Many plants form symbiotic relationships with arbuscular mycorrhiza (known as arbuscular mycorrhizal symbiosis or AMS) which helps scavenge phosphate from soils. However, while it is known that this interaction is driven by plant-produced strigolactones (SLs), which stimulate fungal colonisation, and by specific phosphate transporter genes, little more is known about understanding the genetic factors which underly these processes.
Now researchers from Zhejiang University and the Chinese Academy of Agricultural Sciences have revealed the genetic and chemical factors which coordinate AMS and phosphate uptake in tomato. Using gene editing, protein interaction assays, and chromatin analyses, the team showed that SlPIF4 represses genes critical to symbiosis, while SlDELLA counteracts its activity, facilitating root-fungal collaboration. The findings shed light on a finely balanced signalling network with major implications for sustainable agriculture.
“This study uncovers a beautifully orchestrated mechanism at the root-fungus interface,” said Dr Yanhong Zhou, corresponding author of the paper. “We now understand that SlPIF4 acts as a repressor, while SlDELLA steps in as a molecular safeguard to ensure the plant can fully benefit from symbiosis. This balance between repression and release could be key to improving how crops use nutrients, especially under stress conditions.”
The team believe that this information opens new doors for breeding crops with enhanced nutrient-use efficiency. By fine-tuning the SlDELLA–SlPIF4 interaction, it may be possible to engineer tomato varieties that form stronger partnerships with soil fungi and absorb phosphorus more effectively—reducing reliance on chemical fertilisers.