Hydroxylates (-)-(4S)-limonene to (-)-trans-isopiperitenol, a precursor of (-)-menthol. No activity with (+)- or (-)-piperitone, (-)-isopiperitone and piperitenone. (4S)-limonene + O2 + reduced [NADPH--hemoprotein reductase] = (1S,6R)-isopiperitenol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] This gene is normally not expressed in wild type plants. Gamma irradiation induced probably a mutation in a regulatory gene, leading to the repression of the native limonene-6-hydroxylase and in the novel expression of this previously silent limonene-3-hydroxylase. Belongs to the cytochrome P450 family.