Interesting, reminds me of the reporter gene technique often used in genetic engineering. Genes that express green fluorescent protein (GFP), or other similar proteins, can be used as a "genetic logging." Basically if the tissue is glowing, you know your changes took.

I'm curious how much extra metabolic stress a particularly bright plant has to bear? Through genetic manipulation, and artificial selection, you could pressure the organism toward brightness. But I could imagine quickly running into some hard limit, where the plant's metabolism is taxed too heavily, and it can't survive.