CBGP researchers discover a gene that regulates plants’ disease resistance and cell wall composition

Plant cell wall is a complex cell structure that surrounds all plant cells. This structure plays a very important role as a physical barrier that pathogens must overcome to colonize the plant and cause diseases. The cell wall is a dynamic structure that is modified during the infection process or in response to environmental stresses, altering its structural integrity. These changes in the integrity of the cell wall cause the release of molecules (called DAMPs, from Damage Associated Molecular Patterns) that are perceived by the plant triggering immunity and defense responses.

Researchers at the Centre for Plant Biotechnology and Genomics (CBGP, UPM-INIA) have recently described in the journal of "Molecular Plant-Microbe Interactions" a previously unknown function of ARR6 gene from Arabidopsis thaliana. Until now, ARR6 was believed to act exclusively as a mediator of the plant's hormonal responses. However, Dr. Antonio Molina's group has shown that ARR6 is actually a regulator of cell wall composition and of the disease resistance responses of plants against different pathogens causing important diseases. In this work, it has been shown that Arabidopsis plants that have a non-functional version of the ARR6 gene in their genome are more resistant to Plectosphaerella cucumerina fungus, but develop more rapidly and intensely the disease caused by the bacterium Ralstonia solanacearum. On the contrary, plants that display high levels of ARR6 are more resistant to the bacteria, but more susceptible to the fungus. By combining different biochemical approaches, CBGP researchers managed to purify carbohydrate-like components from the walls of ARR6-deficient plants. These molecules could be responsible for the differential regulation of resistance responses to fungi and bacteria, pointing to an interesting interaction between wall composition, innate immunity signaling and disease resistance. This results support the potential use of formulations based cell wall-derived molecules triggering immune responses as more sustainable and effective treatment to regulate crops disease resistance and to mitigate crop losses caused by pathogen and pests.