Abstract：
Maize develops separate ear and tassel inflorescences with initially similar morphology but ultimately different architecture and sexuality. The detailed regulatory mechanisms underlying these changes still remain largely unclear. In this study, through analyzing the time-course meristem transcriptomes and floret single-cell transcriptomes of ear and tassel, we revealed the regulatory dynamics and pathways underlying inflorescence development and sex differentiation. We identified 16 diverse gene clusters with differential spatiotemporal expression patterns and revealed biased regulation of redox, programmed cell death, and hormone signals during meristem differentiation between ear and tassel. Notably, based on their dynamic expression patterns, we revealed the roles of two RNA-binding proteins in regulating inflorescence meristem activity and axillary meristem formation. Moreover, using the transcriptional profiles of 53 910 single cells, we uncovered the cellular heterogeneity between ear and tassel florets. We found that multiple signals associated with either enhanced cell death or reduced growth are responsible for tassel pistil suppression, while part of the gibberellic acid signal may act non-cell-autonomously to regulate ear stamen arrest during sex differentiation. We further showed that the pistil-protection gene SILKLESS 1 (SK1) functions antagonistically to the known pistil-suppression genes through regulating common molecular pathways, and constructed a regulatory network for pistil-fate determination. Collectively, our study provides a deep understanding of the regulatory mechanisms underlying inflorescence development and sex differentiation in maize, laying the foundation for identifying new regulators and pathways for maize hybrid breeding and improvement.
摘要：
玉米发育独立的穗和流苏花序，最初具有相似的形态，但最终具有不同的结构和性。这些变化背后的详细监管机制仍在很大程度上不清楚。在这项研究中,通过分析耳朵和流苏的分生组织转录组和小花单细胞转录组，我们揭示了花序发育和性别分化的调节动力学和途径。我们确定了16个不同的基因簇，具有不同的时空表达模式，并揭示了氧化还原的偏倚调节，耳朵和流苏之间分生组织分化的程序性细胞死亡和激素信号。特别是,根据他们的动态模式，我们揭示了两种RNA结合蛋白在调节花序分生组织活性和腋生分生组织形成中的作用。此外，使用53,910个单细胞的转录谱，我们发现了耳朵和流苏小花之间的细胞异质性。我们发现，与细胞死亡增强或生长减少相关的多种信号是抑制雄蕊的原因。而部分GA信号可能是非细胞自主作用，以调节性别分化过程中的雄蕊停滞。我们进一步表明，雌蕊保护基因SILKLESS1（SK1）通过调节常见的分子途径拮抗已知的雌蕊抑制基因，并构建了雌蕊命运决定的调控模型。总的来说，我们的研究为玉米花序发育和性别分化的调节机制提供了深刻的理解，为确定玉米杂交育种和改良的新调控因子和途径奠定基础。
