Final answer:
The alternative oxidase (AOX) of plant cells is likely activated by post-translational modification through protein phosphorylation, a process adding a phosphate group to proteins, which is integral to plant stress responses and redox proteomics.
Step-by-step explanation:
The post-translational modification that activates the alternative oxidase (AOX) of plant cells is likely to be protein phosphorylation. Protein phosphorylation involves the addition of a phosphate group to a protein molecule, typically catalyzed by a specific enzyme known as a kinase. Conversely, the removal of a phosphate group, termed dephosphorylation, is catalyzed by a phosphatase. These reversible modifications can significantly affect a protein's function and are a common regulatory mechanism in signal transduction pathways. Phosphorylation is implicated in various cellular processes and stress responses, including the mitigation of oxidative stress in plants. In the context of plant redox proteomics, identifying changes in phosphorylation status under stress conditions, such as waterlogging, is essential for understanding how plants adapt and respond to environmental challenges.