Involved in light signaling, mainly phyA-mediated photomorphogenesis and in the integration of various phytohormone signals to modulate various aspects of plant development by affecting glutathione pools. In vitro, possesses glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene (CDNB) and benzyl isothiocyanate (BITC). glutathione + RX = a halide anion + an S-substituted glutathione + H(+) By dehydration stress, auxin, abscisic acid (ABA), jasmonate, ozone and transition from dark to far-red and red light. Delayed flowering, long-hypocotyl phenotype under low fluences of far-red light and insensitive to ABA-mediated inhibition of root elongation. Belongs to the GST superfamily. Tau family.