The floral transition is a critical developmental switch in plants, and has profound effects on the flower production and yield. Magnolia × soulangeana ‘Changchun’ is known as a woody ornamental plant, which can bloom in spring and summer, respectively. In this study, anatomical observation, physiological measurement, transcriptome, and small RNA sequencing were performed to investigate potential endogenous regulatory mechanisms underlying floral transition in ‘Changchun’. Transition of the shoot apical meristem from vegetative to reproductive growth occurred between late April and early May. During this specific developmental process, a total of 161,645 unigenes were identified, of which 73,257 were significantly differentially expressed, while a number of these two categories of miRNAs were 299 and 148, respectively. Further analysis of differentially expressed genes (DEGs) revealed that gibberellin signaling could regulate floral transition in ‘Changchun’ in a DELLA-dependent manner. In addition, prediction and analysis of miRNA targeted genes suggested that another potential molecular regulatory module was mediated by the miR172 family and other several novel miRNAs (Ms-novel_miR139, Ms-novel_miR229, and Ms-novel_miR232), with the participation of up- or down-regulating genes, including MsSVP, MsAP2, MsTOE3, MsAP1, MsGATA6, MsE2FA, and MsMDS6. Through the integrated analysis of mRNA and miRNA, our research results will facilitate the understanding of the potential molecular mechanism underlying floral transition in ‘Changchun’, and also provide basic experimental data for the plant germplasm resources innovation in Magnolia.

花期过渡是植物中至关重要的发育转换，对花的产量和产量有深远的影响。玉兰 ×  soulangeana“长春”被称为木本观赏植物，可以分别在春季和夏季开花。在这项研究中，进行了解剖学观察，生理测量，转录组和小RNA测序，以研究“长春”花卉过渡的潜在内源调控机制。茎尖分生组织从营养生长到生殖生长的转变发生在4月下旬至5月初之间。在这一特定的发育过程中，共鉴定出161,645个单基因，其中73,257个显着差异表达，而这两类miRNA的数量分别为299和148。差异表达基因（DEGs）的进一步分析表明，赤霉素信号传导可以以“ DELLA”依赖性方式调节“长春”中的花期过渡。MsSVP，MsAP2，MsTOE3，MsAP1，MsGATA6，MsE2FA和MsMDS6。通过对mRNA和miRNA的综合分析，我们的研究结果将有助于人们了解“长春”花卉过渡的潜在分子机制，并为玉兰植物种质资源创新提供基础实验数据。