Fig. 8
Proposed schema for the role of spermidine (Spd) in coordinating the seed germination of sweet corn. Spd increased gibberellins (GA) contents in sweet corn seeds might through improving GA biosynthetic genes expressions and depressing GA catabolic gene expression respectively. Spd decreased abscisic acid (ABA) contents in sweet corn seeds might through the depression of ABA-synthetic genes expressions. Spd also affected ethylene homeostasis by activating the expression of ZmACS. In addition, an increase of H2O2 content in Spd-treated seeds was found, which associated with the endosperm cap weakening and embryo elongation growth. H2O2 could also induce a decrease in ABA and an increase in ethylene directly or indirectly to accelerate the germination process [8]