3.13.1.1 down the UDP-sulfoquinovose synthase in Solanum lycopersicum wild-type leaves is are downregulated during extended darkness, the expression of chloroplast-localized SQD1 transcript decreases during dark stress and recovers upon return to light in both wild-type and SO Ri plant. SQD1 transcript and protein levels are significantly up-regulated in response to sulfite injection into leaves of dark-stressed wild-type plants or into wild-type and SO Ri mutant leaves grown under a natural light regimes 726230 3.13.1.1 up SQD1 transcript and protein levels are significantly up-regulated in response to sulfite injection into leaves of dark-stressed wild-type plants or into wild-type and SO Ri mutant leaves grown under a natural light regimes 726230