Starvation as a weapon in fungal-plant warfare

Fungal pathogens cause devastating diseases in staple crops and pose a tremendous threat to food security. Therefore, it is critical to understand the mechanisms of fungal attack and plant defense. Recent studies provide new insights into the role of nutrient manipulation for both plant and pathogen combatants. On the plant side, a defense signaling system has been discovered that provokes starvation during disease to limit access to carbohydrate by the head smut fungus Sporisorium reilianum. For pathogenic fungi, a novel class of effector proteins in the rice blast fungus Magnaporthe oryzae and other fungi has Nudix hydrolase activity to provoke phosphate limitation in host plants. This novel effector strategy impairs plant immunity, thus favoring pathogen proliferation and disease. Intriguing new work also demonstrates that the phytohormones strigolactone and methyl jasmonate influence phosphate and carbon metabolism in fungi. As discussed in this review, these examples illustrate the importance of nutrients in determining disease outcomes and also provide insights to potentially support crop protection.