Table_1_Whole-transcriptome analysis of differentially expressed genes between ray and disc florets and identification of flowering regulatory genes in Chrysanthemum morifolium.DOCX

Chrysanthemum morifolium has ornamental and economic values. However, there has been minimal research on the morphology of the chrysanthemum florets and related genes. In this study, we used the leaves as a control to screen for differentially expressed genes between ray and disc florets in chrysanthemum flowers. A total of 8,359 genes were differentially expressed between the ray and disc florets, of which 3,005 were upregulated and 5,354 were downregulated in the disc florets. Important regulatory genes that control flower development and flowering determination were identified. Among them, we identified a TM6 gene (CmTM6-mu) that belongs to the Class B floral homeotic MADS-box transcription factor family, which was specifically expressed in disc florets. We isolated this gene and found it was highly similar to other typical TM6 lineage genes, but a single-base deletion at the 3′ end of the open reading frame caused a frame shift that generated a protein in which the TM6-specific paleoAP3 motif was missing at the C terminus. The CmTM6-mu gene was ectopically expressed in Arabidopsis thaliana. Petal and stamen developmental processes were unaffected in transgenic A. thaliana lines; however, the flowering time was earlier than in the wild-type control. Thus, the C-terminal of paleoAP3 appears to be necessary for the functional performance in regulating the development of petals or stamens and CmTM6-mu may be involved in the regulation of flowering time in chrysanthemum. The results of this study will be useful for future research on flowering molecular mechanisms and for the breeding of novel flower types.

菊花（Chrysanthemum morifolium）兼具观赏与经济价值。然而目前针对菊花小花形态及其相关基因的研究仍较为匮乏。本研究以叶片作为对照，筛选菊花舌状花与管状花之间的差异表达基因。最终共获得8359个差异表达基因，其中管状花中上调表达3005个，下调表达5354个。本研究鉴定到一批调控花发育与开花决定的关键基因，其中包括一个隶属于B类花同源异型MADS-box转录因子家族的TM6基因（CmTM6-mu），该基因特异性在管状花中表达。我们对该基因进行克隆后发现，其与其他典型TM6谱系基因相似度极高，但开放阅读框3'端存在一处单碱基缺失，引发移码突变，最终导致编码蛋白的C末端缺失了TM6特有的paleoAP3基序。将CmTM6-mu基因在拟南芥（Arabidopsis thaliana）中进行异位表达后，转基因拟南芥株系的花瓣与雄蕊发育未受影响，但开花时间早于野生型对照。由此可见，paleoAP3基序的C末端区域对于调控花瓣或雄蕊发育的功能发挥是必需的，而CmTM6-mu可能参与调控菊花的开花时间。本研究结果可为未来开花分子机制研究及新型花型育种提供参考依据。