Li Shipeng, Zhang Jing, Chen Caiwu, Ali Ahmad, Wen Jing, Dai Cheng, Ma Chaozhi, Tu Jinxing, Shen Jinxiong, Fu Tingdong, Yi Bin
National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, National Engineering Research Center of Rapeseed, Huazhong Agricultural University, Wuhan, 430070, China.
BMC Plant Biol. 2024 Dec 19;24(1):1206. doi: 10.1186/s12870-024-05916-6.
Thermosensitive male sterility (TMS) is a heritable agronomic trait influenced by the interaction between genotype and environment. The anthers of plants are composed of various specialized cells, each of which plays different roles in plant reproduction. In rapeseed (Brassica napus L.), Polima (pol) temperature-sensitive cytoplasmic male sterility (TCMS) is widely used in two-line breeding because its fertility can be partially restored at certain temperatures. The pol-TCMS line exhibits abnormal anther development and pollen abortion at high (restrictive) temperatures (HT, 25 °C) compared to at low (permissive) temperatures (LT, 16 °C). However, the response of different anther cell types to HT and the dynamic regulation of genes under such conditions remain largely unknown.
We present the first single-cell transcriptomic atlas of Brassica napus early developing flower bud tissues in response to HT. We identified 8 cell types and 17 transcriptionally distinct cell clusters via known marker genes under LT and HT treatment conditions. Under HT conditions, changes in the gene expression patterns of different cell clusters were observed, with the number of down-regulated genes in various cell types exceeding that of up-regulated genes. Pseudotime trajectory analysis revealed that HT strongly affected the development of early stamen/anther tissue cells. In combination with the snRNA-seq, WGCNA, and bulk RNA-seq results, we found that many transcription factors play crucial roles in the response to HT, especially heat response family genes.
Our study revealed the transcriptional regulatory network of floral bud tissue in the pol-TCMS line under HT/LT conditions and increased our understanding of high-temperature-induced anther developmental abnormalities, which may help researchers utilize TCMS in the two-line breeding of Brassica plants.
温敏雄性不育（TMS）是一种受基因型与环境相互作用影响的可遗传农艺性状。植物的花药由各种特化细胞组成，每个细胞在植物繁殖中发挥不同作用。在油菜（甘蓝型油菜）中，波里马（pol）温敏细胞质雄性不育（TCMS）在两系育种中广泛应用，因为其育性在特定温度下可部分恢复。与低温（允许温度，LT，16℃）相比，pol-TCMS系在高温（限制温度，HT，25℃）下花药发育异常且花粉败育。然而，不同花药细胞类型对高温的响应以及在此条件下基因的动态调控仍 largely 未知。
我们展示了甘蓝型油菜早期发育花芽组织响应高温的首个单细胞转录组图谱。通过 LT 和 HT 处理条件下的已知标记基因，我们鉴定出 8 种细胞类型和 17 个转录上不同的细胞簇。在 HT 条件下，观察到不同细胞簇的基因表达模式发生变化，各种细胞类型中下调基因的数量超过上调基因。拟时间轨迹分析表明，高温强烈影响早期雄蕊/花药组织细胞的发育。结合 snRNA-seq、WGCNA 和批量 RNA-seq 结果，我们发现许多转录因子在对高温的响应中起关键作用，尤其是热响应家族基因。
我们的研究揭示了 pol-TCMS 系在 HT/LT 条件下花芽组织的转录调控网络，并增进了我们对高温诱导花药发育异常的理解，这可能有助于研究人员在油菜植物的两系育种中利用 TCMS。
