Dt1 interacts with HB40 to affect lateral root primordium development by regulating CDC48 in soybean.

Roots act as the plants' primary determinants of the uptake of water and nutrients, while the root structure largely depends on the repeated formation of new lateral roots (LR). Lateral root primordium (LRP) formation defines the organization and function of LRs. Therefore, lateral root formation is quite related to proper LRP morphogenesis to a great extent. Here, we identified the Arabidopsis TERMINAL FLOWER1 (TFL1) ortholog gene Dt1, which mediates soybean LRP development. The dt1 knock-out mutants showed reduced LRs with decreased LRPs. Further experiments proved that Dt1 interacted with the homeodomain-leucine zipper (HD-Zip) I family transcription factor HB40 to regulate Cell Division Control protein 48 (CDC48) expression and thus affect soybean LRP development. In summary, this study identified the Dt1-HB40-CDC48 regulatory modules to intricately control LRP development.