Unlike ibi1-1 plants, SA non-accumulating NahG voz1/2-2 plants still expressed a residual level of BABA-IR against Hpa (Figure 4B), indicating activity of additional VOZ1/2- and SA-independent defense layers, which act at different stages of infection than relatively early callose-associated defense and relatively late SA-dependent defense, respectively. This evidence concerns the gene HPSE and infection.