Scientists point out data on symbiosis between plants and fungi

Research from the Boyce Thompson Institute reveals the vital role of proteins in the nutrition of arbuscular mycorrhizal fungi and opens the way for advances in sustainable agriculture

26.01.2024 | 15:02 (UTC -3)
Cultivar Magazine

Researchers at the Boyce Thompson Institute (BTI) studied the symbiotic relationship between plants and arbuscular mycorrhizal (AM) fungi. The relationship involves complex and critical exchange of nutrients. And it was considered essential for the survival of the fungus and highly beneficial for the plant.

The focus of the study published in the journal "Science" is two proteins, CKL1 and CKL2. These proteins are active only in root cells containing AM fungi. They belong to a larger family of proteins known as CKLs. Its functions in the plant are not yet fully understood.

Sergey Ivanov, postdoctoral researcher at BTI and first author of the study, explained that the CKL1 and CKL2 proteins have evolved to play a different role than CDKs, their closest relative proteins. While CDKs control the plant cell cycle and are located in the cell nucleus, CKLs are tethered to root cell membranes, including a membrane that surrounds the fungus.

Scientists have discovered that CKL proteins are crucial for the survival of fungi inside plant roots. They play a fundamental role in controlling the flow of lipids (fats) from the plant to the fungus. This process is essential for the nutrition of the fungus. Without these proteins, key genes that manage lipid transfer are not activated, leaving the fungi without food.

The research also revealed a complex network of interactions involving several receptor protein kinases. One of these kinases is known for its role in allowing the AM fungus to penetrate the outer layer of the root. The researchers found that this same kinase adopts a new role deeper in the root, where it associates with CKL proteins, potentially to initiate the flow of lipids into the fungus.

Interestingly, while CKL proteins are vital for controlling lipid flux, they do not manage the entire lipid symbiotic pathway. Instead, they control genes responsible for the beginning and end of this pathway. Meanwhile, a key protein that operates midway through this pathway, RAM2, is activated by a different regulator, RAM1. For large-scale lipid production to occur, both the CKL and RAM1 pathways must be active.

Maria Harrison, professor at BTI and senior author of the study, commented that lipids are costly to the plant. Therefore, dual regulatory mechanisms can ensure that lipid supply is tightly controlled. This may be a safeguard against exploitation by fungal pathogens.

Harrison also highlighted that, in an agricultural context, taking advantage of this natural symbiosis can lead to crops that are more efficient at absorbing nutrients and more resilient to environmental stressors.

More information at DOI:10.1126/science.ade1124

Mosaic Biosciences March 2024