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Background Cold stress adversely influences rapeseeds ( Brassica napus L.) growth and yield during winter and spring seasons. Hydrogen (H 2 ) is a potential gasotransmitter that is used to enhance tolerance against abiotic stress, including cold stress. However, convenience and stability are two crucial limiting factors upon the application of H 2 in field agriculture. To explore the application of H 2 in field, here we evaluated the role of ammonia borane (AB), a new candidate for a H 2 donor produced by industrial chemical production, in plant cold tolerance. Results The application with AB could obviously alleviate the inhibition of rapeseed seedling growth and reduce the oxidative damage caused by cold stress. The above physiological process was closely related to the increased antioxidant enzyme system and reestablished redox homeostasis. Importantly, cold stress-triggered endogenous H 2 S biosynthesis was further stimulated by AB addition. The removal or inhibition of H 2 S synthesis significantly abolished plant tolerance against cold stress elicited by AB. Further field experiments demonstrated that the phenotypic and physiological performances of rapeseed plants after challenged with cold stress in the winter and early spring seasons were significantly improved by administration with AB. Particularly, the most studied cold-stress response pathway, the ICE1-CBF-COR transcriptional cascade, was significantly up-regulated either. Conclusion Overall, this study clearly observed the evidence that AB-increased tolerance against cold stress could be suitable for using in field agriculture by stimulation of H 2 S signaling.

Sclerotinia stem rot caused by Sclerotinia sclerotiorum is a devastating disease for many important crops worldwide, including Brassica napus . Although numerous studies have been performed on the gene expression changes in B. napus and S. sclerotiorum , knowledge regarding the molecular mechanisms of B. napus – S. sclerotiorum interactions is limited. Here, we revealed the changes in the gene expression and related pathways in both B. napus and S. sclerotiorum during the sclerotinia stem rot (SSR) infection process using transcriptome analyses. In total, 1,986, 2,217, and 16,079 differentially expressed genes (DEGs) were identified in B. napus at 6, 24, and 48 h post-inoculation, respectively, whereas 1,511, 1,208, and 2,051 DEGs, respectively, were identified in S. sclerotiorum . The gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that most of the hormone-signaling pathways in B. napus were enriched, and thus, the hormone contents at four stages were measured. The DEGs and hormone contents revealed that salicylic acid was activated, while the jasmonic acid pathway was repressed at 24 h post-inoculation. Additionally, the expressional patterns of the cell wall-degrading enzyme-encoding genes in S. sclerotiorum and the hydrolytic enzymes in B. napus were consistent with the SSR infection process. The results contribute to a better understanding of the interactions between B. napus and S. sclerotiorum and the development of future preventive measures against SSR.

The load current of the new power system has significant characteristics on a wide dynamic range, which poses challenges to current sensing technologies. This paper proposes a magnetic-sensitive element based on NdFeB/Lead Zirconate Titanate (PZT) magnetoelectric composite materials, and further develops a magnetoelectric coupling current sensor. The sensor operates in torque mode, enabling the detection of both wide dynamic range alternating currents and weak alternating currents. Experimental studies show that the sensor achieved a power-frequency current detection sensitivity of 15.56 mV/A, a linear range of (0–120) A, and a detection limit of 153 μA. The results indicate that the sensor exhibits high sensitivity in alternating current (AC) current detection, and at power frequency, possesses both a wide dynamic range and the capability to detect weak currents. Therefore, it shows great application potential in scenarios such as wide dynamic range AC current measurement and weak current detection in power systems.

As an important physiological and reproductive organ, the silique is a determining factor of seed yield and a breeding target trait in rapeseed ( Brassica napus L.). Genetic studies of silique-related traits are helpful for rapeseed marker-assisted high-yield breeding. In this study, a recombinant inbred population containing 189 lines was used to perform a quantitative trait loci (QTLs) analysis for five silique-related traits in seven different environments. As a result, 120 consensus QTLs related to five silique-related traits were identified, including 23 for silique length, 25 for silique breadth, 29 for silique thickness, 22 for seed number per silique and 21 for silique volume, which covered all the chromosomes, except C5. Among them, 13 consensus QTLs, one, five, two, four and one for silique length, silique breadth, silique thickness, seed number per silique and silique volume, respectively, were repeatedly detected in multiple environments and explained 4.38–13.0% of the phenotypic variation. On the basis of the functional annotations of Arabidopsis homologous genes and previously reported silique-related genes, 12 potential candidate genes underlying these 13 QTLs were screened and found to be stable in multiple environments by analyzing the re-sequencing results of the two parental lines. These findings provide new insights into the gene networks affecting silique-related traits at the QTL level in rapeseed.

Background Brassica napus provides approximately 13–16% of global vegetable oil for human consumption and biodiesel production. Plant height (PH) is a key trait that affects plant architecture, seed yield and harvest index. However, the genetic mechanism of PH in B. napus is poorly understood. Results A dwarf mutant df59 was isolated from a large-scale screening of an ethyl methanesulphonate-mutagenized rapeseed variety Ningyou 18. A genetic analysis showed that the dwarfism phenotype was controlled by one semi-dominant gene, which was mapped on C9 chromosome by quantitative trait loci sequencing analysis and designated as BnaDwf.C9. To fine-map BnaDwf.C9, two F2 populations were constructed from crosses between conventional rapeseed cultivars (Zhongshuang 11 and Holly) and df59. BnaDwf.C9 was fine-mapped to the region between single-nucleotide polymorphism (SNP) markers M14 and M4, corresponding to a 120.87-kb interval of the B. napus ‘Darmor-bzh’ genome. Within this interval, seven, eight and nine annotated or predicted genes were identified in “Darmor-bzh”, “Ningyou 7” and “Zhongshuang 11” reference genomes, respectively. In addition, a comparative transcriptome analysis was performed using stem tips from Ningyou 18 and df59 at the stem elongation stage. In total, 3995 differentially expressed genes (DEGs) were identified. Among them, 118 DEGs were clustered in plant hormone-related signal transduction pathways, including 81 DEGs were enriched in auxin signal transduction. Combining the results of fine-mapping and transcriptome analyses, BnaC09g20450D was considered a candidate gene for BnaDwf.C9, which contains a SNP that co-segregated in 4746 individuals. Finally, a PCR-based marker was developed based on the SNP in BnaC09g20450D. Conclusions The combination of quantitative trait loci sequencing, fine-mapping and genome-wide transcriptomic analysis revealed one candidate gene located within the confidence interval of 120.87-kb region. This study provides a new genetic resource for semi-dwarf breeding and new insights into understanding the genetic architecture of PH in B. napus.

Increasing leaf chlorophyll content in crops through genetic improvement is a feasible way to increase crop yield. However, the genetic mechanism that regulates the chlorophyll content of rapeseed leaves is not clear, which is not conducive to improving it through genetic pathways. In this study, a population of 189 recombinant inbred lines of Brassica napus was used to identify quantitative trait loci (QTLs) that regulate leaf chlorophyll content. A total of 12 QTLs were identified, of which two QTLs, qCHC.A6-2 and qCHC.C5-1 , explained 10.19% and 13.70% of the phenotypic variations in chlorophyll content, respectively, and were considered to be major QTLs. Furthermore, five of the 12 QTLs were inherited from APL01, while seven were inherited from Holly. Comparative transcriptomic analysis revealed that the differential expression of genes associated with the response to light stimulation, chloroplast organization, and glutathione peroxidase activity is the molecular basis for the difference in leaf chlorophyll content between APL01 and Holly. Further combining the variation analysis of the genomic DNA sequence and the functional annotation of homologous genes, four promising candidate genes ( BnaA06g37690D , BnaA06g37710D , BnaC05g00280D, and BnaC05g00300D ) were obtained, all of which are potentially involved in the response to light stimulation and/or chloroplast organization. These results help to clarify the genetic mechanism of chlorophyll content in B. napus leaves.

The rapeseed branch angle is an important morphological trait because an adequate branch angle enables more efficient light capture under high planting densities. Here, we report that the average angle of the five top branches provides a reliable representation of the average angle of all branches. Statistical analyses revealed a significantly positive correlation between the branch angle and multiple plant-type and yield-related traits. The 60 K Brassica Infinium ® single nucleotide polymorphism (SNP) array was utilized to genotype an association panel with 520 diverse accessions. A genome-wide association study was performed to determine the genetic architecture of branch angle and 56 loci were identified as being significantly associated with the branch angle trait via three models, including a robust, novel, nonparametric Anderson-Darling (A-D) test. Moreover, these loci explained 51.1% of the phenotypic variation when a simple additive model was applied. Within the linkage disequilibrium (LD) decay ranges of 53 loci, we observed plausible candidates orthologous to documented Arabidopsis genes, such as LAZY1 , SGR2 , SGR4 , SGR8 , SGR9 , PIN3 , PIN7 , CRK5 , TIR1 and APD7 . These results provide insight into the genetic basis of the branch angle trait in rapeseed and might facilitate marker-based breeding for improvements in plant architecture.

Brassica napus is an important oil crop worldwide, and its shoots are rich in vitamin C, calcium, and selenium. Functional oilseed-vegetable-dual-purpose varieties can increase the subsidiary value of B. napus . Consumption of high-calcium B. napus shoots can effectively help provide essential elements to the human body. To investigate the genetic mechanisms underlying the calcium concentrations of B. napus shoots, quantitative trait loci (QTL) mapping, using a population of 189 recombinant inbred lines, and a genome-wide association study, using an association panel of 202 diverse accessions, were performed. A total of 12 QTLs controlling calcium content were identified using the recombinant inbred line population in five environments. Among them, qCaC.22GY-A05-1 was considered the major QTL, with a phenotypic variation of 10.10%. In addition, 228 single nucleotide polymorphisms significantly related to calcium content were identified using the genome-wide association study in six environments, and they were distributed on all of the chromosomes, except A10. Finally, 10 candidate genes involved in regulating calcium absorption and transport in B. napus shoots were identified. However, no overlapping intervals were found through a comprehensive analysis of the two datasets. These results provide valuable information for understanding the genetic control of calcium concentration in B. napus shoots.

Background The fatty acid composition of B. napus ’ seeds determines the oil’s nutritional and industrial values, and affects seed germination. Many studies have reported correlations among C16:0, C18:0, C18:1, C18:2 and C18:3 based on phenotypic data; however, the genetic basis of the fatty acid composition in B. napus is still not well understood. Results In this study, unconditional and conditional quantitative trail locus (QTL) mapping analyses were conducted using a recombinant inbred line in six environments. In total, 21 consensus QTLs each for C16:0, C18:0 and C18:2, 16 for C18:1 and 22 for C18:3 were detected by unconditional mapping. The QTLs with overlapping confidence intervals were integrated into 71 pleiotropically unique QTLs by meta-analysis. Two major QTLs, uuqA5–6 and uuqA5–7 , simultaneously affected the fatty acids, except C18:0, in most of environments, with the homologous genes fatty acid desaturase 2 ( FAD2 ) and glycerol-3-phosphate sn-2-acyltransferase 5 ( GPAT5 ) occurring in the confidence interval of uuqA5–6 , while phosphatidic acid phosphohydrolase 1 ( PAH1 ) was assigned to uuqA5–7 . Moreover, 49, 30, 48, 60 and 45 consensus QTLs were detected for C16:0, C18:0, C18:1, C18:2 and C18:3, respectively, by the conditional mapping analysis. In total, 128 unique QTLs were subsequently integrated from the 232 conditional consensus QTLs. A comparative analysis revealed that 63 unique QTLs could be identified by both mapping methodologies, and 65 additional unique QTLs were only identified in conditional mapping. Conclusions Thus, conditional QTL mapping for fatty acids may uncover numerous additional QTLs that were inhibited by the effects of other traits. These findings provide useful information for better understanding the genetic relationships among fatty acids at the QTL level.

Chloroplast development is crucial for photosynthesis and plant growth and many factors are involved in its regulation. The regulatory mechanism differs in different green tissues, and previous studies have focused on chloroplasts in leaves. In this study, a mutant with sepal-specific chlorophyll-deficiency was observed in Brassica napus and named as df74. Genetic analysis indicated that the phenotype was controlled by a single recessive nuclear gene. The gene was located on chromosome C08 by bulked-segregant analysis with whole-genome sequencing, which was designated as BnC08.cds . To fine-map the BnC08.cds , a F 2 population was created from the cross of df74 and Zhongshuang11 (ZS11). Finally, the BnC08.cds was fine-mapped in the region between the single-nucleotide polymorphism (SNP) markers M5 and M6, corresponding to a 228.72 kb interval of the B. napus “ZS11” genome. Eighteen genes were predicted in the target region, and it was speculated that BnaC08G0442100ZS was the most likely candidate gene based on the results of transcriptome analyses and sequence variation analyses. These results provide a foundation to explore the regulation of chloroplast development in sepals.