Organ Specificity and Light Regulation of NADH-Dependent Hydroxypyruvate Reductase Transcript Abundance.

By probing total RNA blots with an NADH-dependent hydroxypyruvate reductase (HPR) cDNA clone, we have found that HPR transcript abundance is highly regulated in developing cucumber (Cucumis sativus) seedlings. HPR transcript levels in light-grown seedlings are 50-fold more abundant in leaves and cotyledons than in roots. When 12-day light-grown seedlings are shifted to the dark for 4 days, the HPR transcript level in leaves drops 20-fold. Upon return of these dark-adapted plants to the light, HPR transcript levels rise to 50% of the previous light-grown level within 2 hours.