Figure 2.

Salicylic acid and NHP at the nexus of the plant growth-defense balance. Major regulators of growth and development have synergistic and/or antagonistic relationships with SA and potentially with NHP. These include key plant hormones (auxin, brassinosteroid, gibberellin, cytokinin, and strigolactone) and the master regulatory kinase Target of Rapamycin (TOR). SA and potentially NHP could independently or synergistically impact various aspects of plant growth and development. In particular, SA has been shown to influence germination and apical hook development, pollen tip growth during floral development, root growth and patterning, shoot biomass accumulation, primary metabolism, and photosynthesis. Ultimately, levels and homeostasis between free bioactive SA/NHP and inactive storage forms (SAG/NHPG) allow plants to dynamically balance resources between growth and defense. Higher SA/NHP potentiates immune responses at the expense of growth, while lower SA/NHP promotes growth processes and modulates immunity. Created with BioRender.com.