Asparagine endopeptidase deficiency mitigates radiation-induced brain injury by suppressing microglia-mediated neuronal senescence.

Mounting evidence supports the role of neuroinflammation in radiation-induced brain injury (RIBI), a chronic disease characterized by delayed and progressive neurological impairment. Asparagine endopeptidase (AEP), also known as legumain (LGMN), participates in multiple malignancies and neurodegenerative diseases and may potentially be involved in RIBI. Here, we found AEP expression was substantially elevated in the cortex and hippocampus of wild-type (Lgmn+/+) mice following whole-brain irradiation. Lgmn knockout (Lgmn-/-) alleviated neurological impairment caused by whole-brain irradiation by suppressing neuronal senescence. Bulk RNA and metabolomic sequencing revealed AEP's involvement in the antigen processing and presentation pathway and neuroinflammation. This was further confirmed by co-culturing Lgmn+/+ primary neurons with the conditioned media derived from irradiated Lgmn+/+ or Lgmn-/- primary microglia. Furthermore, esomeprazole inhibited the enzymatic activity of AEP and RIBI. These findings identified AEP as a critical factor of neuroinflammation in RIBI, highlighting the prospect of targeting AEP as a therapeutic approach.

Oncometabolite 2-hydroxyglutarate regulates anti-tumor immunity.

"Oncometabolite" 2-hydroxyglutarate (2-HG) is an aberrant metabolite found in tumor cells, exerting a pivotal influence on tumor progression. Recent studies have unveiled its impact on the proliferation, activation, and differentiation of anti-tumor T cells. Moreover, 2-HG regulates the function of innate immune components, including macrophages, dendritic cells, natural killer cells, and the complement system. Elevated levels of 2-HG hinder α-KG-dependent dioxygenases (α-KGDDs), contributing to tumorigenesis by disrupting epigenetic regulation, genome integrity, hypoxia-inducible factors (HIF) signaling, and cellular metabolism. The chiral molecular structure of 2-HG produces two enantiomers: D-2-HG and L-2-HG, each with distinct origins and biological functions. Efforts to inhibit D-2-HG and leverage the potential of L-2-HG have demonstrated efficacy in cancer immunotherapy. This review delves into the metabolism, biological functions, and impacts on the tumor immune microenvironment (TIME) of 2-HG, providing a comprehensive exploration of the intricate relationship between 2-HG and antitumor immunity. Additionally, we examine the potential clinical applications of targeted therapy for 2-HG, highlighting recent breakthroughs as well as the existing challenges.

Development and validation of functional kompetitive allele-specific PCR markers for herbicide resistance in Brassica napus.

Effective weed control in the field is essential for maintaining favorable growing conditions and rapeseed yields. Sulfonylurea herbicides are one kind of most widely used herbicides worldwide, which control weeds by inhibiting acetolactate synthase (ALS). Molecular markers have been designed from polymorphic sites within the sequences of ALS genes, aiding marker-assisted selection in breeding herbicide-resistant rapeseed cultivars. However, most of them are not breeder friendly and have relatively limited application due to higher costs and lower throughput in the breeding projects. The aims of this study were to develop high throughput kompetitive allele-specific PCR (KASP) assays for herbicide resistance. We first cloned and sequenced BnALS1 and BnALS3 genes from susceptible cultivars and resistant 5N (als1als1/als3als3 double mutant). Sequence alignments of BnALS1 and BnALS3 genes for cultivars and 5N showed single nucleotide polymorphisms (SNPs) at positions 1676 and 1667 respectively. These two SNPs for BnALS1 and BnALS3 resulted in amino acid substitutions and were used to develop a KASP assay. These functional markers were validated in three distinct BC1F2 populations. The KASP assay developed in this study will be valuable for the high-throughput selection of elite materials with high herbicide resistance in rapeseed breeding programs.

Integrated analysis of transcriptome and metabolome reveals insights for low-temperature germination in hybrid rapeseeds (Brassica napus L.).

Rapeseed (Brassica napus L.) is an important oil-producing crop in China. However, cold stress in winter can adversely affect rapeseed germination and subsequently result in poor seed yield at the mature stage. Studies of differences in the transcriptional and metabolic levels of rapeseed under cold stress can improve our understanding of low-temperature germination (LTG). The current study aimed to identify the cold stress-responsive genes, metabolites, and metabolic pathways based on a combined transcriptome and metabolome analysis to understand the difference of LTG and tolerance mechanisms in the cold-tolerant (Yueyou1301, YY1301) and cold-normal (Fengyou737, FY737) rapeseed varieties. Compared to FY737, YY1301 had a higher germination rate, indole acetic acid (IAA) and gibberellic acid (GA)/(abscisic acid) ABA levels at 7.5 °C. A total of 951 differentially expressed genes (DEGs) and 86 differentially accumulated metabolites (DAMs) were identified in two rapeseed varieties. Conjoint analysis revealed 12 DAMs and 5 DEGs that were strongly correlated in inducing rapeseed LTG, which were mainly related to carbohydrate and amino acid metabolism, specifically the pathway of glutathione metabolism and starch and sucrose metabolism. These results suggest that the DAMs and DEGs involved in crucial biological pathways may regulate the LTG of rapeseed. It increases the understanding of the molecular mechanisms underlying the adaptation of rapeseed to LTG.

AEP-cleaved DDX3X induces alternative RNA splicing events to mediate cancer cell adaptation in harsh microenvironments.

Oxygen and nutrient deprivation are common features of solid tumors. Although abnormal alternative splicing (AS) has been found to be an important driving force in tumor pathogenesis and progression, the regulatory mechanisms of AS that underly the adaptation of cancer cells to harsh microenvironments remain unclear. Here, we found that hypoxia- and nutrient deprivation-induced asparagine endopeptidase (AEP) specifically cleaved DDX3X in a HIF1A-dependent manner. This cleavage yields truncated carboxyl-terminal DDX3X (tDDX3X-C), which translocates and aggregates in the nucleus. Unlike intact DDX3X, nuclear tDDX3X-C complexes with an array of splicing factors and induces AS events of many pre-mRNAs; for example, enhanced exon skipping (ES) in exon 2 of the classic tumor suppressor PRDM2 leads to a frameshift mutation of PRDM2. Intriguingly, the isoform ARRB1-Δexon 13 binds to glycolytic enzymes and regulates glycolysis. By utilizing in vitro assays, glioblastoma organoids, and animal models, we revealed that AEP/tDDX3X-C promoted tumor malignancy via these isoforms. More importantly, high AEP/tDDX3X-C/ARRB1-Δexon 13 in cancerous tissues was tightly associated with poor patient prognosis. Overall, our discovery of the effect of AEP-cleaved DDX3X switching on alternative RNA splicing events identifies a mechanism in which cancer cells adapt to oxygen and nutrient shortages and provides potential diagnostic and/or therapeutic targets.

CHRM3 is a novel prognostic factor of poor prognosis and promotes glioblastoma progression via activation of oncogenic invasive growth factors.

Glioblastoma (GBM) is the most aggressive cancer of the brain and has a high mortality rate due to the lack of effective treatment strategy. Clarification of molecular mechanisms of GBM's characteristic invasive growth is urgently needed to improve the poor prognosis. Single-nuclear sequencing of primary and recurrent GBM samples revealed that levels of M3 muscarinic acetylcholine receptor (CHRM3) were significantly higher in the recurrent samples than in the primary samples. Moreover, immunohistochemical staining of an array of GBM samples showed that high levels of CHRM3 correlated with poor prognosis, consistent with The Cancer Genome Atlas database. Knockdown of CHRM3 inhibited GBM cell growth and invasion. An assay of orthotopic GBM animal model in vivo indicated that inhibition of CHRM3 significantly suppressed GBM progression with prolonged survival time. Transcriptome analysis revealed that CHRM3 knockdown significantly reduced an array of classic factors involved in cancer invasive growth, including MMP1/MMP3/MMP10/MMP12 and CXCL1/CXCL5/CXCL8. Taken together, CHRM3 is a novel and vital factor of GBM progression via regulation of multiple oncogenic genes and may serve as a new biomarker for prognosis and therapy of GBM patients.

Eukaryotic initiation factor 4 A-3 promotes glioblastoma growth and invasion through the Notch1-dependent pathway.

BACKGROUND: As an adult tumor with the most invasion and the highest mortality rate, the inherent heterogeneity of glioblastoma (GBM) is the main factor that causes treatment failure. Therefore, it is important to have a deeper understanding of the pathology of GBM. Some studies have shown that Eukaryotic Initiation Factor 4A-3 (EIF4A3) can promote the growth of many people's tumors, and the role of specific molecules in GBM remains unclear. METHODS: The correlation between the expression of EIF4A3 gene and its prognosis was studied in 94 GBM patients using survival analysis. Further in vitro and in vivo experiments, the effect of EIF4A3 on GBM cells proliferation, migration, and the mechanism of EIF4A3 on GBM was explored. In addition, combined with bioinformatics analysis, we further confirmed that EIF4A3 contributes to the progress of GBM. RESULTS: The expression of EIF4A3 was upregulated in GBM tissues, and high expression of EIF4A3 is associated with poor prognosis in GBM. In vitro, knockdown of EIF4A3 significantly reduced the proliferation, migration, and invasion abilities of GBM cells, whereas overexpression of EIF4A3 led to the opposite effect. The analysis of differentially expressed genes related to EIF4A3 indicates that it is involved in many cancer-related pathways, such as Notch and JAK-STAT3 signal pathway. In Besides, we demonstrated the interaction between EIF4A3 and Notch1 by RNA immunoprecipitation. Finally, the biological function of EIF4A3-promoted GBM was confirmed in living organisms. CONCLUSION: The results of this study suggest that EIF4A3 may be a potential prognostic factor, and Notch1 participates in the proliferation and metastasis of GBM cells mediated by EIF4A3.

An inflammatory-related genes signature based model for prognosis prediction in breast cancer.

Background: Breast cancer has become the most common malignant tumor in the world. It is vital to discover novel prognostic biomarkers despite the fact that the majority of breast cancer patients have a good prognosis because of the high heterogeneity of breast cancer, which causes the disparity in prognosis. Recently, inflammatory-related genes have been proven to play an important role in the development and progression of breast cancer, so we set out to investigate the predictive usefulness of inflammatory-related genes in breast malignancies. Methods: We assessed the connection between Inflammatory-Related Genes (IRGs) and breast cancer by studying the TCGA database. Following differential and univariate Cox regression analysis, prognosis-related differentially expressed inflammatory genes were estimated. The prognostic model was constructed through the Least Absolute Shrinkage and Selector Operation (LASSO) regression based on the IRGs. The accuracy of the prognostic model was then evaluated using the Kaplan-Meier and Receiver Operating Characteristic (ROC) curves. The nomogram model was established to predict the survival rate of breast cancer patients clinically. Based on the prognostic expression, we also looked at immune cell infiltration and the function of immune-related pathways. The CellMiner database was used to research drug sensitivity. Results: In this study, 7 IRGs were selected to construct a prognostic risk model. Further research revealed a negative relationship between the risk score and the prognosis of breast cancer patients. The ROC curve proved the accuracy of the prognostic model, and the nomogram accurately predicted survival rate. The scores of tumor-infiltrating immune cells and immune-related pathways were utilized to calculate the differences between the low- and high-risk groups, and then explored the relationship between drug susceptibility and the genes that were included in the model. Conclusion: These findings contributed to a better understanding of the function of inflammatory-related genes in breast cancer, and the prognostic risk model provides a potentially promising prognostic strategy for breast cancer.

A nomogram to predict survival probability of gastric cancer patients undergoing radical surgery and adjuvant chemotherapy.

Gastric cancer (GC) is the third-leading cause of cancer mortality worldwide. The aim of this study was to develop a nomogram that estimates 1-year, 3-year, and 5-year survival probability of GC patients after D2 gastrectomy combined with adjuvant chemotherapy. The results showed that median age is 58 (range: 18-85) years in the training cohort and 59 (range: 32-85) years in the validation cohort. On multivariate analysis, four factors were found to be significantly associated with worse overall survival (OS): late TNM stage, positive resection margin, preoperative carcinoembryonic antigen (CEA) level, and single chemotherapy regimens compared with multiple chemotherapy regimens. All of these findings were validated in the validation cohort. Furthermore, the four factors were included in the final nomogram for the prediction of 1-year, 3-year, and 5-year survival probability, with accurate calibration and reasonable discrimination (C-index = 0.676 for training cohort, and C-index = 0.664 for validation cohort). The AUC values analyzed by the ROC analysis demonstrated a good predictive accuracy of the nomogram for OS (1-year, 3-year, and 5-year OS were 94.43%, 77.42%, and 73.03% in the training cohort, respectively; 96.95%, 81.54%, and 73.41% in the validation cohort, respectively). In conclusion, the proposed nomogram may be used to objectively and accurately predict survival probability of GC patients in a multi-institutional clinical setting.

Case fatality rate of the adult in-patients with COVID-19 and digestive system tumors: A systematic review and meta-analysis.

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, endoscopic screening for gastrointestinal tumors was suspended or delayed in most countries. Thus, our study aimed to quantify the impact of COVID-19 on the clinical outcomes of patients with digestive system tumors through a systematic review and meta-analysis. METHODS: We systematically searched the PubMed, Web of Science, Cochrane Library, and Embase databases as of March 7, 2021 to identify the case fatality rate (CFR) of COVID-19 patients diagnosed with digestive system tumors. A random-effects model was used for meta-analysis, I2 was used to assess heterogeneity, and funnel plot was used to assess publication bias. RESULTS: A total of 13 studies were included, involving 2943 tumor patients with COVID-19, of which 871 were digestive system tumors, and the CFR was 24% (95% CI, 18%-30%; I2 = 55.7%). The mortality rate of colorectal cancer was 21% (95% CI, 14%-27%; I2 = 0.0%), gastric cancer was 25% (95% CI, 6%-45%; I2 = 0.0%), and hepatobiliary cancer was 29%. In general, there was no significant difference in the CFR of digestive system tumors. CONCLUSION: The combined CFR of digestive system tumors and COVID-19 patients was 24%, which is much higher than that of the general population. Under the premise of fully complying with the international guidelines to limit the spread of COVID-19, we call for the resumption of endoscopic screening programs and selective surgery as soon as possible. REGISTRATION INFORMATION: PROSPERO registration no. CRD42021248194.

Efficacy of Different Preemptive Analgesia on Postoperative Analgesia, Oxidative Stress, and Inflammatory Response after Gynecological Laparoscopic Surgery.

OBJECTIVE: To observe and compare the analgesic effects of oxycodone, pentazocine, and ketorolac tromethamine pre-emptive analgesia on gynecological laparoscopic patients after operation and the effects on oxidative stress and inflammatory reaction. METHODS: A total of 64 patients who underwent elective gynecological laparoscopic surgery in Yiwu Central Hospital from June 2019 to December 2020 were randomly divided into four groups (n = 16). Before anesthesia induction, oxycodone (group A), pentazocine (group B), ketorolac tromethamine (group C), and normal saline (group D) were, respectively, administered. Patients' mean arterial pressure (MAP) and heart rate (HR) changes, visual analogue scale (VAS), Bruggemann comfort scale (BCS), serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), blood glucose (CLU), serum cortisol level, postoperative adverse reactions, and additional analgesia were recorded at each time point. RESULTS: The MAP levels of T2 (immediate intubation), T3 (immediate catheter removal), and T4 (5 min after catheter removal) in the four groups were higher than those of T1 (quiescent state), and the HR levels T2, T3, and T4 were lower than those of T1 (P < 0.05). The MAP and HR levels of T2, T3, and T4 in patients of groups A, B, and C were lower than those of group D in the same period (P < 0.05). The VAS and BCS scores of groups A, B, and C at 1, 6, 12, and 24 h after operation were better than those of group D at the same time, and the scores of group A at 1 h and 6 h after operation were better than those of groups B and C at the same time (P < 0.05). The levels of serum TNF-α, IL-6, and CRP in the four groups of patients at 6, 12, and 24 h after operation were higher than those before operation, but those in groups A, B, and C were lower than those in group D, and those in group A were higher than those in groups B and C at 12 h and 24 h after operation (P < 0.05). The CLU and serum cortisol levels in the four groups were significantly higher at 6, 12, and 24 h after operation, but those in groups A, B, and C were lower than those in group D, and those in group A were lower than those in groups B and C at 6 and 12 h after operation (P < 0.05). There was no significant difference in the incidence of adverse reactions within 24 h between the four groups (P > 0.05). The incidence of additional analgesia in groups A, B, and C was lower than that in group D (P < 0.05). CONCLUSION: Oxycodone, pentazocine, and ketorolac tromethamine are effective and safe in inhibiting postoperative pain and the generation of inflammatory factors and relieving inflammatory state in gynecological laparoscopic pre-emptive analgesia. Oxycodone has better postoperative analgesic effect because it can effectively alleviate stress reaction.

Genomic alterations in biliary tract cancer predict prognosis and immunotherapy outcomes.

BACKGROUND: Recently, immunotherapy with immune checkpoint inhibitors (ICIs) has shown promising efficacy in biliary tract cancer (BTC), which includes gallbladder cancer (GBC) and cholangiocarcinoma (CHOL). Understanding the association between immunotherapy outcomes and the genomic profile of advanced BTC may further improve the clinical benefits from immunotherapy. METHODS: Genomic tumor DNA was isolated from 98 Chinese patients with advanced BTC and used for targeted next-generation sequencing of 416 cancer-related genes to identify the genomic alterations common to advanced BTC. Thirty-four patients had received ICI camrelizumab plus gemcitabine and oxaliplatin (from the NCT03486678 trial) as a first-line treatment. Tumor-infiltrating immune cells were evaluated using immunofluorescence staining. RESULTS: KRAS and TP53 mutations were much more frequent in the advanced-stage BTC cohort than in other cohorts with mostly early stage disease. Specifically, KRAS-TP53 co-mutations were favored in advanced CHOL, with a favorable response to immunotherapy, while single KRAS mutations predicted poor prognosis and immunotherapy outcomes for CHOL. Compared with GBC, CHOL had more mutations in genes involved in KRAS signaling; a high mutation load in these genes correlated with poor immunotherapy outcomes and may subsequently cause inferior immunotherapy outcomes for CHOL relative to GBC. Furthermore, a genomic signature including 11 genes was developed; their mutated subtype was associated with poor prognosis and immunotherapy outcomes in both CHOL and GBC. Transcriptome analyses suggested immune dysfunction in the signature mutated subtype, which was validated by tumor microenvironment (TME) evaluation based on detection of immune cell infiltration. Importantly, the signature wild-type subtype with favorable TME may be an advantageous population of immunotherapy. CONCLUSIONS: Genomic alterations in advanced BTC were associated with specific prognosis and immunotherapy outcomes. Combining genomic classification with TME evaluation further improved the stratification of immunotherapy outcomes.

Rim-differentiated Co-pillar[4+1]arenes.

A series of rim-differentiated Co-pillar[4+1]arenes featuring penta-substituted "upper" rims and mono-functionalisable "lower" rims was successfully synthesised and fully characterised. These novel pillar[5]arene-based scaffolds with clickable moieties and extra synthetic handles are versatile platforms for self-assembled molecular architectures and biological applications.

L1CAM overexpression promotes tumor progression through recruitment of regulatory T cells in esophageal carcinoma.

OBJECTIVE: L1 cell adhesion molecule (L1CAM) exhibits oncogenic activity in tumors. However, the link between L1CAM and the tumor microenvironment remains poorly understood in patients with esophageal squamous cell carcinoma (ESCC). In this study, we investigated how L1CAM expression in ESCC affects the oncogenic characteristics of tumor cells and the tumor microenvironment. METHODS: Human ESCC samples were collected, and the mRNA and protein levels of L1CAM were examined by real-time PCR and immunohistochemistry. Overexpression and knockdown gene expression assays were used for mechanistic studies. The cell proliferation and cell cycle were measured with CCK-8 assays and flow cytometry. Cell migration and invasion ability were measured with Transwell assays. Multiplex bead-based assays were performed to identity the factors downstream of L1CAM. Xenograft studies were performed in nude mice to evaluate the effects of L1CAM on tumor growth and regulatory T cell (Treg) recruitment. RESULTS: L1CAM expression was significantly elevated in ESCC tissues (P < 0.001) and correlated with poorer prognosis (P < 0.05). Ablation of L1CAM in ESCC cells inhibited tumor growth and migration, and increased tumor cell apoptosis (P < 0.05). In the tumor microenvironment, L1CAM expression correlated with Treg infiltration in ESCC by affecting CCL22 secretion. Mechanistically, L1CAM facilitated CCL22 expression by activating the PI3K/Akt/NF-κB signaling pathway. Furthermore, CCL22 promoted Treg recruitment to the tumor site; the Tregs then secreted TGF-ß, which in turn promoted L1CAM expression via Smad2/3 in a positive feedback loop. CONCLUSIONS: Our findings provide new insight into the mechanism of immune evasion mediated by L1CAM, suggesting that targeting L1CAM-CCL22-TGF-ß crosstalk between tumor cells and Tregs may offer a unique means to improve treatment of patients with ESCC.

LMI1-like genes involved in leaf margin development of Brassica napus.

In rapeseed (Brassica napus L.), leaf margins are variable and can be entire, serrate, or lobed. In our previous study, the lobed-leaf gene (LOBED-LEAF 1, BnLL1) was mapped to a 32.1 kb section of B. napus A10. Two LMI1-like genes, BnaA10g26320D and BnaA10g26330D, were considered the potential genes that controlled the lobed-leaf trait in rapeseed. In the present study, these two genes and another homologous gene (BnaC04g00850D) were transformed into Arabidopsis thaliana (L.) Heynh. plants to identify their functions. All three LMI1-like genes of B. napus produced serrate leaf margins. The expression analysis indicated that the expression level of BnaA10g26320D determined the difference between lobed- and entire-leaved lines in rapeseed. Therefore, it is likely that BnaA10g26320D corresponds to BnLL1.

Silicon micro-ring tunable laser for coherent optical communication.

A compact external cavity tunable laser based on a silicon hybrid micro-ring resonator is demonstrated. A theoretical model is also employed for design and analysis of the wavelength tuning performance of the device. In this model, the gain section of the device is simulated by a conventional multimode rate equation model, whereas all rest passive sections are modeled by the frequency domain method. Experimental results have shown that the output power of this device can reach 29 mW, with a linewidth less than 150 kHz. The tuning range is more than 17 nm in C-band with 60 dB side-mode-suppression-ratio (SMSR). This device shows a comparable performance with the commercial narrow linewidth laser as the source in coherent transmission systems.

Transcriptome analysis of Brassica napus pod using RNA-Seq and identification of lipid-related candidate genes.

BACKGROUND: Brassica napus is an important oilseed crop. Dissection of the genetic architecture underlying oil-related biological processes will greatly facilitates the genetic improvement of rapeseed. The differential gene expression during pod development offers a snapshot on the genes responsible for oil accumulation in. To identify candidate genes in the linkage peaks reported previously, we used RNA sequencing (RNA-Seq) technology to analyze the pod transcriptomes of German cultivar Sollux and Chinese inbred line Gaoyou. METHODS: The RNA samples were collected for RNA-Seq at 5-7, 15-17 and 25-27 days after flowering (DAF). Bioinformatics analysis was performed to investigate differentially expressed genes (DEGs). Gene annotation analysis was integrated with QTL mapping and Brassica napus pod transcriptome profiling to detect potential candidate genes in oilseed. RESULTS: Four hundred sixty five and two thousand, one hundred fourteen candidate DEGs were identified, respectively, between two varieties at the same stages and across different periods of each variety. Then, 33 DEGs between Sollux and Gaoyou were identified as the candidate genes affecting seed oil content by combining those DEGs with the quantitative trait locus (QTL) mapping results, of which, one was found to be homologous to Arabidopsis thaliana lipid-related genes. DISCUSSION: Intervarietal DEGs of lipid pathways in QTL regions represent important candidate genes for oil-related traits. Integrated analysis of transcriptome profiling, QTL mapping and comparative genomics with other relative species leads to efficient identification of most plausible functional genes underlying oil-content related characters, offering valuable resources for bettering breeding program of Brassica napus. CONCLUSIONS: This study provided a comprehensive overview on the pod transcriptomes of two varieties with different oil-contents at the three developmental stages.

Quantitative trait loci that control the oil content variation of rapeseed (Brassica napus L.).

KEY MESSAGE: This report describes an integrative analysis of seed-oil-content quantitative trait loci (QTL) in Brassica napus , using a high-density genetic map to align QTL among different populations. Rapeseed (Brassica napus) is an important source of edible oil and sustainable energy. Given the challenge involved in using only a few genes to substantially increase the oil content of rapeseed without affecting the fatty acid composition, exploitation of a greater number of genetic loci that regulate the oil content variation among rapeseed germplasm is of fundamental importance. In this study, we investigated variation in the seed-oil content among two related genetic populations of Brassica napus, the TN double-haploid population and its derivative reconstructed-F2 population. Each population was grown in multiple experiments under different environmental conditions. Mapping of quantitative trait loci (QTL) identified 41 QTL in the TN populations. Furthermore, of the 20 pairs of epistatic interaction loci detected, approximately one-third were located within the QTL intervals. The use of common markers on different genetic maps and the TN genetic map as a reference enabled us to project QTL from an additional three genetic populations onto the TN genetic map. In summary, we used the TN genetic map of the B. napus genome to identify 46 distinct QTL regions that control seed-oil content on 16 of the 19 linkage groups of B. napus. Of these, 18 were each detected in multiple populations. The present results are of value for ongoing efforts to breed rapeseed with high oil content, and alignment of the QTL makes an important contribution to the development of an integrative system for genetic studies of rapeseed.

Characterization of the quantitative trait locus OilA1 for oil content in Brassica napus.

Increasing seed oil content has become one of the most important breeding criteria in rapeseed (Brassica napus). However, oil content is a complex quantitative trait. QTL mapping in a double haploid population (SG population) emerging from a cross between a German (Sollux) and Chinese (Gaoyou) cultivars revealed one QTL for oil content on linkage group A1 (OilA1), which was mapped to a 17 cM genetic interval. To further validate and characterize the OilA1, we constructed a high-resolution map using B. rapa sequence resources and developed a set of near-isogenic lines (NILs) by employing a DH line SG-DH267 as donor and Chinese parent Gaoyou as recurrent background. The results showed highly conserved synteny order between B. rapa and B. napus within the linkage group A1 and revealed a possible centromere region between two markers ZAASA1-38 and NTP3 (2.5 cM). OilA1 was firstly validated by 250 BC5F2 plants and was confirmed in a 10.6 cM interval between the markers ZAASA1-47 and ZAASA1-77. Further substitution mapping was conducted by using two generations of QTL-NILs, 283 lines from eight BC5F3:4 families and 428 plants from six BC5F4 sub-NILs and thus narrowed the OilA1 interval to 6.9 cM and 4.3 cM (1.4 Mb), respectively. Field investigations with two replications using homozygous BC5F3:4 sister sub-NILs indicated that NILs, which carry a Sollux chromosome segment across the target region showed significant higher oil content (1.26 %, p < 0.001) than their sister NILs containing Gaoyou chromosome. The OilA1 locus is of particular interest for breeding purpose in China because 80 % of Chinese cultivars do not carry this desirable allele.