Find in Library

Strigolactones (SLs) regulate plant shoot development by inhibiting axillary bud growth and branching. However, the role of SLs in wintersweet (<i>Chimonanthus praecox</i>) shoot branching remains unknown. Here, we identified and isolated two wintersweet genes, <i>CCD7</i> and <i>CCD8</i>, involved in the SL biosynthetic pathway. Quantitative real-time PCR revealed that <i>CpCCD7</i> and <i>CpCCD8</i> were down-regulated in wintersweet during branching. When new shoots were formed, expression levels of <i>CpCCD7</i> and <i>CpCCD8</i> were almost the same as the control (un-decapitation). <i>CpCCD7</i> was expressed in all tissues, with the highest expression in shoot tips and roots, while <i>CpCCD8</i> showed the highest expression in roots. Both CpCCD7 and CpCCD8 localized to chloroplasts in <i>Arabidopsis</i>. <i>CpCCD7</i> and <i>CpCCD8</i> overexpression restored the phenotypes of branching mutant <i>max3-9</i> and <i>max4-1</i>, respectively. <i>CpCCD7</i> overexpression reduced the rosette branch number, whereas <i>CpCCD8</i> overexpression lines showed no phenotypic differences compared with wild-type plants. Additionally, the expression of <i>AtBRC1</i> was significantly up-regulated in transgenic lines, indicating that two <i>CpCCD</i> genes functioned similarly to the homologous genes of the Arabidopsis. Overall, our study demonstrates that <i>CpCCD7</i> and <i>CpCCD8</i> exhibit conserved functions in the CCD pathway, which controls shoot development in wintersweet. This research provides a molecular and theoretical basis for further understanding branch development in wintersweet.