The genome-wide long hairpin RNA interference (lhRNAi) library is an important resource for plant gene function research. Molecularly characterizing lhRNAi mutant lines is crucial for identifying candidate genes associated with corresponding phenotypes. In this study, a dwarf and sterile line named P198 was screened from the Brassica napus (B. napus) RNAi library. Three different methods confirmed that eight copies of T-DNA are present in the P198 genome. However, only four insertion positions were identified in three chromosomes using fusion primer and nested integrated polymerase chain reaction. Therefore, the T-DNA insertion sites and copy number were further investigated using Oxford Nanopore Technologies (ONT) sequencing, and it was found that at least seven copies of T-DNA were inserted into three insertion sites. Based on the obtained T-DNA insertion sites and hairpin RNA (hpRNA) cassette sequences, three candidate genes related to the P198 phenotype were identified. Furthermore, the potential differentially expressed genes and pathways involved in the dwarfism and sterility phenotype of P198 were investigated by RNA-seq. These results demonstrate the advantage of applying ONT sequencing to investigate the molecular characteristics of transgenic lines and expand our understanding of the complex molecular mechanism of dwarfism and male sterility in B. napus.

BnSIP1-1 is the first identified SIP1 (6b Interacting Protein1) subfamily gene of the trihelix transcription factor family from Brassica napus (B. napus). We previously used a reverse genetic method to reveal its abiotic stress response function in endowing plants resistance to drought and salinity, as well as ABA (Abscisic acid). However, the molecular mechanisms of BnSIP1-1 are unclear. In this study, the global transcriptome files of BnSIP1-1-overexpressing transgenic and wildtype B. napus seedlings under ABA treatment were constructed using RNA-seq. A total of 1823 and 5512 DEGs (Differentially Expressed Genes) were identified in OE vs. WT and OE_ABA vs. WT_ABA comparison groups, which included 751 and 2567 up-regulated DEGs, and 1072 and 2945 down-regulated DEGs, separately. The impact of overexpressed BnSIP1-1 on plants was amplified by ABA, indicating BnSIP1-1 was an ABA-conditioned responsive gene. More interestingly, we found the reasons for BnSIP1-1 increasing plants' insensitivity to ABA were not by regulating ABA synthesis and catabolism, but by manipulating ABA transportation, ABA signal perception and transduction, inositol phosphate metabolism, as well as endomembrane trafficking, indirectly suggesting this gene may play roles upstream of the core ABA response pathway. Our results provided new insights into improving the knowledge about the function of BnSIP1-1 and the ABA signaling mechanism in B. napus.

为了对基因组编辑产品进行精准定性和定量检测,以水稻SP1基因的编辑植株为材料,在编辑位点上下游设计通用引物,在编辑位点处设计基因编辑位点特异性TaqMan探针,建立了编辑位点特异性PCR方法.利用该方法可准确鉴定特异基因组编辑产品,检测灵敏度达到5～10拷贝,可在实时荧光PCR(qPCR)和微滴数字PCR(ddPCR)平台上对基因组编辑产品进行定量检测.由于数字PCR的微反应单元可消除野生型DNA对通用引物的竞争性消耗,与qPCR的定量结果相比,ddPCR定量结果具有更高的定量准确性.

New genes (or lineage-specific genes) can facilitate functional innovations. MALE STERILITY 5 (MS5) in Brassica napus is a fertility-related new gene, which has two wild-type alleles (BnMS5(a) and BnMS5(C)) and two mutant alleles (BnMS5(b) and BnMS5(d)) that could induce male sterility. Here, we studied the history and functional evolution of MS5 homologs in plants by phylogenetic analysis and molecular genetic experiments. We identified 727 MS5 homologs and found that they define a Brassicaceae-specific gene family that has expanded partly via multiple tandem gene duplications and also probably transpositions. The MS5 in B. napus is inherited from a basic diploid ancestor of B. rapa. Molecular genetic experiments indicate that BnMS5(a) and BnMS5(C) are functionally distinct in B. napus and that BnMS5(d) can inhibit BnMS5(a) in B. napus in a dosage-dependent manner. The BnMS5(a) protein can move in coordination with meiotic telomeres and interact with the nuclear envelope protein SUN1, with a possible crucial role in meiotic chromosome behavior. In summary, BnMS5 belongs to a Brassicaceae-specific new gene family, and has gained a novel function that is essential for male fertility in B. napus through neofunctionalization that has likely occurred since the origin of B. rapa.

Genome-edited plants created by genome editing technology have been approved for commercialization. Due to molecular characteristics that differ from classic genetically modified organisms (GMOs), establishing regulation-compliant analytical methods for identification and quantification of genome-edited plants has always been regarded as a challenging task. An editing-site-specific PCR method was developed based on the unique edited sequence in CAO1-edited rice plants. Test results of seven primer/probe sets indicated that this method can identify specific CAO1-edited rice from other CAO1-edited rice and wild types of rice with high specificity and sensitivity. The use of LNA (locked nucleic acid) in a probe can efficiently increase the specificity of the editing-site-specific PCR method at increased annealing temperature which can eliminate non-specific amplification of the non-target. The genome-edited ingredient content in blinded samples at the level of 0.1% to 5.0% was accurately quantified by this method on the ddPCR platform with RSD of <15% and bias in the range of ±17%, meeting the performance requirements for GMO detection method. The developed editing-site-specific PCR method presents a promising detection and quantification technique for genome-edited plants with known edited sequence.

转基因作物的分子特征为转基因的安全性评估和后续监测奠定了基础.由于靶点的特异性,以聚合酶链反应(PCR)为基础的传统分子特征鉴定方法不能全面检测外来基因的非预期插入、载体骨架残留及未知的转基因事件.更多新的育种技术产生的基因修饰作物也对传统分子特征鉴定方法提出了挑战.下一代测序技术,可以克服基于PCR的方法的某些局限性,提供快速、全面分子特征数据.本文综述了T-DNA整合的复杂机制,传统分子特征鉴定方法的局限性,高通量测序方法在转基因分子特征安全评价中的应用、遇到的挑战及应用策略,为转基因的安全评价工作提供借鉴.

With the successful completion of genomic sequencing for Brassica napus, identification of novel genes, determination of functions performed by genes, and exploring the molecular mechanisms underlying important agronomic traits were challenged. Mutagenesis-based functional genomics techniques including chemical, physical, and insertional mutagenesis have been used successfully in the functional characterization of genes. However, these techniques had their disadvantages and inherent limitations for allopolyploid Brassica napus, which contained a large number of homologous and redundant genes. Long intron-spliced hairpin RNA (ihpRNA) constructs which contained inverted repeats of the target gene separated by an intron, had been shown to be very effective in triggering RNAi in plants. In the present study, the genome-wide long ihpRNA library of B. napus was constructed with the rolling circle amplification (RCA)-mediated technology. Using the phytoene desaturase (PDS) gene as a target control, it was shown that the RCA-mediated long ihpRNA construct was significantly effective in triggering gene silence in B. napus. Subsequently, the resultant long ihpRNA library was transformed into B. napus to produce corresponding RNAi mutants. Among the obtained transgenic ihpRNA population of B. napus, five ihpRNA lines with observable mutant phenotypes were acquired including alterations in the floral model and the stamen development. The target genes could be quickly identified using specific primers. These results showed that the RCA-mediated ihpRNA construction method was effective for the genome-wide long ihpRNA library of B. napus, therefore providing a platform for study of functional genomics in allopolyploid B. napus.

异源四倍体油菜含有大量多拷贝基因及冗余基因,难以通过T-DNA插入、物理及化学诱变等常规突变体库创制方法发掘功能基因.为开发适应于油菜简单高效的突变体库创制方法,本研究通过滚环复制方法构建了甘蓝型油菜的花序lhRNAi文库,并对这种新型的干扰文库进行质量评估;然后将该花序lhRNAi文库对甘蓝型油菜进行遗传转化,获得763株T 0植株,从中鉴定分离出74株具有可见表型变异的花发育相关突变体,包括花瓣减少、形状异常,柱头卷曲,雄蕊退化萎缩,雄性不育、死蕾或花蕾闭合等.说明通过滚环复制介导的lhRNAi文库的构建方法可以成功应用到油菜中,这将为油菜花序发育相关基因的功能研究提供重要的研究平台.

Plant stems are involved in supporting the entire plant body, thus having an important effect on the yield of oilseed rape. The current understanding of the mechanism of stem development in oilseed rape is limited. In this study, a detailed comparative analysis of mRNA expression levels in Brassica napus between strong- (sample numbers 7110, 7031, 7029, 7095, and 7109) and weak-stemmed (sample numbers 7003, 7088, and 7123) was performed using RNA sequencing. A total of 1531 significantly differentially expressed genes were identified, including genes involved in cellulose and lignin biosynthesis, cell wall-binding proteins, and hormone biosynthesis and response genes. These results provide valuable insights into the molecular basis of stem development at the transcriptional level and will be helpful for revealing the regulatory mechanisms of stem growth in B. napus.