Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University, Beijing 100193, China.
J Exp Bot. 2010 Jun;61(11):3069-78. doi: 10.1093/jxb/erq133. Epub 2010 May 17.
Previous studies of highly branched mutants in pea (rms1-rms5), Arabidopsis thaliana (max1-max4), petunia (dad1-dad3), and rice (d3, d10, htd1/d17, d14, d27) identified strigolactones or their derivates (SLs), as shoot branching inhibitors. This recent discovery offers the possibility of using SLs to regulate branching commercially, for example, in chrysanthemum, an important cut flower crop. To investigate this option, SL physiology and molecular biology were studied in chrysanthemum (Dendranthema grandiflorum), focusing on the CCD8/MAX4/DAD1/RMS1/D10 gene. Our results suggest that, as has been proposed for Arabidopsis, the ability of SLs to inhibit bud activity depends on the presence of a competing auxin source. The chrysanthemum SL biosynthesis gene, CCD8 was cloned, and found to be regulated in a similar, but not identical way to known CCD8s. Expression analyses revealed that DgCCD8 is predominantly expressed in roots and stems, and is up-regulated by exogenous auxin. Exogenous SL can down-regulate DgCCD8 expression, but this effect can be overridden by apical auxin application. This study provides evidence that SLs are promising candidates to alter the shoot branching habit of chrysanthemum.
先前对豌豆（rms1-rms5）、拟南芥（max1-max4）、矮牵牛（dad1-dad3）和水稻（d3、d10、htd1/d17、d14、d27）中高度分支突变体的研究鉴定出了独脚金内酯或其衍生物（SLs），它们是分枝抑制剂。这一最新发现为利用 SLs 来调节商业分枝提供了可能，例如在菊花（Dendranthema grandiflorum）这种重要的切花作物中。为了研究这种选择，对菊花中的 SL 生理学和分子生物学进行了研究，重点研究了 CCD8/MAX4/DAD1/RMS1/D10 基因。我们的研究结果表明，正如拟南芥所提出的，SL 抑制芽活性的能力取决于竞争生长素源的存在。菊花 SL 生物合成基因 CCD8 被克隆，并发现其表达调控方式与已知的 CCD8 相似，但不完全相同。表达分析表明，DgCCD8 主要在根和茎中表达，并受到外源生长素的上调。外源 SL 可以下调 DgCCD8 的表达，但顶端生长素的应用可以克服这种影响。本研究提供了证据表明，SLs 是改变菊花分枝习性的有前途的候选物。
