Genome-wide classification and expression analysis of nucleobase–ascorbate transporter (NAT) gene family in tomato

Abstract

Ascorbic acid or vitamin C is a wide spectrum antioxidant and plays a crucial role in a many metal-containing enzymes essential for humans, which are unable to synthesize the vitamin C and must obtain it from dietary sources. Ascorbic acid is transported by sodium-coupled ascorbic acid transporters or SVCTs in humans. However, little information is available about the nucleobase–ascorbate transporters (NATs) in tomato (Solanum lycopersicum). In the current study, we identified 12 NAT genes by screening SGN genome databases in tomato. A complete overview of this gene family in tomato is presented, including gene structures, chromosome distribution and localization, phylogenies, motif analysis and expression profiles. The SlNAT genes contained 14 exons, mostly, and dispersed on all the chromosomes except chromosome 8 and 9. All the SlNATs were located to plasma membrane, chloroplast thylakoid membrane, Golgi body, and endoplasmic reticulum (membrane). The phylogenetic tree showed that the plant NATs were divided into 4 clades, well-supported by the distribution of conserved motifs, and the SlNAT proteins shared higher similarity and clustered more closely with AtNAT proteins. Furthermore, the expression profiles of SlNAT genes in various organs showed 9 out of 12 SlNAT genes were constituently expression with differential expression levels under normal growth conditions. Our systematic analysis will provide a useful platform for molecular clone and functional identification of NAT genes in tomato and probably other Solanaceae plants.