Strigolactones have been described to have an impact on lateral root and root hair formation (Kapulnik et al., 2011; Mayzlish‐Gati et al., 2012), factors that influence plant nutrition. We investigated whether PDR1 OE plants can produce a higher biomass than the wild‐type not only because of faster mycorrhization but also because of altered root structures that are possibly more efficient in nutrient uptake. Indeed, on Claymin in the absence of mycorrhiza, PDR1OE exhibit a higher biomass compared with the wild type (Fig. 4a–f). Using X‐ray computed tomography (see Methods S1 and Table S1) we screened root volumes, surfaces and the amounts of lateral roots on clay+, where we observed a significant increase of PDR1 OE biomass. At 6 wag the tomography did not reveal significant differences between wild‐type and PDR1 OE plants (Fig. S6a–c; Movies S1, S2). By contrast, at 8 wag, significantly more lateral roots could be observed in PDR1 OE plants (Fig. 6a). Interestingly, this difference was also visible in the absence of AMF (Fig. 6b,c; Movies S3, S4), while a significant increase in total root volume and surface was only measured when plants were grown with AMF, suggesting that without the input of AMF, lateral root growth was initiated but did not proceed as quickly. On clay+, a dense disc of lateral roots was present close to the soil surface in PDR1 OE plants, at a depth of 2–4 cm, but not in the wild‐type (Fig. 6d,e). Shallow roots are known to play an important role in nutrient uptake, as in several soils this is the most nutrient‐rich region (Liao et al., 2001; Lynch, 2013). Therefore, we suggest that PDR1 OE, in the presence of AMF, might also have an advantage by better scavenging surface‐close nutrients. These results show that the induction of lateral roots is linked to the mis‐regulation of PDR1 expression and the consequent SL redistribution and not only to a higher rate of mycorrhization. Interestingly, 3‐wk‐old PDR1 OE seedlings grown under sterile conditions also have a higher number of lateral roots than wild‐type seedlings (Fig. 7a). This result confirms that PDR1 overexpression induces lateral roots independently of the growth substrate and of symbioses with soil microbes.