Figure 8: A model for the age-dependent change of plant resistance to insect herbivores.

(a) During plant growth, the JA-regulated defense is highly active at juvenile stage but declines with age, while defense compounds accumulate constitutively, which supply the insect resistance continuously during plant growth. (b) The miR156-regulated SPL9 group proteins stabilize JAZs though direct binding to its N-terminal. The increased amount of SPL proteins in aged plant promotes JAZ accumulation, which in turn attenuates JA response.