Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, and College of Life Sciences, Capital Normal University, Beijing 100048, China.
Max Planck Institute for Plant Breeding Research, Cologne, D-50829, Germany.
Plant Cell. 2021 May 5;33(3):475-491. doi: 10.1093/plcell/koaa043.
Photoperiod plays a key role in controlling the phase transition from vegetative to reproductive growth in flowering plants. Leaves are the major organs perceiving day-length signals, but how specific leaf cell types respond to photoperiod remains unknown. We integrated photoperiod-responsive chromatin accessibility and transcriptome data in leaf epidermis and vascular companion cells of Arabidopsis thaliana by combining isolation of nuclei tagged in specific cell/tissue types with assay for transposase-accessible chromatin using sequencing and RNA-sequencing. Despite a large overlap, vasculature and epidermis cells responded differently. Long-day predominantly induced accessible chromatin regions (ACRs); in the vasculature, more ACRs were induced and these were located at more distal gene regions, compared with the epidermis. Vascular ACRs induced by long days were highly enriched in binding sites for flowering-related transcription factors. Among the highly ranked genes (based on chromatin and expression signatures in the vasculature), we identified TREHALOSE-PHOSPHATASE/SYNTHASE 9 (TPS9) as a flowering activator, as shown by the late flowering phenotypes of T-DNA insertion mutants and transgenic lines with phloem-specific knockdown of TPS9. Our cell-type-specific analysis sheds light on how the long-day photoperiod stimulus impacts chromatin accessibility in a tissue-specific manner to regulate plant development.
光周期在控制开花植物从营养生长向生殖生长的转变中起着关键作用。叶片是感知日照长度信号的主要器官，但特定叶片细胞类型如何响应光周期仍不清楚。我们通过将标记在特定细胞/组织类型中的核与使用测序和 RNA 测序进行转座酶可及染色质检测的测定相结合，整合了拟南芥叶片表皮和维管束伴胞中对光周期有反应的染色质可及性和转录组数据。尽管有很大的重叠，但血管和表皮细胞的反应不同。长日照主要诱导可及染色质区域（ACRs）；与表皮相比，在血管中，更多的 ACRs 被诱导，并且这些 ACRs位于更远的基因区域。长日照诱导的血管 ACRs 富含与开花相关转录因子的结合位点。在根据血管中的染色质和表达特征排名靠前的基因中，我们确定 TREHALOSE-PHOSPHATASE/SYNTHASE 9（TPS9）是一种开花激活剂，如 T-DNA 插入突变体和具有韧皮部特异性 TPS9 敲低的转基因系的晚开花表型所示。我们的细胞类型特异性分析阐明了长日光周期刺激如何以组织特异性的方式影响染色质可及性，从而调节植物发育。
