Shedding light on plant immunity: Light-regulated defense against P. infestans (PNAS)

While infection by pathogens and the reciprocal immune responses are well studied in plants, the influence of other abiotic factors on these processes is not very clear. In an attempt to understand the role of light on plant defense, Gao and colleagues have shown that the AVRvnt1 effector protein secreted by Phytophthora infestans gives rise to light-dependent responses mediated by the host protein Rpi-vnt1.1 in Solanum venturii. Further analyses have revealed that these responses depend on the interaction of AVRvnt1 with chloroplast-localized glycerate 3-kinase (GLYK), which requires an N-terminal transit peptide. Interestingly, the light dependency is conferred by the light-dependent alternative promoter selection (APS) of GLYK that produces a full-length, chloroplast-localized protein in the presence of light, but in prolonged darkness produces a truncated, cytosolic protein that doesn’t interact with AVRvnt1. Also, the effector protein subverts GLYK activity by interfering with its trafficking and enabling its degradation through proteasome. This work demonstrates that Rpi-vnt1.1–mediated disease resistance is light-dependent, shedding on the regulation of immune response to a commercially important crop pest. (Summary by Pavithran Narayanan @pavi_narayanan). Proc. Natl. Acad. Sci. USA.