LpBPM5.6 regulates turfgrass architecture by influencing LpARG1 stability in perennial ryegrass

The improvement of plant architecture has historically driven the "Green Revolution," leading to substantial increases in cereal yields. However, the architectural requirements for turfgrass differ from those of cereals. Despite its importance, our understanding of the mechanisms that regulate plant architecture in turfgrass remains limited. In this study, we identified that Lolium perenne BTB/POZ-MATH5.6s (LpBPM5.6) plays a crucial role in shaping the ideal turfgrass architecture by influencing the stability of ALTERED RESPONSE TO GRAVITY 1 (LpARG1) in perennial ryegrass. The phenotypes of LpBPM5.6-overexpressing and RNA interference transgenic seedlings revealed that knocking down LpBPM5.6 results in an ideal turfgrass architecture characterized by reduced plant height, increased tillering, and fewer fibrous roots. Through yeast 2-hybrid library screening, as well as subsequent pull-down, luciferase complementation imaging, and co-immunoprecipitation techniques, we demonstrated that LpBPM5.6 interacts with LpARG1. Protein degradation assays indicated that LpBPM5.6 regulates the degradation of LpARG1. Additionally, microscopic observations showed that LpBPM5.6 and LpARG1 affect the trafficking of PIN1, thereby influencing auxin transport and turfgrass architecture. This study elucidates how LpBPM5.6 regulates turfgrass architecture by modulating the stability of LpARG1, providing insights into the genetic mechanisms underlying the ideal plant architecture for turfgrass.