For every reaction there is a creation.
Oxidase comes in many forms, some of which utilise free Oxygen molecules as in the case of ACC Oxidase which i think is the main point of focus here, some catalyze the oxidation of monoamines as in those we find regulating the Mitochondria, others also exist of course.
They are part of the donor and exchange system if you will, and are in many ways responsible for the process which leads to senescence (plants aging), but also in the process of maintaining cell integrity/ function through life as with say L-Monoamine.
I think in this case you are primarily referring to Aminocyclopropanecarboxylate oxidase eg ACC. Do plants encode genes for the production of oxidase, yes :) They are essential for cell function, but also for the initiation of decomposition as in the case of ACC and ETR-1 which leads to leaves falling off trees for example. ACC Oxidase is a transcription for the increased production of Ethylene (ETR-1).
You might see this as the management of radicals or not and the nature of time and energy. At the end of plants growth cycle, we see increased accumulation of such oxidase as a precursor to ethylene which initiates the degrading of the cells and so weakens the structure and integrity, killing the plant in such a way that it might be recycled to support future growth.
Does the cell have some in built timer from which it releases such reductive agents? Yes i suspect so, it is integral to the DNA.
Are Oxidase reactions up-regulated by microbial interactions, yes most likely too. For example, I can use microbial enzymes and nucleiods to reduce the impacts of oxidase, as in the case of the accumulation of ETR-1 receptors as plants age or are stressed by factors. I can use a secretion of a cyanbac, called ADH-1 to reduce the transcription of ETR-1, thus i can use this as a fruit wash, to preserve the shelf life of picked and harvested fruits. I can for example, use this in MJ to reduce the oxidative impacts on THC or CBD, allowing the retention of the compounds in non degraded forms for longer periods.
For me the use of mitigating enzymes which can then be used to delay the onset of ripening, or indeed induce it, is day to day now. Anyone growing with K+AMINO will be doing the same, using ADH-1 as an example
This is K+AMINO mate :)