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SUMMARY: The successful interaction between pollen and stigma is a critical process for plant sexual reproduction, involving a series of intricate molecular and physiological events. After self‐compatible pollination, a significant reduction in reactive oxygen species (ROS) production has been observed in stigmas, which is essential for pollen grain rehydration and subsequent pollen tube growth. Several scavenging enzymes tightly regulate ROS homeostasis. However, the potential role of these ROS‐scavenging enzymes in the pollen‐stigma interaction in Brassica napus remains unclear. Here, we showed that the activity of ascorbate peroxidase (APX), an enzyme that plays a crucial role in the detoxification of hydrogen peroxide (H2O2), was modulated depending on the compatibility of pollination in B. napus. We then identified stigma‐expressed APX1s and generated pentuple mutants of APX1s using CRISPR/Cas9 technology. After compatible pollination, the BnaAPX1 pentuple mutants accumulated higher levels of H2O2 in the stigma, while the overexpression of BnaA09.APX1 resulted in lower levels of H2O2. Furthermore, the knockout of BnaAPX1 delayed the compatible response‐mediated pollen rehydration and germination, which was consistent with the effects of a specific APX inhibitor, ρ‐Aminophenol, on compatible pollination. In contrast, the overexpression of BnaA09.APX1 accelerated pollen rehydration and germination after both compatible and incompatible pollinations. However, delaying and promoting pollen rehydration and germination did not affect the seed set after compatible and incompatible pollination in APX1 pentuple mutants and overexpression lines, respectively. Our results demonstrate the fundamental role of BnaAPX1 in pollen rehydration and germination by regulating ROS homeostasis during the pollen‐stigma interaction in B. napus. Significance Statement: Our research found that self‐incompatibility in Brassica napus requires the accumulation of reactive oxygen species (ROS) levels in the stigma. We identified the importance of BnaAPX1 in regulating ROS homeostasis, which is critical for pollen rehydration and germination in B. napus. [ABSTRACT FROM AUTHOR]

Brassica napus, commonly known as rapeseed or canola, is a major oil crop contributing over 13% to the stable supply of edible vegetable oil worldwide. Identification and understanding the gene functions in the B. napus genome is crucial for genomic breeding. A group of genes controlling agronomic traits have been successfully cloned through functional genomics studies in B. napus. In this review, we present an overview of the progress made in the functional genomics of B. napus, including the availability of germplasm resources, omics databases and cloned functional genes. Based on the current progress, we also highlight the main challenges and perspectives in this field. The advances in the functional genomics of B. napus contribute to a better understanding of the genetic basis underlying the complex agronomic traits in B. napus and will expedite the breeding of high quality, high resistance and high yield in B. napus varieties. [ABSTRACT FROM AUTHOR]

Summary: Self‐incompatibility plays a vital role in angiosperms, by preventing inbreeding depression and maintaining genetic diversity within populations. Following polyploidization, many angiosperm species transition from self‐incompatibility to self‐compatibility.Here, we investigated the S‐locus in Brassicaceae and identified distinct origins for the sRNA loci, SMI and SMI2 (SCR Methylation Inducer 1 and 2), within the S‐locus. The SMI loci were found to be widespread in Cruciferae, whereas the SMI2 loci were exclusive to Brassica species.Additionally, we discovered four major S‐haplotypes (BnS‐1, BnS‐6, BnS‐7, and BnS‐1300) in rapeseed. Overexpression of BnSMI‐1 in self‐incompatible Brassica napus ('S‐70S1300S6') resulted in a significant increase in DNA methylation in the promoter regions of BnSCR‐6 and BnSCR‐1300, leading to self‐compatibility. Conversely, by overexpressing a point mutation of BnSmi‐1 in the 'S‐70S1300S6' line, we observed lower levels of DNA methylation in BnSCR‐6 and BnSCR‐1300 promoters. Furthermore, the overexpression of BnSMI2‐1300 in the 'SI‐326S7S6' line inhibited the expression of BnSCR‐7 through transcriptional repression of the Smi2 sRNA from the BnS‐1300 haplotype.Our study demonstrates that the self‐compatibility of rapeseed is determined by S‐locus sRNA‐mediated silencing of SCR after polyploidization, which helps to further breed self‐incompatible or self‐compatible rapeseed lines, thereby facilitating the utilization of heterosis. [ABSTRACT FROM AUTHOR]

Background: Brassica napus is an important oilseed crop providing high-quality vegetable oils for human consumption and non-food applications. However, the regulation between embryo and seed coat for the synthesis of oil and phenylpropanoid compounds remains largely unclear. Results: Here, we analyzed the transcriptomes in developing seeds at 2-day intervals from 14 days after flowering (DAF) to 64 DAF. The 26 high-resolution time-course transcriptomes are clearly clustered into five distinct groups from stage I to stage V. A total of 2217 genes including 136 transcription factors, are specifically expressed in the seed and show high temporal specificity by being expressed only at certain stages of seed development. Furthermore, we analyzed the co-expression networks during seed development, which mainly included master regulatory transcription factors, lipid, and phenylpropane metabolism genes. The results show that the phenylpropane pathway is prominent during seed development, and the key enzymes in the phenylpropane metabolic pathway, including TT5, BAN, and the transporter TT19, were directly or indirectly related to many key enzymes and transcription factors involved in oil accumulation. We identified candidate genes that may regulate seed oil content based on the co-expression network analysis combined with correlation analysis of the gene expression with seed oil content and seed coat content. Conclusions: Overall, these results reveal the transcriptional regulation between lipid and phenylpropane accumulation during B. napus seed development. The established co-expression networks and predicted key factors provide important resources for future studies to reveal the genetic control of oil accumulation in B. napus seeds. [ABSTRACT FROM AUTHOR]

Cytokinins (CKs) are phytohormones that promote cell division and differentiation. However, the regulation of CK distribution and homeostasis in Brassica napus is poorly understood. Here, the endogenous CKs were first quantified by LC-ESI-MS/MS in rapeseed tissues and visualized by TCSn::GUS reporter lines. Interestingly, the cytokinin oxidase/dehydrogenase BnaCKX2 homologs were mainly expressed in reproductive organs. Subsequently, the quadruple mutants of the four BnaCKX2 homologs were generated. Endogenous CKs were increased in the seeds of the BnaCKX2 quadruple mutants, resulting in a significantly reduced seed size. In contrast, overexpression of BnaA9.CKX2 resulted in larger seeds, probably by delaying endosperm cellularization. Furthermore, the transcription factor BnaC6.WRKY10b, but not BnaC6.WRKY10a, positively regulated BnaA9.CKX2 expression by binding directly to its promoter region. Overexpression of BnaC6.WRKY10b rather than BnaC6.WRKY10a resulted in lower concentration of CKs and larger seeds by activating BnaA9.CKX2 expression, indicating that the functional differentiation of BnaWRKY10 homologs might have occurred during B. napus evolution or domestication. Notably, the haploid types of BnaA9.CKX2 were associated with 1000-seed weight in the natural B. napus population. Overall, the study reveals the distribution of CKs in B. napus tissues, and shows that BnaWRKY10-mediated BnaCKX2 expression is essential for seed size regulation, providing promising targets for oil crop improvement. [ABSTRACT FROM AUTHOR]

Summary: Plant hormones are the intrinsic factors that control plant development. The integration of different phytohormone pathways in a complex network of synergistic, antagonistic and additive interactions has been elucidated in model plants. However, the systemic level of transcriptional responses to hormone crosstalk in Brassica napus is largely unknown. Here, we present an in‐depth temporal‐resolution study of the transcriptomes of the seven hormones in B. napus seedlings. Differentially expressed gene analysis revealed few common target genes that co‐regulated (up‐ and down‐regulated) by seven hormones; instead, different hormones appear to regulate distinct members of protein families. We then constructed the regulatory networks between the seven hormones side by side, which allowed us to identify key genes and transcription factors that regulate the hormone crosstalk in B. napus. Using this dataset, we uncovered a novel crosstalk between gibberellin and cytokinin in which cytokinin homeostasis was mediated by RGA‐related CKXs expression. Moreover, the modulation of gibberellin metabolism by the identified key transcription factors was confirmed in B. napus. Furthermore, all data were available online from http://yanglab.hzau.edu.cn/BnTIR/hormone. Our study reveals an integrated hormone crosstalk network in Brassica napus, which also provides a versatile resource for future hormone studies in plant species. [ABSTRACT FROM AUTHOR]

Summary: Pollen tube (PT) growth towards the micropyle is critical for successful double fertilization. However, the mechanism of micropyle-directed PT growth is still unclear in Brassica napus. In this study, two aspartate proteases, BnaAP36s and BnaAP39s, were identified in B. napus. BnaAP36s and BnaAP39s were localized to the plasma membrane. The homologues of BnaAP36 and BnaAP39 were highly expressed in flower organs, especially in the anther. Sextuple and double mutants of BnaAP36s and BnaAP39s were then generated using CRISPR/Cas9 technology. Compared to WT, the seed-set of cr-bnaap36 and cr-bnaap39 mutants was reduced by 50% and 60%, respectively. The reduction in seed-set was also found when cr-bnaap36 and cr-bnaap39 were used as the female parent in a reciprocal cross assay. Like WT, cr-bnaap36 and cr-bnaap39 pollen were able to germinate and the relative PTs were able to elongate in style. Approximately 36% and 33% of cr-bnaap36 and cr-bnaap39 PTs, respectively, failed to grow towards the micropyle, indicating that BnaAP36s and BnaAP39s are essential for micropyle-directed PT growth. Furthermore, Alexander's staining showed that 10% of cr-bnaap39 pollen grains were aborted, but not cr-bnaap36, suggesting that BnaAP39s may also affect microspore development. These results suggest that BnaAP36s and BnaAP39s play a critical role in the growth of micropyle-directed PTs in B. napus. [ABSTRACT FROM AUTHOR]

Brassica napus L. (canola, oil seed rape) is one of the world's most important oil seed crops. In the last four decades, the discovery of cytoplasmic male-sterility (CMS) systems and the restoration of fertility (Rf) genes in B. napus has improved the crop traits by heterosis. The homologs of Rf genes, known as the restoration of fertility-like (RFL) genes, have also gained importance because of their similarities with Rf genes. Such as a high non-synonymous/synonymous codon replacement ratio (dN/dS), autonomous gene duplications, and a possible engrossment in fertility restoration. B. napus contains 53 RFL genes on chromosomes A9 and C8. Our research aims to study the function of BnaRFL11 in fertility restoration using the CRISPR/Cas9 genome editing technique. A total of 88/108 (81.48%) T0 lines, and for T1, 110/145 (75%) lines carried T-DNA insertions. Stable mutations were detected in the T0 and T1 generations, with an average allelic mutation transmission rate of 81%. We used CRISPR-P software to detect off-target 50 plants sequenced from the T0 generation that showed no off-target mutation, signifying that if the designed sgRNA is specific for the target, the off-target effects are negligible. We also concluded that the mutagenic competence of the designed sgRNAs mediated by U6-26 and U6-29 ranged widely from 31% to 96%. The phenotypic analysis of bnarfl11 revealed defects in the floral structure, leaf size, branch number, and seed production. We discovered a significant difference between the sterile line and fertile line flower development after using a stereomicroscope and scanning electron microscope. The pollen visibility test showed that the pollen grain had utterly degenerated. The cytological observations of homozygous mutant plants showed an anther abortion stage similar to nap-CMS, with a Orf222, Orf139, Ap3, and nad5c gene upregulation. The bnarfl11 shows vegetative defects, including fewer branches and a reduced leaf size, suggesting that PPR-encoding genes are essential for the plants' vegetative and reproductive growth. Our results demonstrated that BnaRFL11 has a possible role in fertility restoration. The current study's findings suggest that CRISPR/Cas9 mutations may divulge the functions of genes in polyploid species and provide agronomically desirable traits through a targeted mutation. [ABSTRACT FROM AUTHOR]

SUMMARY: Canola (Brassica napus) is an important oil crop worldwide. The seed‐setting rate (SS) is a critical factor in determining its yield, and the development of pistils affects pollination and seed sets. However, research on seed‐setting defects has been limited owing to difficulties in the identification of phenotypes, mutations, and complex genetic mechanisms. In this study, we found a stigma defect (sd) mutant in B. napus, which had no nectary. The SS of sd mutants in the field was approximately 93.4% lower than that of the wild type. Scanning and transmission electron microscopy imaging of sd mutants showed a low density of stigma papillary cells and stigma papillary cell vacuoles that disappeared 16 h after flowering. Genetic analysis of segregated populations showed that two recessive nuclear genes are responsible for the mutant phenotype of sd. Based on re‐sequencing and map‐based cloning, we reduced the candidate sites on ChrA07 (BnaSSA07) and ChrC06 (BnaSSC06) to 30 and 67 kb, including six and eight predicted genes, respectively. Gene analyses showed that a pair of CRABS CLAW (CRC) homeologous genes at BnaSSA07 and BnaSSC06 were associated with the development of carpel and nectary. BnaSSA07.CRC and BnaSSC06.CRC candidate genes were found to be expressed in flower organs only, with significant differences in their expression in the pistils of the near‐isogenic lines. DNA sequencing showed transposon insertions in the upstream region and intron of the candidate gene BnaSSA07.crc. We also found that BnaSSC06.crc exists widely in the natural population and we give possible reasons for its widespread existence. Significance Statement: The BnaCRCs of domesticated preference are located at A07 and C06 within 30‐ and 67‐kb regions, respectively, as determined by re‐sequencing and map‐based cloning. They were positively correlated with the Brassica napus seed‐setting rate. [ABSTRACT FROM AUTHOR]

In this study, several lines of evidence showed that the BnaMPK3s-BnaARF2s module is critical for the regulation of organ size and yield in I B. napus i . Keywords: Brassica napus; BnaMPK3; BnaARF2; organ size EN Brassica napus BnaMPK3 BnaARF2 organ size 899 901 3 04/19/23 20230501 NES 230501 The larger organs have potential economic value in I Brassica napus i improvement and bioenergy production. Brassica napus, BnaMPK3, BnaARF2, organ size. [Extracted from the article]

Interspecific hybridization drives the evolution of angiosperms and can be used to introduce novel alleles for important traits or to activate heterosis in crop breeding. Hybridization brings together gene expression networks from two different species, potentially causing global alterations of gene expression in the F1 plants which is called 'transcriptome shock'. Here, we explored such a transcriptome shock in allotriploid Brassica hybrids. We generated interspecific F1 allotriploid hybrids between the allotetraploid species Brassica napus and three accessions of the diploid species Brassica rapa. RNA-seq of the F1 hybrids and the parental plants revealed that 26.34–30.89% of genes were differentially expressed between the parents. We also analyzed expression level dominance and homoeolog expression bias between the parents and the F1 hybrids. The expression-level dominance biases of the Ar, An, and Cn subgenomes was genotype and stage dependent, whereas significant homoeolog expression bias was observed among three subgenomes from different parents. Furthermore, more genes were involved in trans regulation than in cis regulation in allotriploid F1 hybrids. Our findings provide new insights into the transcriptomic responses of cross-species hybrids and hybrids showing heterosis, as well as a new method for promoting the breeding of desirable traits in polyploid Brassica species. [ABSTRACT FROM AUTHOR]

Brassica napus L. is a vital oil crop in China. As auxiliary tools for rapeseed breeding, transgenic technologies play a considerable role in heterosis, variety improvement, and pest resistance. Research on transgenic detection technologies is of great significance for the introduction, supervision, and development of transgenic rapeseed in China. However, the transgenic detection methods currently in use are complex and time-consuming, with low output. A single nucleotide polymorphism (SNP) chip can effectively overcome such limitations. In the present study, we collected 40 transgenic elements and designed 291 probes. The probe sequences were submitted to Illumina Company, and the Infinium chip technology was used to prepare SNP chips. In the present Brassica napus transgenic detection experiment, 84 high-quality probes of 17 transgenic elements were preliminarily screened, and genotyping effect was optimised for the probe signal value. Ultimately, a transgenic detection system for B. napus was developed. The developed system has the advantages of simple operation, minimal technical errors, and stable detection outcomes. A transgenic detection sensitivity test revealed that the probe designed could accurately detect 1% of transgenic samples and had high detection sensitivity. In addition, in repeatability tests, the CaMV35S promoter coefficient of variation was approximately 3.58%. Therefore, the SNP chip had suitable repeatability in transgene detection. The SNP chip developed could be used to construct transgenic detection systems for B. napus. [ABSTRACT FROM AUTHOR]

Summary: Seed oil content (SOC) and fatty acid (FA) composition determine the quality and economic value of rapeseed (Brassica napus). Little is known about the role of gibberellic acid (GA) in regulating FA biosynthesis in B. napus. Here, we discovered that four BnaRGAs (B. napus REPRESSOR OF GA), encoding negative regulators of GA signalling, were suppressed during seed development. Compared to the wild type, SOC was reduced in gain‐of‐function mutants bnaa6.rga‐D and ds‐3, which also showed reduced oleic acid and increased linoleic acid contents. By contrast, the loss‐of‐function quadruple mutant bnarga displayed higher SOC during early seed development than the wild type, with increased oleic acid and reduced linoleic acid contents. Notably, only BnaA6.RGA and BnaC7.RGA physically interacted with two BnaLEC1s, which function as essential transcription factors in FA biosynthesis. The FA composition did not significantly differ between bnarga bnalec1 sextuple mutants and bnalec1, suggesting that BnaLEC1s are epistatic to BnaRGAs in the regulation of FA composition. Furthermore, BnaLEC1‐induced activation of BnaABI3 expression was repressed by BnaA6.RGA, indicating that GA triggers the degradation of BnaRGAs to relieve their repression of BnaLEC1s, thus promoting the transcription of downstream genes to facilitate oil biosynthesis. Therefore, we uncovered a developmental stage‐specific role of GA in regulating oil biosynthesis via the GA‐BnaRGA‐BnaLEC1 signalling cascade, providing a novel mechanistic understanding of how phytohormones regulate FA biosynthesis in seeds. BnaRGAs represent promising targets for oil crop improvement. [ABSTRACT FROM AUTHOR]

Key message: The mutations BnA1.CER4 and BnC1.CER4 produce disordered wax crystals types and alter the composition of epidermal wax, causing increased cuticular permeability and sclerotium resistance. The aerial surfaces of land plants are coated with a cuticle, comprised of cutin and wax, which is a hydrophobic barrier for preventing uncontrolled water loss and environmental damage. However, the mechanisms by which cuticle components are formed are still unknown in Brassica napus L. and were therefore assessed here. BnA1.CER4 and BnC1.CER4, encoding fatty acyl-coenzyme A reductases localizing to the endoplasmic reticulum and highly expressed in leaves, were identified and functionally characterized. Expression of BnA1.CER4 and BnC1.CER4 cDNA in yeast (Saccharomyces cerevisiae) induced the accumulation of primary alcohols with chain lengths of 26 carbons. The mutant line Nilla glossy2 exhibited reduced wax crystal types, and wax composition analysis showed that the levels of branched primary alcohols were decreased, whereas those of the other branched components were increased. Further analysis showed that the mutant had reduced water retention but enhanced resistance to Sclerotinia sclerotiorum. Collectively, our study reports that BnA1.CER4 and BnC1.CER4 are fatty acyl-coenzyme A reductase genes in B. napus with a preference for branched substrates that participate in the biosynthesis of anteiso-primary alcohols. [ABSTRACT FROM AUTHOR]

Key message: A mitochondria-localized pentatricopeptide repeat protein was identified by positional cloning and transferred into the hau CMS line, where it successfully restored fertility Cytoplasmic male sterility (CMS) is a maternally inherited trait that can be controlled by restorer-of-fertility (Rf) genes present in the nucleus. The hau CMS was identified as a new form of CMS associated with the mitochondrial transcript orf288; however, a lack of a restorer gene has limited its utilization in Brassica crops. Here, the combination of Brassica 60 K array with bulk segregant analysis and map-based cloning was used to delimit the Rfh locus to an 82.2-kb region on chromosome A09. A candidate gene encoding a mitochondria-localized pentatricopeptide repeat (PPR) protein was identified and transferred into the hau CMS line, where it successfully restored the fertility of the hau CMS plants. Furthermore, the expression analysis showed that Rfh was highly expressed in the flower buds, and the sequence analysis results implied that functional divergence between RFH and rfh could be due to 59 amino acid residue differences in the deduced protein sequences. In addition, a co-separated molecular marker was developed based on the divergent sequences between the dominant and recessive alleles. These results will help enable the heterosis of Brassica crops in the future. [ABSTRACT FROM AUTHOR]

BnTIR: an online transcriptome platform for exploring RNA-seq libraries for oil crop Brassica napus Keywords: Brassica napus; transcriptome; Co-expression; database EN Brassica napus transcriptome Co-expression database 1895 1897 3 10/05/21 20211001 NES 211001 With the increasing availability of massive transcriptome data in plants, it is possible to construct a comprehensive database with multiple transcriptome data and online imputation tools. After entering the I Arabidopsis i gene ID, the phylogenetic tree and expression profile of I BAN i and their four I B. napus i homolog genes were generated in expression module, which were highly expressed at the beginning of the seed development and followed by decreasing expression (Figure 1l). [Extracted from the article]

Background: TERMINAL FLOWER 1 (TFL1) is a member of phosphatidylethanolamine-binding protein (PEBP) family, which plays an important role in the determination of floral meristem identity and regulates flowering time in higher plants. Results: Five BnaTFL1 gene copies were identified in the genome of Brassica napus. The phylogenetic analysis indicated that all five BnaTFL1 gene copies were clustered with their corresponding homologous copies in the ancestral species, B. rapa and B. oleracea. The expression of the BnaTFL1s were confined to flower buds, flowers, seeds, siliques and stem tissues and displayed distinct expression profiles. Knockout mutants of BnaC03.TFL1 generated by CRISPR/Cas9 exhibited early flowering phenotype, while the knockout mutants of the other gene copies had similar flowering time as the wild type. Furthermore, knock-out mutants of individual BnaTFL1 gene copy displayed altered plant architecture. The plant height, branch initiation height, branch number, silique number, number of seeds per silique and number of siliques on the main inflorescence were significantly reduced in the BnaTFL1 mutants. Conclusions: Our results indicated that BnaC03.TFL1 negatively regulates flowering time in B. napus. BnaC03.TFL1 together with the other BnaTFL1 paralogues are essential for controlling the plant architecture. [ABSTRACT FROM AUTHOR]

Drought is a major threat to plant growth and crop productivity. Reduced level of the gibberellin would result in increased drought tolerance, but the underlying mechanism is still unclear. In Brassica napus , there are four BnaRGA genes that code for DELLA proteins, negative regulators of GA signaling. Among them, expression of BnaA6.RGA was greatly induced by drought and abscisic acid (ABA). Previously, we created the gain-of-function mutant of BnaA6.RGA , bnaa6.rga-D , and the loss-of-function quadruple mutant, bnarga by CRISPR/Cas9, respectively. Here we show that bnaa6.rga-D displayed enhanced drought tolerance, and its stomatal closure was hypersensitive to ABA treatment. By contrast, bnarga displayed reduced drought tolerance and was less sensitive to ABA treatment, but there is no difference in drought tolerance between single BnaRGA mutant and WT, suggesting a functional redundancy between the BnaRGA genes in this process. Furthermore, we found that BnaRGAs were able to interact physically with BnaA10.ABF2, an essential transcription factor in ABA signaling. The BnaA10.ABF2-BnaA6.RGA protein complex greatly increased the expression level of the drought responsive gene BnaC9.RAB18. Taken together, this work highlighted the fundamental roles of DELLA proteins in drought tolerance in B. napus , and provide desirable germplasm for further breeding of drought tolerance in rapeseed. [ABSTRACT FROM AUTHOR]

Temperature-sensitive male sterility is a heritable agronomic trait affected by genotype-environment interactions. In rapeseed (Brassica napus), Polima (pol) temperature-sensitive cytoplasmic male sterility (TCMS) is commonly used for two-line breeding, as the fertility of pol TCMS lines can be partially restored at certain temperatures. However, little is known about the underlying molecular mechanism that controls fertility restoration. Therefore, we aimed to investigate the fertility conversion mechanism of the pol TCMS line at two different ambient temperatures (16 °C and 25 °C). Our results showed that the anthers developed and produced vigorous pollen at 16 °C but not at 25 °C. In addition, we identified a novel co-transcript of orf224-atp6 in the mitochondria that might lead to fertility conversion of the pol TCMS line. RNA-seq analysis showed that 1637 genes were significantly differentially expressed in the fertile flowers of 596-L when compared to the sterile flower of 1318 and 596-H. Detailed analysis revealed that differentially expressed genes were involved in temperature response, ROS accumulation, anther development, and mitochondrial function. Single-molecule long-read isoform sequencing combined with RNA sequencing revealed numerous genes produce alternative splicing transcripts at high temperatures. Here, we also found that alternative oxidase, type II NAD(P)H dehydrogenases, and transcription factor Hsfs might play a crucial role in male fertility under the low-temperature condition. RNA sequencing and bulked segregant analysis coupled with whole-genome sequencing identified the candidate genes involved in the post-transcriptional modification of orf224. Overall, our study described a putative mechanism of fertility restoration in a pol TCMS line controlled by ambient temperature that might help utilise TCMS in the two-line breeding of Brassica crops. [ABSTRACT FROM AUTHOR]

Self-incompatibility (SI) is a pollen-stigma recognition system controlled by a single and highly polymorphic genetic locus known as the S-locus. The S-locus exists in all Brassica napus (B. napus, AACC), but natural B. napus accessions are self-compatible. About 100 and 50 S haplotypes exist in Brassica rapa (AA) and Brassica oleracea (CC), respectively. However, S haplotypes have not been detected in B. napus populations. In this study, we detected the S haplotype distribution in B. napus and ascertained the function of a common S haplotype BnS-6 through genetic transformation. BnS-1/BnS-6 and BnS-7/BnS-6 were the main S haplotypes in 523 B. napus cultivars and inbred lines. The expression of SRK in different S haplotypes was normal (the expression of SCR in the A subgenome affected the SI phenotype) while the expression of BnSCR-6 in the C subgenome had no correlation with the SI phenotype in B. napus. The BnSCR-6 protein in BnSCR-6 overexpressed lines was functional, but the self-compatibility of overexpressed lines did not change. The low expression of BnSCR-6 could be a reason for the inactivation of BnS-6 in the SI response of B. napus. This study lays a foundation for research on the self-compatibility mechanism and the SI-related breeding in B. napus. [ABSTRACT FROM AUTHOR]

Self-incompatibility (SI) is an important genetic mechanism exploited by numerous angiosperm species to prevent inbreeding. This mechanism has been widely used in the breeding of SI trilinear hybrids of Brassica napus. The SI responses in these hybrids can be overcome by using a salt (NaCl) solution, which is used for seed propagation in SI lines. However, the mechanism underlying the NaCl-induced breakdown of the SI response in B. napus remains unclear. Here, we investigated the role of two key proteins, BnaPLDα1 and BnaMPK6, in the breakdown of SI induced by NaCl. Pollen grain germination and seed set were reduced in BnaPLDα1 triple mutants following incompatible pollination with NaCl treatment. Conversely, SI responses were partially abolished by overexpression of BnaC05.PLDα1 without salt treatment. Furthermore, we observed that phosphatidic acid (PA) produced by BnaPLDα1 bound to B. napus BnaMPK6. The suppression and enhancement of the NaCl-induced breakdown of the SI response in B. napus were observed in BnaMPK6 quadruple mutants and BnaA05.MPK6 overexpression lines, respectively. Moreover, salt-induced stigmatic reactive oxygen species (ROS) accumulation had a minimal effect on the NaCl-induced breakdown of the SI response. In conclusion, our results demonstrate the essential role of the BnaPLDα1-PA-BnaMPK6 pathway in overcoming the SI response to salt treatment in SI B. napus. Additionally, our study provides new insights into the relationship between SI signaling and salt stress response. A new molecular mechanism underlying the breakdown of the NaCl-induced self-incompatibility (SI) response in B. napus has been discovered. It involves the induction of BnaPLDα1 expression by NaCl, followed by the activation of BnaMPK6 through the production of phosphatidic acid (PA) by BnaPLDα1. Ultimately, this pathway leads to the breakdown of SI. The involvement of the BnaPLDα1-PA-BnaMPK6 pathway in overcoming the SI response following NaCl treatment provides new insights into the relationship between SI signalling and the response to salt stress. • BnaPLD1 positively regulates salt-breaking the SI response. • PA produced by BnaPLD1 bound to BnaMPK6, and BnaMPK6 positively regulates salt-breaking the SI response. • BnaPLDα1-PA-BnaMPK6 pathway is essential for salt-breaking the SI response in B.napus. [ABSTRACT FROM AUTHOR]

Interspecific hybridization is the intrinsic forces behind genome evolution. Long non-coding RNAs (lncRNAs) are important for plant biological processes regulation. However, it is unclear that these non-coding fractions are impacted by interspecific hybridization. Here we examined the profiles of lncRNAs by comparing them with coding genes in Brassica napus , three accessions of Brassica rapa , and their F 1 hybrids. 6206 high-confidential lncRNAs were identified in F 1 hybrids and their parentals, and the lncRNAs transcriptome in the F 1 hybrids was reprogrammed by the genome shock. Notably, genome-wide unbalanced of lncRNAs were observed between A n and A r subgenomes, ELD (Expression Level Dominance) was biased toward the A n -genome in F 1 hybrids, and ELD of non-conserved lncRNAs was more than conserved lncRNAs. Our findings demonstrate that the reprogramed lncRNAs acts as important role in enhancing plant plasticity, leading to the acquisition of desirable traits in polyploid Brassica species. • 6206 high-confidential lncRNAs were identified in Brassica napus , three accessions of the Brassica rapa , and their F1 hybrids at two development stages. • The expression of conserved lncRNAs (c-lncRNAs) was dosage dependent, and genome-wide unbalanced of lncRNAs were observed between An and Ar subgenomes. • 38 distinct modules were constructed by the co-expression network analysis of lncRNAs and different expressed genes. [ABSTRACT FROM AUTHOR]