College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
College of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China.
Plant Physiol. 2023 Aug 31;193(1):466-482. doi: 10.1093/plphys/kiad292.
Japanese apricot (Prunus mume Sieb. et Zucc.) is a traditional fruit tree with a long history. Multiple pistils (MP) lead to the formation of multiple fruits, decreasing fruit quality and yield. In this study, the morphology of flowers was observed at 4 stages of pistil development: undifferentiated stage (S1), predifferentiation stage (S2), differentiation stage (S3), and late differentiation stage (S4). In S2 and S3, the expression of PmWUSCHEL (PmWUS) in the MP cultivar was significantly higher than that in the single-pistil (SP) cultivar, and the gene expression of its inhibitor, PmAGAMOUS (PmAG), also showed the same trend, indicating that other regulators participate in the regulation of PmWUS during this period. Chromatin immunoprecipitation-qPCR (ChIP-qPCR) showed that PmAG could bind to the promoter and the locus of PmWUS, and H3K27me3 repressive marks were also detected at these sites. The SP cultivar exhibited an elevated level of DNA methylation in the promoter region of PmWUS, which partially overlapped with the region of histone methylation. This suggests that the regulation of PmWUS involves both transcription factors and epigenetic modifications. Also, the gene expression of Japanese apricot LIKE HETEROCHROMATIN PROTEIN (PmLHP1), an epigenetic regulator, in MP was significantly lower than that in SP in S2 to 3, contrary to the trend in expression of PmWUS. Our results showed that PmAG recruited sufficient PmLHP1 to maintain the level of H3K27me3 on PmWUS during the S2 of pistil development. This recruitment of PmLHP1 by PmAG inhibits the expression of PmWUS at the precise time, leading to the formation of 1 normal pistil primordium.
日本甜樱（Prunus mume Sieb. et Zucc.）是一种具有悠久历史的传统果树。多雌蕊（MP）导致多果形成，降低了果实的品质和产量。在这项研究中，观察了 4 个雌蕊发育阶段的花形态：未分化阶段（S1）、预分化阶段（S2）、分化阶段（S3）和晚期分化阶段（S4）。在 S2 和 S3 中，MP 品种中 PmWUSCHEL（PmWUS）的表达明显高于单雌蕊（SP）品种，其抑制剂 PmAGAMOUS（PmAG）的基因表达也表现出相同的趋势，表明在此期间，其他调节剂参与了 PmWUS 的调控。染色质免疫沉淀-qPCR（ChIP-qPCR）表明，PmAG 可以结合 PmWUS 的启动子和基因座，并且在这些位点也检测到 H3K27me3 抑制标记。SP 品种在 PmWUS 启动子区域表现出较高水平的 DNA 甲基化，该区域与组蛋白甲基化区域部分重叠。这表明 PmWUS 的调控涉及转录因子和表观遗传修饰。此外，在 S2 到 S3 期间，MP 中日本甜樱 LIKE HETEROCHROMATIN PROTEIN（PmLHP1）的基因表达明显低于 SP 中的表达，而 PmWUS 的表达趋势相反。我们的结果表明，在雌蕊发育的 S2 期间，PmAG 募集了足够的 PmLHP1 来维持 PmWUS 上 H3K27me3 的水平。PmAG 对 PmLHP1 的募集在精确的时间抑制了 PmWUS 的表达，导致 1 个正常雌蕊原基的形成。
