Genetically altered Arabdopsis Thaliana plant, with green fluorescent protein (GFP) inserted near the on/off
switches for anoxia and drought genes. Cells expressing those genes glow green under a blue light (as shown).

A group of University of Tennessee plant scientists has genetically modified tobacco plants so that the plants will give off a phosphorescent green “glow” when plant immune systems are under stress – as might be caused by plant pathogens, drought, insects, etc. (The stress-indicating fluorescent proteins can be detected by scientific instruments only, as pictured above.) To implement this on a commercial basis, it is hypothesized, farmers would scatter the day-glow plants amidst a far greater number of normal plants, each GM plant serving as an attack sentinel for the surrounding a crop zone…

It is unclear how exactly how pest- or pathogen-specific the glow response could be made to be? There could be a problem with false positives, obviously, if other stressors also evoked the glow response.

The shortcomings of schemes such as this inevitably arise from basic material handling, inventory, and maintenance issues out in the field. And, as pointed out in the source article in Glowing crops could minimize pesticide use, it is hard to imagine poor farmers of developing nations being able to afford the sentinel plants. To say nothing of buying and maintaining the instrumentation needed to sense and record sentinel plant status and then choose the right dose of a specific pesticide which may or may not be immediately on hand!

How weird can it get?
Might we anticipate no smoking zones surrounded by glow-detecting instruments that set off alarms should anyone light up?

A snippet from the SciDev,net story:

Scientists have genetically engineered the natural immune system of the tobacco plant to make it change colour or glow in the presence of viruses, bacteria and other pathogens known to reduce crop yields, which normally force farmers to apply costly pesticides.

In laboratory tests, these ‘photosensory’ plants turn red or produce a fluorescent glow when infected.

Image and caption credit:NASA Marshall Space Flight Center Collection