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Abstract
A rapid-cycling base population of Brassica was used as a model system for investigating the effects of temperature on Se and S metabolism in an initial study. B. oleracea, plants were grown in growth chambers using nutrient solutions with temperatures ranging from 10 to30 C. The responses of total Se and S accumulation were similar but temperature dependent and tissue specific. In a second study, different ratios of SeO4/SO4 were applied to investigate Se effects on S metabolism. Plant fresh weight, S and SO4 accumulation were highest when plants were grown in medium with SeO4 to SO4 ratio of 1:250. The accumulation of Se was highest found when low amounts SeO4 were added to nutrient solutions without SO4. Glutathione peroxidase activity (GPx) and glucosinolates were measured and affected by Se status, as well. In the literature, SeO4 was suggested to regulate SO4 uptake and affect the expression of sulfate transporters. In a third study, cDNAs associated with 12 different sulfate transporter genes were isolated from B. oleracea grown under various SeO4/SO4 nutritional regimes. A semi-quantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR) method was used to show how different ratios of SeO4/SO4 impacted the expression of sulfate transporter genes. Gene expression from these different transporters showed tissue specificity and regulation dependent on SeO4/SO4 status.