Transcription factors MdEIL1 and MdHY5 integrate ethylene and light signaling to promote chlorophyll degradation in mature apple peels

Although it is well established that ethylene and light stimulate the process of chlorophyll degradation in mature apple peels, there is still a need for further exploration of the molecular mechanisms that regulate this process. This study identified <i>MdEIL1</i> and <i>MdHY5</i> as promoters of the chlorophyll degradation pathway in apple peels, activated by ethylene and light. Physiological and molecular tests demonstrated that MdEIL1 and MdHY5 are responsible for activating the expression of genes associated with chlorophyll degradation, including <i>MdERF17</i>, <i>MdNYC1</i>, <i>MdPPH</i>, and <i>MdPAO</i>. Furthermore, the interaction between MdEIL1 and MdHY5 proteins enhances their regulatory activity on the target gene <i>MdERF17</i>. Moreover, MdEIL1 binds to the promoter of <i>MdHY5</i>, resulting in the upregulation of its expression, which is further enhanced in the presence of the MdEIL1-MdHY5 protein complex. These findings indicate that MdEIL1-MdHY5 module acts as positive regulator mediating ethylene and light signals that promote chlorophyll degradation in apple peels.