNSCC. These findings hold promise for the development of effective therapies for HNSCC patients, addressing an urgent need arising from the significant incidence and high metastatic rate of the disease.

Mutation p.Arg127Pro in the 1A Domain of KRT16 Causes Pachyonychia Congenita in Chinese Patient: A Case Report of PC Associated with Acral Melanoma.

Pachyonychia congenita (PC) is a group of rare hereditary disorders, characterised by hypertrophic nails and palmoplantar keratoderma (PPK), particularly localised to the pressure areas of the feet. At a molecular level, it is caused by mutations in genes encoding KRT6A, KRT6B, KRT6C, KRT16, or KRT17. To identify the underlying gene mutation in a Chinese family with PC presenting with disabling palmoplantar keratoderma and subsequent associated acral melanoma. Genomic DNA was extracted from peripheral blood samples of three available individuals in the Chinese family, which included the patient and his two unaffected sisters. The index patient presented with severe palmoplantar keratoderma as well as a newly diagnosed acral malignant melanoma (MM). Whole-exome sequencing (WES) was carried out with amplification of exon 1 of KRT16 by polymerase chain reaction (PCR). PCR products were then sequenced to identify potential mutations. We identified the proline substitution mutation p.Arg127Pro (c.380G>C) in our patient's 1A domain of KRT16. The same mutation was not found in his sisters or unrelated healthy controls. The mutation (p.Arg127Pro (c.380G>C)) in KRT16 has been reported in Dutch patients with PC. However, it is the first such report of a patient with a PC of Chinese origin. In addition, the acral MM occurred under the background of genetic PPK caused by KRT16 mutation in this patient.

Harnessing cancer stem cell-derived exosomes to improve cancer therapy.

Cancer stem cells (CSCs) are the key "seeds" for tumor initiation and development, metastasis, and recurrence. Because of the function of CSCs in tumor development and progression, research in this field has intensified and CSCs are viewed as a new therapeutic target. Exosomes carrying a wide range of DNA, RNA, lipids, metabolites, and cytosolic and cell-surface proteins are released outside of the originating cells through the fusion of multivesicular endosomes or multivesicular bodies with the plasma membrane. It has become evident that CSC-derived exosomes play a significant role in almost all "hallmarks" of cancer. For example, exosomes from CSCs can maintain a steady state of self-renewal in the tumor microenvironment and regulate microenvironmental cells or distant cells to help cancer cells escape immune surveillance and induce immune tolerance. However, the function and therapeutic value of CSC-derived exosomes and the underlying molecular mechanisms are still largely undefined. To provide an overview of the possible role of CSC-derived exosomes and targeting strategies, we summarize relevant research progress, highlight the potential impact of detecting or targeting CSC-derived exosomes on cancer treatment, and discuss opportunities and challenges based on our experience and insights in this research area. A more thorough understanding of the characteristics and function of CSC-derived exosomes may open new avenues to the development of new clinical diagnostic/prognostic tools and therapies to prevent tumor resistance and relapse.

Seasonal precipitation regulates magnitude and direction of the effect of nitrogen addition on net ecosystem CO2 exchange in saline-alkaline grassland of northern China.

Increased nitrogen (N) deposition and altered precipitation regimes have profound effects on carbon (C) flux in semi-arid grasslands. However, the interactive effects between N enrichment and precipitation alterations (both increasing and decreasing) on ecosystem CO2 fluxes and ecosystem resource use efficiency (water use efficiency (WUE) and carbon use efficiency (CUE)) remain unclear, particularly in saline-alkaline grasslands. A four-year (2018-2021) field manipulation experiment was conducted to investigate N enrichment and precipitation alterations (decreased and increased by 50 % of ambient precipitation) and their interactions on ecosystem CO2 fluxes (gross- ecosystem productivity (GEP), ecosystem respiration (ER), and net ecosystem CO2 exchange (NEE)), as well as their underlying regulatory mechanisms under severe salinity stress in northern China. Our results showed that N addition and precipitation alteration alone did not significantly affect the GEP, ER and NEE. While the interaction of N addition and increased precipitation over the four years significantly improved the mean GEP and NEE by 24.9 % and 15.9 %, respectively. The interactive effects of N addition and increased precipitation treatment significantly stimulated the mean value of WUE by 39.1 % compared with control, but had no significant effects on CUE over the four years. Based on the four-year experiment, the magnitude and direction of the effects of N addition on the NEE were related to seasonal precipitation. Nitrogen addition increased the NEE under increased precipitation and decreased it during extreme drought. Soil salinization (pH and base cations) could directly or indirectly affect GEP and NEE via plants productivity, plant communities, as well as ecosystem resource use efficiency (WUE and CUE) based on structural equation model. Our results address lacking investigations of ecosystem C flux in saline-alkaline grasslands, and highlight that precipitation regulates the magnitude and direction of N addition on NEE in saline-alkaline grasslands.

Efficient Drug Delivery of Ti3C2Tx MXenes for Synergistic Treatment of Human Hypopharyngeal Squamous Cell Carcinoma.

Ti3C2Tx MXene is a versatile two-dimensional material that exhibits exceptional properties, such as an abundance of surface functional groups that facilitate modifications. Additionally, Ti3C2Tx MXene possesses remarkable photothermal effects. In this study, ultrathin Ti3C2Tx nanosheets with dimensions (∼200 nm) suitable for biological applications were prepared by ultrasonication of larger pieces of Ti3C2Tx MXene with a cell pulverizer operating at a specific power. The ultrathin nanosheets exhibited a significant photothermal conversion efficiency (47.1%) under an 808 nm infrared laser irradiation. In addition, they showed an excellent mass extinction coefficient of 15.7 L g-1 cm-1. By exploiting the intermolecular force between these ultrathin nanosheets and doxorubicin (DOX), a drug loading efficiency of 72.8% was achieved. Through layer-by-layer surface modification of a sulfhydryl-modified polymethacrylic acid (PMAsh) shell and a transferrin (Tf) layer with targeting function, a multifunctional nanomedicine platform (Ti3C2Tx-DOX-PMAsh-Tf) was constructed. Experiments executed in vitro with cells and in vivo to inhibit tumors manifested that Ti3C2Tx is biocompatible. Furthermore, the results showed that the drug release behavior of Ti3C2Tx-DOX-PMAsh-Tf is responsive to glutathione (GSH) stimulation. The synergistic treatment of photothermal therapy and the anticancer drug DOX effectively achieved the inhibition of human hypopharyngeal squamous cell carcinoma.

Higher N Addition and Mowing Interactively Improved Net Primary Productivity by Stimulating Gross Nitrification in a Temperate Steppe of Northern China.

Anthropogenic disturbance, such as nitrogen (N) fertilization and mowing, is constantly changing the function and structure of grassland ecosystems during past years and will continue to affect the sustainability of arid and semiarid grassland in the future. However, how and whether the different N addition levels and the frequency of N addition, as well as the occurrence of mowing, affect the key processes of N cycling is still unclear. We designed a field experiment with five levels of N addition (0, 2, 10, 20, and 50 g N m-2 yr-1), two types of N addition frequencies (twice a year added in June/November and monthly addition), and mowing treatment in a typical grassland of northern China. The results showed that higher N addition and mowing interactively improved net primary productivity (NPP), including aboveground and belowground biomass, while different N addition frequency had no significant effects on NPP. Different N addition levels significantly improved gross ammonification (GA) and nitrification (GN) rates, which positively correlated to aboveground net primary productivity (ANPP). However, the effect of N addition frequency was differentiated with N addition levels, the highest N addition level (50 g N m-2 yr-1) with lower frequency (twice a year) significantly increased GA and GN rates. Mowing significantly increased the GA rate but decreased the GN rate both under the highest N addition level (50 g N m-2 yr-1) and lower N addition frequency (twice a year), which could improve N turnover by stimulating plant and microbial activity. However, a long-term study of the effects of N enrichment and mowing on N turnover will be needed for understanding the mechanisms by which nutrient cycling occurs in typical grassland ecosystems under global change scenarios.

N4-acetylcytidine-dependent GLMP mRNA stabilization by NAT10 promotes head and neck squamous cell carcinoma metastasis and remodels tumor microenvironment through MAPK/ERK signaling pathway.

N4-acetylcytidine (ac4C) is a post-transcriptional RNA modification that regulates in various important biological processes. However, its role in human cancer, especially lymph node metastasis, remains largely unknown. Here, we demonstrated N-Acetyltransferase 10 (NAT10), as the only known "writer" of ac4C mRNA modification, was highly expressed in head and neck squamous cell carcinoma (HNSCC) patients with lymph node metastasis. High NAT10 levels in the lymph nodes of patients with HNSCC patients are a predictor of poor overall survival. Moreover, we found that high expression of NAT10 was positively upregulated by Nuclear Respiratory Factor 1 (NRF1) transcription factor. Gain- and loss-of-function experiments displayed that NAT10 promoted cell metastasis in mice. Mechanistically, NAT10 induced ac4C modification of Glycosylated Lysosomal Membrane Protein (GLMP) and stabilized its mRNA, which triggered the activation of the MAPK/ERK signaling pathway. Finally, the NAT10-specific inhibitor, remodelin, could inhibit HNSCC tumorigenesis in a 4-Nitroquinoline 1-oxide (4NQO)-induced murine tumor model and remodel the tumor microenvironment, including angiogenesis, CD8+ T cells and Treg recruitment. These results demonstrate that NAT10 promotes lymph node metastasis in HNSCC via ac4C-dependent stabilization of the GLMP transcript, providing a potential epitranscriptomic-targeted therapeutic strategy for HNSCC.

Whole-transcriptome analyses identify key differentially expressed mRNAs, lncRNAs, and miRNAs associated with male sterility in watermelon.

Male sterility is a valuable trait for watermelon breeding, as watermelon hybrids exhibit obvious heterosis. However, the underlying regulatory mechanism is still largely unknown, especially regarding the related non-coding genes. In the present study, approximately 1035 differentially expressed genes (DEGs), as well as 80 DE-lncRNAs and 10 DE-miRNAs, were identified, with the overwhelming majority down-regulated in male-sterile floral buds. Enrichment analyses revealed that the general phenylpropanoid pathway as well as its related metabolisms was predicted to be altered in a mutant compared to its fertile progenitor. Meanwhile, the conserved genetic pathway DYT1-TDF1-AMS-MS188-MS1, as well as the causal gene ClAMT1 for the male-sterile mutant Se18, was substantially disrupted during male reproductive development. In addition, some targets of the key regulators AMS and MS188 in tapetum development were also down-regulated at a transcriptional level, such as ABCG26 (Cla004479), ACOS5 (Cla022956), CYP703A2 (Cla021151), PKSA (Cla021099), and TKPR1 (Cla002563). Considering lncRNAs may act as functional endogenous target mimics of miRNAs, competitive endogenous RNA networks were subsequently constructed, with the most complex one containing three DE-miRNAs, two DE-lncRNAs, and 21 DEGs. Collectively, these findings not only contribute to a better understanding of genetic regulatory networks underlying male sterility in watermelon, but also provide valuable candidates for future research.

Exosomes Derived from Adipose Mesenchymal Stem Cells Carrying miRNA-22-3p Promote Schwann Cells Proliferation and Migration through Downregulation of PTEN.

Peripheral nerve injury (PNI) is often resulting from trauma, which leads to severe and permanently disability. Schwann cells are critical for facilitating the regeneration process after PNI. Adipose-derived mesenchymal stem cells (ADSCs) exosomes have been used as a novel treatment for peripheral nerve injury. However, the underlying mechanism remains unclear. In this study, we isolated ADSCs and extracted exosomes, which were verified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot (WB). Cocultured with Dorsal Root Ganglion (DRG) and Schwann cells (SCs) to evaluate the effect of exosomes on the growth of DRG axons by immunofluorescence, and the proliferation and migration of SCs by CCK8 and Transwell assays, respectively. Through exosomal miRNA sequencing and bioinformatic analysis, the related miRNAs and target gene were predicted and identified by dual luciferase assay. Related miRNAs were overexpressed and inhibited, respectively, to clarify their effects; the downstream pathway through the target gene was determined by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and WB. Results found that ADSC-exosomes could promote the proliferation and migration of SCs and the growth of DRG axons, respectively. Exosomal miRNA-22-3p from ADSCs directly inhibited the expression of Phosphatase and Tensin Homolog deleted on Chromosome 10 (PTEN), activated phosphorylation of the AKT/mTOR axis, and enhanced SCs proliferation and migration. In conclusion, our findings suggest that ADSC-exosomes could promote SCs function through exosomal miRNA-22-3p, which could be used as a therapeutic target for peripheral nerve injury.

The HD-ZIP Gene Family in Watermelon: Genome-Wide Identification and Expression Analysis under Abiotic Stresses.

Homeodomain-leucine zipper (HD-ZIP) transcription factors are one of the plant-specific gene families involved in plant growth and response to adverse environmental conditions. However, little information is available on the HD-ZIP gene family in watermelon. In this study, forty ClHDZs were systemically identified in the watermelon genome, which were subsequently divided into four distinctive subfamilies (I-IV) based on the phylogenetic topology. HD-ZIP members in the same subfamily generally shared similar gene structures and conserved motifs. Syntenic analyses revealed that segmental duplications mainly contributed to the expansion of the watermelon HD-ZIP family, especially in subfamilies I and IV. HD-ZIP III was considered the most conserved subfamily during the evolutionary history. Moreover, expression profiling together with stress-related cis-elements in the promoter region unfolded the divergent transcriptional accumulation patterns under abiotic stresses. The majority (13/23) of ClHDZs in subfamilies I and II were downregulated under the drought condition, e.g., ClHDZ4, ClHDZ13, ClHDZ18, ClHDZ19, ClHDZ20, and ClHDZ35. On the contrary, most HD-ZIP genes were induced by cold and salt stimuli with few exceptions, such as ClHDZ3 and ClHDZ23 under cold stress and ClHDZ14 and ClHDZ15 under the salt condition. Notably, the gene ClHDZ14 was predominantly downregulated by three stresses whereas ClHDZ1 was upregulated, suggesting their possible core roles in response to these abiotic stimuli. Collectively, our findings provide promising candidates for the further genetic improvement of abiotic stress tolerance in watermelon.

[Intra-annual radial growth of Abies georgei and Larix potaninii and its responses to environmental factors in the Baima Snow Mountain, Northwest Yunnan, China.] / æ»‡è¥¿åŒ—ç™½é©¬é›ªå±±é•¿è‹žå†·æ‰å’Œå¤§æžœçº¢æ‰å¹´å† å¾„å‘ç”Ÿé•¿åŠ¨æ€åŠå ¶å¯¹çŽ¯å¢ƒå› å­çš„å“åº”.

Using high-resolution dendrometers, we monitored the intra-annual stem radial variations of Abies georgei and Larix potaninii in the subalpine coniferous forest in Baima Snow Mountain, Northwest Yunnan Province. The seasonal dynamics of stem radial growth of both species and their responses to environmental factors were analyzed. The results showed that the stem radial growth of A. georgei and L. potaninii mainly occurred during April to August, with the maximum growth rate in June. Compared with A. georgei, L. potaninii showed an earlier start but later cessation of stem radial growth, resulting in longer growth duration. Annual radial growth and maximum radial growth rates of L. potaninii were slightly higher than those of A. georgei. Daily growth rate of A. georgei was positively correlated with precipitation, but negatively correlated with vapor pressure deficit and air temperature. Daily growth rate of L. potaninii was positively correlated with precipitation, but negatively correlated with soil volume water content and vapor pressure deficit. Radial growth of A. georgei and L. potaninii was limited by water availability, with L. potaninii being more sensitive to moisture. Under the background of global warming, the increase of plant transpiration and soil evaporation might further aggravate soil water loss and reduce water availability for plants, which would make A. georgei and L. potaninii more vulnerable to drought stress.

The impaired biosynthetic networks in defective tapetum lead to male sterility in watermelon.

Heterosis has been widely applied in watermelon breeding, because of the higher resistance and yield of hybrid. As the basis of heterosis utilization, genic male sterility (GMS) is an important tool for facilitating hybrid seed production, while the detailed mechanism in watermelon is still largely unknown. Here, we report a spontaneous mutant Se18 exhibited complete male sterility due to the uniquely multilayered tapetum and the un-meiotic pollen mother cells during pollen development. Using TMT based quantitative proteomic analyses, a total of 348 differentially abundant proteins (DAPs) were detected with the overwhelming majority down-regulated in mutant Se18. By analyzing the putative orthologs/homologs of Arabidopsis GMS related genes, the biosynthesis and transport of sporopollenin and tryphine precursors were predictably altered in mutant compared to its sibling wild type. Moreover, the general phenylpropanoid pathway as well as its related metabolisms was also expectably impaired in mutant, coincident with the pale yellow petals. Notably, some key transcriptional factors regulating tapetum development, together with their down-regulated targets, offered potentially valuable candidates regarding of male sterility. Collectively, the disrupted regulatory networks underlying male sterility of watermelon was proposed, which provide novel insights into genetic mechanism of male reproductive process and rich gene resources for future research. SIGNIFICANCE: Watermelon is an importantly economical cucurbit crop worldwide, with high nutritional value. Although several male sterile mutants have been identified in watermelon, the underlying molecular mechanism is poorly elucidated. Comparative cytological analysis revealed that the defective development of tapetum was responsible for male sterility in mutant Se18. Combined with the morphological comparison, male floral buds at 2.0-2.5 mm in diameter were confirmed with no obvious phenotypic differences but distinct cytological defects, which were in turn sampled for TMT based proteomic analyses. Referring to functionally characterized GMS related genes, the genetic pathway DYT1-TDF1-AMS-MS188-MS1 regulating tapetum development, together with some downstream targets, were considerably altered in mutant Se18. Moreover, enrichment analyses illustrated the general phenylpropanoid related metabolisms, as well as the biosynthesis and transport of sporopollenin and tryphine precursors, were significantly disrupted in defective anther development. Collectively, the proposed regulatory networks in watermelon not only contribute to a better understanding of molecular mechanisms underlying male sterility, but also provide valuable GMS related candidates for future researches.