sentences:  CHS is noncompetitively inhibited by flavanoid pathway products such as naringenin and chalcone naringenin.Despite lack of direct evidence "in vivo", flavonoids are believed to accumulate in the cytosol to a level that blocks CHS activity to avoid toxic levels in plants.CHS is constitutively expressed in plants but can also be subject to induced expression through light/ UV light and well as in response to pathogens, elicitors and wounding.