Inhibition of shoot branching in Arabidopsis by the artificially biosynthesized canonical strigolactone.

Strigolactones (SLs) are apocarotenoid plant hormones that regulate shoot branching. The natural SLs can be divided into 2 groups, canonical and noncanonical SLs, according to those chemical structures. In a model plant, Arabidopsis thaliana, it has been thought to produce only noncanonical SLs. Moreover, in rice, it was suggested that canonical-SL such as 4-deoxyorobanchol (4DO) does not have a critical role in shoot branching inhibition. In this report, to understand the potential of canonical-SL in the shoot branching inhibition pathway in Arabidopsis, SL biosynthetic genes involved in canonical-SL production in other plant species were individually expressed in Arabidopsis. Our data clearly demonstrate that 5-deoxystrigol, but not 4DO, can inhibit shoot branching in Arabidopsis. Moreover, the results confirmed the important role of CLA methyltransferase in the shoot branching inhibition pathway in Arabidopsis.