For a flowering plant, the transition from vegetative stage to reproductive growth is probably the most critical developmental switch. In the model plant Arabidopsis thaliana , the product of BBX7 , group II member of BBX family, acts to delay floral transition. In this study, a presumed chrysanthemum homolog of a second group gene AtBBX8 , designated CmBBX8 , had been isolated and characterized. The transcription of CmBBX8 followed a diurnal rhythm as the chrysanthemum floral transition regulator. Overexpression of CmBBX8 accelerated flowering, while its (artificial microRNAs) amiR‐enabled knockdown delayed flowering in plants grown under both long‐ and short‐day conditions. Global expression analysis revealed that genes associated with photoperiod were down‐regulated in amiR‐CmBBX8 lines compared with the wild type, which were verified to be up‐regulated in overexpressing lines (OX‐CmBBX8 ) by RT‐PCR. A number of in vitro assays were used to show that CmBBX8 targets CmFTL1 . Furthermore, the function of CmFTL1 as a floral inducer under long‐day conditions was confirmed by the behaviour of engineered summer‐flowering chrysanthemum plants. The conclusion is that the BBX8‐FT regulatory module is an important determinant of reproductive development in summer‐flowering chrysanthemum.

中文翻译：

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CmBBX8通过直接在夏季菊花中靶向CmFTL1来加速开花。

对于开花植物，从营养阶段到生殖生长的过渡可能是最关键的发育转换。在模型植物拟南芥中，BBX家族II类成员BBX7的产物可延缓花期过渡。在这项研究中，第二组基因AtBBX8（称为CmBBX8）的假定的菊花同源物已被分离和鉴定。CmBBX8的转录遵循菊花节律的昼夜节律。CmBBX8的过表达加速开花，而其（人工microRNA）amiR激活的敲低则延迟了在长日和短日条件下生长的植物的开花。全局表达分析显示，与野生型相比，与光周期相关的基因在amiR‐ CmBBX8系中被下调，而RT‐PCR证实其在过表达系（OX ‐ CmBBX8）中被上调。许多体外试验被用来表明CmBBX8靶向CmFTL1。此外，CmFTL1的功能工程夏花菊花植物的行为证实了其在长时间条件下的花香诱导作用。结论是，BBX8-FT调节模块是夏季开花菊花生殖发育的重要决定因素。