<p>Strigolactones （SLs）, which were initially characterized as seed germination stimulants for root parasitic plants about 50 years ago, are now known as symbiotic signals for arbuscular mycorrhizal fungi as well as plant hormones that regulate shoot branching and so on. The discovery of SLs as a new class of plant hormones in 2008 was also significant as an initial characterization of SL biosynthetic mutants, which greatly facilitated its biosynthetic studies. In 2012, an SL-like compound called carlactone （CL） was identified from in vitro biochemical studies using three recombinant proteins of biosynthetic enzymes. The discovery of CL further moved ahead with this research field, and so far the nearly entire picture of the SL biosynthetic pathway has been unveiled. In this review, we will introduce the latest knowledge on the SL biosynthetic pathway as well as current efforts toward the characterization of the bioactive forms of SLs as plant hormones.</p>