Figure 4.

Hypothetical model of the potential polyamines- (PAs-) based responses of citrus plants against viral diseases. (a) Integration of PAs with seven phytohormone pathways in citrus response to the infection with Citrus tristeza virus (CTV), and (b) The interaction between PAs, auxins, cytokinins (CKs), and methyl jasmonates (meJA) during the CTV infection. Solid lines with arrowhead signify positive reaction, dashed lines with blunt-heads indicate negative interaction, while round-dotted lines with arrows represent hypothetical mechanisms or uncharacterized elements. For more details and abbreviations, see the main text.