Nitrate Content and Expression of Putative Nitrate Transporter Genes in Lettuce Fertilized with Nitrogen Fertilizers

ABSTRACTNitrate accumulation in plants is influenced by environmental conditions and genetic variability. It is important to develop approaches that could be used to reduce nitrate levels in lettuce (Lactuca sativa L.) because nitrate accumulated in leaves can cause harmful health effects in humans. A greenhouse experiment was conducted to determine effects of ammonium nitrate or urea nitrogen on lettuce fresh weight, nitrate content, and characterization of nitrate transporter genes in lettuce. Head fresh weight in cultivars grown with the nitrogen fertilizers differed. All cultivars accumulated more nitrates with urea than with ammonium nitrate fertilizer. ‘Great Lakes’ had lower nitrate accumulation than other cultivars due to urea or ammonium nitrate treatment. Lettuce nitrate transporter genes LsNRT1 and LsNRT2 were detected and their expression level varied due to cultivar and leaf position. ‘Great Lakes’ had low mRNA levels of LsNRT1 and LsNRT2 in leaves compared to other cultivars. ‘Great Lakes’ c...