I came across this news about the development of genetically re-engineered plants which can apparently detect explosives, other chemicals, pollutants, etc.
Dr. June Medford’s lab at the Colorado state University have re-engineered chlorophyll circuitry such that on exposure to a particular inducer the chlorophyll stocks are degraded and the biosynthesis of new chlorophyll is blocked. Thus the plants turn white within a time period of 24-48 hours after exposure. These plants can also reset themselves back to normal color when the inducer is removed. Also, another amazing observation was that the plants turned faster in presence of light than in darkness. They discuss this work in their 2006 paper - “A synthetic de-greening gene circuit provides a reporting system that is remotely detectable and has a re-set capacity”.
This is an amazing idea, considering its implications in security and pollution detection. Although, they are not exactly bomb-detector-plants considering the fact that it requires 24-48 hours to show visible color change. But on the contrary, the changes in the chlorophyll content is quite rapid (about 2 hours) and can be detected using any hand-held fluorescence detectors or even satellites.
These plants currently respond to a steroidal drug (inducer) - 4 hydroxytamoxifen (OHT). They obviously need to be genetically modified such that they respond to a stimuli of interest (Biologicals/chemicals/Pollutants). Although I do not understand how these plants are going to detect these chemicals from their surroundings, since in the studies conducted here, the inducer was added to the growth medium. There might have been some further work done in this topic since 2006 (but I couldn’t find any other papers regarding this work from their lab).
Apart from the science stuff, the other interesting part about all this news is what took the Homeland security or the military so long to look into this research?