The plant specific transcription factors CBP60g and SARD1 are targeted by a Verticillium secretory protein VdSCP41 to modulate immunity

Like animals, plants have an immune system to protect themselves from disease. When a plant detects a disease-causing microbe, proteins that serve as master regulators of its immune system activate defense-related genes. Yet some microbes can overcome these defenses and successfully infect plants. Verticillium dahliae is a fungus, found in soil, that infects the roots of many plants – including cotton, tomatoes and potatoes. Infection by this fungus causes the leaves to curl and discolor, and the plant to wilt. The V. dahliae fungus releases, or secretes, nearly 800 proteins during an infection. Yet it remains unknown if and how any of these proteins help the fungus to infect plants. A better understanding of how V. dahliae impairs plant immunity to infect its hosts could give insights into ways to improve plant resistance against this fungus. Now, Qin et al. show that a secreted protein called VdSCP41 promotes V. dahliae infection in both cotton and Arabidopsis plants. Further experiments showed that after leaving the fungus, VdSCP41 enters into the plant’s own cells. Protein-protein interaction and biochemical studies then indicated VdSCP41 associates with a master immune regulator in Arabidopsis called CBP60g. This interaction interferes with CBP60g’s ability to activate the defense-related genes. Now that this role for VdSCP41 has been confirmed, the next step would be to see if targeting it would make plants more resistant to this fungus. One approach would be to genetically engineer plants so that they can specifically shut down, or ‘silence’, the fungal gene that encodes for this protein. Further experiments are required to see whether using this technique – known as host-induced gene silencing (or HIGS for short) – against VdSCP41would enhance plant resistance to V. dahliae. If it does prove effective, this approach may eventually reduce the need for chemical pesticides to protect crop plants.