Identification of Differentially Expressed Putative Nitrate Transporter Genes in Lettuce

ABSTRACT

Nitrogen is important to plant growth and development, with nitrate being the major form absorbed by crops. Lettuce (Lactuca sativa L.) accumulates high levels of nitrate, which can cause harmful health effects in humans. Information is needed regarding accumulation of nitrate among lettuce genotypes. The lettuce cvs. Vitalia (type Butterhead); Great Lakes (type Iceberg); L01 (type Iceberg), and L02 (type Romaine) were used to determine expression patterns of nitrate transporter gene LsNRT in the cultivars and in nitrate accumulation. A computer modeling analysis indicated that genes LsNRT1 and LsNRT2 encode for low- and high-affinity nitrate transport, respectively, in lettuce. To better characterize nitrate transport in lettuce, the relative expression of these genes encoding nitrate transport was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). Higher nitrate accumulator cultivars posses higher nitrate transporter transcripts than low accumulators, indicating stronger ability to assimilate absorbed nitrate in the higher than the low accumulator. Increased knowledge of gene systems and identification of genotypes with low nitrate concentrations can be used in breeding programs.

KEYWORDS:

• Lactuca sativa
• breeding
• gene expression analysis
• low accumulator genotypes
• nitrate accumulation

Funding

The authors thank the Agricultural Research and Higher Education Institution (IRESA) and the Horticultural Sciences Laboratory (LR13AGR01) for financial support that made this project possible.