Genome-Wide Identification of NRT Gene Family and Expression Analysis of Nitrate Transporters in Response to Salt Stress in Poncirus trifoliata .

The uptake and transportation of nitrate play a crucial role in plant growth and development. These processes mostly depend on nitrate transporters (NRT), which guarantee the supplement of nutrition in the plant. In this study, genes encoding NRT with Major Facilitator Superfamily (MFS) domain were identified in trifoliate orange ( Poncirus trifoliata (L.) Raf.). Totally, 56 NRT1s , 6 NRT2s , and 2 NAR2s were explored. The bioinformation analysis, including protein characteristics, conserved domain, motif, phylogenetic relationship, cis -acting element, and synteny correlation, indicated the evolutionary conservation and functional diversity of NRT genes. Additionally, expression profiles of PtrNRTs in different tissues demonstrated that NRT genes possessed spatio-temporal expression specificity. Further, the salt condition was certified to induce the expression of some NRT members, like PtrNPF2.1 , PtrNPF7.4 , and PtrNAR2.1 , proposing the potential role of these NRTs in salt stress response. The identification of NRT genes and the expression pattern analysis in various tissues and salt stress lay a foundation for future research between nitrogen transport and salt resistance in P. trifoliata .