Effect of genotype and growing season on nitrate accumulation and expression patterns of nitrate transporter genes in potato (Solanum tuberosum L.)

Nitrate (NO₃^?) is the most important source of mineral nitrogen (N) affecting the vegetative growth, the tuber yield and the quality of potato (Solanum tuberosum L.). The screening of 16 potato cultivars for low nitrate content was reported and the effects of genotype and experimental factors on nitrate accumulation were studied. Both genotype and growing season had a highly significant effect on dry weight, number of tubers/plant, yield and nitrate accumulation in potato which varied significantly from one genotype to another. Furthermore, nitrate accumulation varies with the season, being higher in the first season (autumn) than in the second season (spring), for all the genotypes. The cultivars Safrane and Universa followed by Actrice and Alaska produced the highest tuber yield/plant during the first and second season, respectively, accumulating higher quantities of nitrate compared to other cultivars. Ponomera cultivar was of interest from a breeding perspective due to both combining best tuber yield/plant and low nitrate accumulation for both growing season. Expression pattern of nitrate transporter genes (StNRT1.2, StNRT1.5 and StNRT2.1) has been reported. Thus, these genes were differentially expressed which could be explained in part by the difference in nitrate accumulation rate between the studied cultivars. The results showed that high accumulator genotype got significant higher expression level of StNRT1.2, StNRT1.5 or StNRT2.1 which lead to the higher nitrate uptake rate and consequently higher nitrate accumulation than low accumulator genotype.