Fu Jianxin, Yang Liwen, Dai Silan
Beijing Key Laboratory of Ornamental Plants Germplasm Innovation and Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China.
Mol Genet Genomics. 2015 Jun;290(3):1039-54. doi: 10.1007/s00438-014-0977-3. Epub 2014 Dec 19.
The CONSTANS (CO) and CONSTANS-like (COL) genes play key roles in the photoperiodic flowering pathways, and studying their functions can elucidate the molecular mechanisms underlying flowering control in photoperiod-regulated plants. We identified eleven COL genes (ClCOL1-ClCOL11) in Chrysanthemum lavandulifolium and divided them into three groups that are conserved among the flowering plants based on phylogenetic analysis. Most of the ClCOL genes are primarily expressed in the leaf and shoot apices, except for ClCOL6-ClCOL9, which belong to Group II. The expression levels of ClCOL4-ClCOL5 and ClCOL7-ClCOL8 are up-regulated under inductive short-day (SD) conditions, whereas ClCOL6 is down-regulated under inductive SD conditions. The ClCOL genes exhibit four different diurnal rhythm expressions (Type I-Type IV). The Type I genes (ClCOL4-ClCOL5) are highly transcribed under light. The Type II genes (ClCOL1-ClCOL2, ClCOL10) display increased expression in darkness and are rapidly suppressed under light. Transcripts of ClCOL6-ClCOL9 and ClCOL11, belonging to Type III, are abundant in the late light period or at the beginning of the dark period. ClCOL3 belongs to Type IV, with high expression in the early light period and dark period. The peak expression levels of ClCOL4-ClCOL6 are decreased and postponed in the non-inductive night break (NB) and under long-day (LD) conditions, indicating that those genes may play an essential role in the flowering regulation of C. lavandulifolium. The overexpression of ClCOL5 promotes the flowering of Arabidopsis grown under LD conditions, suggesting that ClCOL5 may function as a flowering enhancer in C. lavandulifolium. This study will be useful not only for the study of the C. lavandulifolium photoperiod-dependent flowering process but also for the genetic manipulation of flowering time-related genes to change the flowering time in the chrysanthemum.
CONSTANS（CO）和CONSTANS类（COL）基因在光周期开花途径中起关键作用，研究它们的功能可以阐明光周期调控植物中开花控制的分子机制。我们在野菊花中鉴定出11个COL基因（ClCOL1-ClCOL11），并根据系统发育分析将它们分为开花植物中保守的三组。除了属于第二组的ClCOL6-ClCOL9外，大多数ClCOL基因主要在叶片和茎尖中表达。ClCOL4-ClCOL5和ClCOL7-ClCOL8的表达水平在诱导短日（SD）条件下上调，而ClCOL6在诱导SD条件下下调。ClCOL基因表现出四种不同的昼夜节律表达（I型-IV型）。I型基因（ClCOL4-ClCOL5）在光照下高度转录。II型基因（ClCOL1-ClCOL2，ClCOL10）在黑暗中表达增加，并在光照下迅速受到抑制。属于III型的ClCOL6-ClCOL9和ClCOL11的转录本在光照后期或黑暗期开始时丰富。ClCOL3属于IV型，在光照初期和黑暗期高表达。ClCOL4-ClCOL6的峰值表达水平在非诱导性夜间中断（NB）和长日（LD）条件下降低并延迟，表明这些基因可能在野菊花的开花调控中起重要作用。ClCOL5的过表达促进了在LD条件下生长的拟南芥的开花，表明ClCOL5可能在野菊花中作为开花增强子发挥作用。这项研究不仅将有助于研究野菊花光周期依赖的开花过程，而且对于开花时间相关基因的遗传操作以改变菊花的开花时间也将是有用的。
