2021年4月11日，中国农业科学院蔬菜花卉研究所甘蓝青花菜研究团队在期刊planta（2023 IF=4.3）上发表了题为Transcriptome and plant hormone analyses provide new insight into the molecular regulatory networks underlying hybrid lethality in cabbage (Brassica oleracea)的研究论文。论文的第一作者为肖志亮博士，通讯作者为庄木研究员和吕红豪研究员。

杂种致死（Hybrid lethality，HL）通过阻断种群间的基因交换，对种群的稳定起着至关重要的作用，但是其分子机制尚不清楚。作者通过对甘蓝杂种致死的表型、转录组和植物激素进行了分析。表型分析表明，杂种致死具有典型的细胞程序性死亡过程（Programmed cell death），一种基于时间分辨的RNA-seq（A time-resolved RNA-seq）鉴定到2724个差异表达基因（DEGs），功能注释表明杂种致死和防御反应密切相关。因此，作者在植物-病原菌互作途径和MAPK信号通路的基础上，构建了一个防御调控网络，其中包括与导致PCD的Ca2+和过氧化氢有关的DEGs。此外，还鉴定了和SA、JA等激素信号转导途径有关的重要DEGs，并且通过内源和外源施加SA、JA证实了这点。

Fig. 1 Phenotypes of the cabbage F1 hybrids and the 09–211 control. a The F1 hybrids was normal at two-leaf stage (HLN). b The F1 hybrids showed slight growth stunting at three-leaf stage (HLW1). c The F1 hybrids showed apparent growth stunting and slight yellowing (HLW2). d The F1 hybrids showed seriously growth arrest and apparent chlorosis (HLW3). e The leaves appeared completely chlorotic and the plants become wilt and dead (HLW4). f, g The parent line 09–211 grows normally with two to five leaves, respectively, corresponding to the five HL stages. Scale bars = 5 cm

Fig. 3 Analysis of DEGs in the four comparison groups. a Histogram showing the number of DEGs in the four comparison groups. b Venn diagram showing the mutual overlaps of DEGs in the four comparison groups. c Heat map showing a general overview of the expression patterns

Fig. 4 Functional annotation and classification and qRT-PCR verification of DEGs. a GO classifications. The GO terms are summarised on the basis of the three main categories (cellular components (CCs), molecular functions (MFs) and biological processes (BPs). The degree of significance of the enrichment of DEGs in a pathway is represented by −log10 (P value). b Top 20 pathways of KEGG functional enrichment among the DEGs. c qRT-PCR verification of the expression patterns of PR genes. The error bars represent the ± SE of three independent experiments (P ≤ 0.05)

Fig. 5 Association graph showing the relationships between three important pathways (‘plant–pathogen interaction’, ‘plant hormone signal transduction’, ‘MAPK signalling pathway-plant’) and the related core DEGs

Fig. 6 Possible functional defence network of cabbage hybrid lethality and a heat map of related DEGs. a Possible functional defence network of hybrid lethality. The upregulated DEGs in this category are red, the downregulated DEGs are green, and DEGs that are both, upregulated and downregulated, are orange. b H2O2 content.The error bars represent the ± SE of three independent experiments (P ≤ 0.05). c Heatmap of DEGs in the defence network

Fig. 7 Nine GO terms related to PCD and cell death and their expression patterns

Fig. 8 Plant hormone signal transduction pathway components and corresponding heat map expression profiles

Fig. 9 Fluctuations in endogenous SA and JA between the lethal individuals and normal individuals (control) from the F2 separated population and F1 hybrids in response to exogenous SA and JA treatment. a Endogenous SA content between the lethal individuals and normal individuals. b Endogenous JA content between the lethal individuals and normal individuals, the error bars represent the ± SE of three independent experiments (P ≤ 0.05). c F1 hybrids in response to exogenous SA and JA treatment. F1 hybrids treated with H2O exhibited initial hybrid lethal phenotyping (HLW1), F1 hybrids treated with SA grew normally, and F1 hybrids treated with JA exhibited moderate hybrid lethal phenotyping (HLW2). Scale bars = 5 cm

Fig. 10 Numbers and classification of differentially expressed TFs involved in hybrid lethality. Categories of transcription factors that constitute less than 1% of the total are not marked on the pie char