Figure 12.

Possible participation of ethylene, through CTR1, EIN2, and EIN3/EIL1, in the regulation of the Fe-, P-, and S-related genes considered in this study. Ethylene (ET) production is enhanced in Fe-, P-, and S-deficient roots. ET then acts in a signaling pathway which includes ET receptors (ET_R) and the CTR1 and EIN2 proteins. This latter one can act through the EIN3/EIL1 TFs (represented as EIN3 in the figure), which have been implicated in the regulation of the FIT, PHR1, WRKY75, and SLIM1 TFs controlling the activation of Fe-, P-, and S-related genes, like FRO2, IRT1, PAP17, PHT1;5, and SULTR1;1 (see text for details). Results in this work suggest that the EIN2 protein plays a key role in the regulation of the physiological responses to the three deficiencies and in the crosstalk between them. Moreover, the results support that TFs in addition to EIN3/EIL1, like ERF1 and other ERFs, could participate in the upregulation of Fe- and P-related genes (dotted lines). In red, ET-related TFs; in green, Fe-related TF and genes; in purple, P-related TFs and genes; in blue, S-related TF and gene. “ → ” promotion; “−∥” inhibition.