Figure 5.

Model of SaARF4 including SaACO4 and ethylene under Cd stress in the LR developmental process: under normal conditions, auxin was evenly distributed in the roots (A); at the beginning of Cd stress, the production of ethylene was enhanced and promoted the process of local auxin accumulation (LAA). Then, the expression of SaARF4 was enhanced with auxin accumulation, which gradually repressed SaACO4 expression and finally inhibited ethylene production (B); the decline in ethylene production may be helpful for maintaining the auxin concentration at the sites of LAA, and this process may provide the auxin conditions for LR development (C).