Genome-wide identification of 12 amino acid transporter families and molecular characterization of their transcriptional responses to various nutrient stresses in allotetraploid rapeseed

Background: Brassica napus is an important oil crop in China and has a great demand for nitrogen. Amino acid transporters (AAT) play a key role in amino acid absorption and transport in plants. However, the AAT family genes have not been reported in Brassica napus so far. Results: : In this study, genome-wide analysis identified 203 AAT members in Brassica napus genome. Based on phylogenetic and synteny analysis, BnaAATs were classified into twelve groups. The members in the same subgroups showed that similar physiochemical characteristics, intron/exon and motif patterns. By evaluating cis -acting regulatory elements (CREs) in the promoters, we identified some cis -acting regulatory elements (CREs) related to hormone, stresses and plant development. Darwin’s evolutionary analysis indicated that BnaAATs might have experienced strong purifying selection pressure. The BnaAAT gene family in Brassica napus may have undergone gene expansion, the chromosomal location of BnaAATs indicated that whole genome replication or segmental replication may play a major driving role. Differential expression pattern of BnaAATs under nitrate limitation, phosphate shortage, potassium shortage, boron stress, boron toxicity, cadmium toxicity, ammonium excess, and salt stress conditions indicated that they were responsive to different nutrient stresses. Conclusions: : In summary, these findings provide a comprehensive survey of the BnaAAT genes family and lay a foundation for the further functional analysis of family members. Transcriptome analysis identified genes that responded to stresses, which laid a foundation for the genetic improvement in rapeseed nutrient stress resistance.