Recently, we found that the Arabidopsis TT19 protein, a glutathione S-transferase, has two functional domains that influence both anthocyanin and proanthocyanidin accumulation. To further understand the function of this protein in the other species, we cloned a cDNA encoding a glutathione S-transferase (namely CMGSTF12) from Camelina sativa, an oil crop that has received renewed interest due to its biofuel value and high omega-3 levels. Southern blot analysis demonstrated one copy of CMGSTF12 in C. sativa. Transformation of the Arabidopsis loss-of-function tt19-1 mutant with CMGSTF12 cDNA complemented accumulation of anthocyanin in vegetative tissues and resulted in the wild-type level of proanthocyanidin (both extractable and unextractable) in seeds. No obvious flavonoid accumulation changes were detected in the transgenic seeds, indicating that CMGSTF12 may only involve the lower flavonoid pathway, further proving that the TT19 protein controls accumulation of unextractable proanthocyanidin.