Most plants do not gather nutrients from the soil entirely on their own. Many form partnerships with microscopic fungi that grow inside their roots and extend into the surrounding soil. These partnerships, known as arbuscular mycorrhizal symbioses, help plants access nutrients, especially phosphorus. In return, the fungi receive carbon-rich compounds from the plants. But how does a plant coordinate the many signals needed to build and maintain this exchange?
A research team led by associate professor Shu-Yi Yang at National Taiwan University has uncovered an important part of the answer in rice. Their study, published in Nature Communications, identifies a protein called IDD7 as a key regulator of the plant's response to beneficial fungi.
When the fungi enter rice roots, they form finely branched structures called arbuscules inside certain root cells. These structures provide a specialized interface where the two partners exchange resources. The researchers found that IDD7 becomes strongly expressed in cells containing arbuscules. Rice plants lacking functional IDD7 showed impaired fungal colonization and arbuscule development, while restoring the gene rescued the defects. These findings show that IDD7 is important for the partnership to develop normally.
The team then investigated how IDD7 works. They discovered that it interacts with two other regulatory proteins: SLR1, which is associated with plant growth-hormone signaling, and PHR2, a major regulator of responses to phosphorus availability. Together, these proteins enhanced the activity of genes involved in fungal accommodation and nutrient exchange. The researchers also showed that IDD7 can bind DNA regions associated with genes important for the symbiosis.
Click here to see more...