Hu Bin, Yang Na, Zhou Zaihui, Shi Xiangyu, Qin Yunxia, Fang Yongjun, Long Xiangyu
National Key Laboratory for Tropical Crop Breeding, Ministry of Agriculture Key Laboratory of Biology and Genetic Resources of Rubber Tree, State Key Laboratory Breeding Base of Cultivation and Physiology for Tropical Crops, Rubber Research Institute, Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Haikou, China.
National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China.
Front Plant Sci. 2024 Jan 24;15:1337451. doi: 10.3389/fpls.2024.1337451. eCollection 2024.
The molecular mechanisms underlying the initiation of natural rubber synthesis and laticifer differentiation have not been fully elucidated. In this study, we conducted a time-series transcriptome analysis of five rubber tree tissues at four stages of seed germination. A total of 161,199 DEGs were identified between the two groups, including most 16,673 DEGs (A3 vs B3 and A3 vs C3) and lest 1,210 DEGs (C2 vs D2). We found that the maturation of the seed is accompanied by the formation of laticifer cells in cotyledon. Meanwhile, the analysis of hormones related genes expression may provide effective clues for us to promote the differentiation of laticifer cells in seeds by hormones in the future. In this study, hormone-related gene enrichment analyses revealed that IAA, GA, and CTK were activated in laticifer containing tissues. Similarly, GO and GEGG analysis showed that hormone pathways, especially the auxin pathway, are enriched. Gene expression clustering was analyzed using the short time-series expression miner (STEM), and the analysis revealed four distinct trends in the gene expression profiles. Moreover, we enriched transcription factor (TF) enrichment in cotyledon and embryonic axis tissues, and the MYB type exhibited the most significant difference. Furthermore, our findings revealed that genes related to rubber synthesis exhibited tissue-specific expression patterns during seed germination. Notably, key genes associated with rubber biosynthesis, specifically () and (), exhibited significant changes in expression in cotyledon and embryonic axis tissues, suggesting synchronous rubber synthesis with seed germination. Our staining results reveled that laticifer cells were exits in the cotyledon before seed imbibition stage. In conclusion, these results lay the foundation for exploring the molecular mechanisms underlying laticifer differentiation and rubber synthesis during seed germination, deepening our understanding of the initiation stages of rubber biosynthesis and laticifer differentiation.
天然橡胶合成起始和乳管分化的分子机制尚未完全阐明。在本研究中，我们对橡胶树种子萌发四个阶段的五个组织进行了时间序列转录组分析。两组之间共鉴定出161,199个差异表达基因（DEGs），其中最多有16,673个DEGs（A3与B3以及A3与C3），最少有1,210个DEGs（C2与D2）。我们发现种子成熟伴随着子叶中乳管细胞的形成。同时，对激素相关基因表达的分析可能为我们未来通过激素促进种子中乳管细胞的分化提供有效线索。在本研究中，激素相关基因富集分析表明，IAA、GA和CTK在含有乳管的组织中被激活。同样，GO和GEGG分析表明激素途径，尤其是生长素途径，被富集。使用短时间序列表达挖掘器（STEM）分析基因表达聚类，分析揭示了基因表达谱中的四种不同趋势。此外，我们在子叶和胚轴组织中富集了转录因子（TF），其中MYB类型表现出最显著的差异。此外，我们的研究结果表明，与橡胶合成相关的基因在种子萌发过程中表现出组织特异性表达模式。值得注意的是，与橡胶生物合成相关的关键基因，特别是（）和（），在子叶和胚轴组织中的表达发生了显著变化，表明橡胶合成与种子萌发同步。我们的染色结果显示，在种子吸胀阶段之前，子叶中就存在乳管细胞。总之，这些结果为探索种子萌发过程中乳管分化和橡胶合成的分子机制奠定了基础，加深了我们对橡胶生物合成和乳管分化起始阶段的理解。
