In Japan, possession of germinable cannabis seeds for cultivation purposes is subject to prosecution. Cannabis seeds are marketed after being treated to prevent germination (heated or crushed). Currently, forensic examination of cannabis seeds is conducted by cultivating the seeds after germination tests for several weeks and then performing morphological observation and chemical analysis on the true leaves. In this study, we attempted to construct a rapid and simple method for the identification of cannabis seeds by combining the color reaction using 2,3,5-Triphenyl-2H-tetrazolium Chloride (TTC), a reagent that discriminates between living and dead cells, and DNA testing using a commercially available simple kit.
The color reaction using TTC can determine the viability of peeled embryos within 20 min at 45 ℃ as previously reported. This method is effective for quickly determining whether a seed has been heat-treated or not. However, in the color reaction, a commercial health food seed that claimed to be unheated showed some coloration. This sample had been crushed to prevent germination and was easily identified as non-germinable by morphological examination. After the color reaction, the embryos could be directly used for DNA extraction without washing, and the DNA testing could be carried out in about 2 hours by following the instruction manual of the kit. By following the above procedure, it was possible to identify in one day whether a seed was a germinable cannabis or not, without the need to cultivate the plant. This method is expected to make a significant contribution to improving the efficiency of cannabis seed analysis.