Figure 10.

A Model of Ethylene Signaling Regulation of the Freezing Stress Response in Arabidopsis.

Cold stress rapidly inhibits ethylene production and downregulates EIN2 and EIN3/EIL1. The EIN3/EIL1 proteins, in turn, suppress the expression of CBF1-CBF3 genes and type-A ARR genes (ARR5, -7, and -15) by directly binding to their promoters. Therefore, type-A ARRs serve as mediators in the responses to ethylene and cytokinin signals to positively regulate freezing stress responses. On the other hand, cold slowly promotes EIN3 protein accumulation. Solid and dotted lines indicate direct and indirect regulation, respectively.