Comprehensive genomic identification and expression analysis of the nucleobase-ascorbate transporter (NAT) gene family in apple

Abstract

Nucleobase ascorbate transporters (NATs), also known as nucleobase:cation-symporter 2 (NCS2) proteins, belong to an evolutionarily widespread family of transport proteins. Because little is known about NAT genes in apple (Malus domestica), this papper screened GDR genome databases and identified 14 NATs in that species. Here, presented an overview of this gene family in apple, including structures, chromosome distribution and localization, phylogenies, and motifs. Phylogenetic and structure analyses showed that these genes could be assigned to three clusters. The 14 genes selected here displayed differential expression patterns in various tissues. Expression was very high for MdNAT12, MdNAT4, and MdNAT6 in the shoot tips, mature leaves, and young and mature fruits. MdNAT1 and MdNAT7 tended to show increased expression while the fruits were maturing. MdNAT6 proved responsive to both drought and salinity. Their transcript levels were generally up-regulated significantly during the fruit maturation process as well as in response to the imposition of drought or salt stress. Results suggest that members of this family function in tissue development, fruit maturation, and plant adaptations to adverse growing environments.