D14 receptor binds and stabilizes transcription factor PHR1 in plants
Biologists identified a direct molecular link between strigolactone perception and phosphate starvation responses in plant models.
Biologists have revealed the molecular mechanism coordinating phosphate starvation responses and strigolactone signaling in plants, according to a study published in Science Advances science.org
Science Advancesscience.orgOpen source ↗. The researchers demonstrated that the strigolactone receptor DWARF14 (D14) directly interacts with the transcription factor PHR1 in a strigolactone-dependent manner, positioning PHR1 directly downstream of hormone perception.
Receptor Interaction and Protein Stability
The binding between D14 and PHR1 promotes the dimerization of the transcription factor, enhances its transcriptional activation activity, and protects it from ubiquitination-mediated degradation. Experiments demonstrated that the resulting D14-PHR1 complex directly binds to and up-regulates specific target genes, including the strigolactone biosynthesis gene MAX3 and genes responsible for anthocyanin biosynthesis. This pathway leads to suppressed shoot branching, reduced hypocotyl elongation, and increased anthocyanin accumulation under low-phosphate conditions.
Root Architecture and Signal Integration
The team found that PHR1 is essential for strigolactone-induced anthocyanin accumulation and lateral root development during phosphate deficiency. While exogenous strigolactones typically promote lateral root formation under low phosphorus and inhibit it under high phosphorus, phr1 mutants showed lateral root inhibition under both conditions. Furthermore, the D14-PHR1 module activates downstream regulatory factors, including LBD genes and HB23, to control root architecture. The authors concluded that phosphate starvation signaling integrates with strigolactones via two parallel mechanisms: metabolic control of hormone biosynthesis and direct amplification of PHR1 activity through D14 complex formation.
