Whole-genome resequencing of Arabidopsis mutant n83

Plant amino acid transporters play important roles in amino acid uptake, distribution, storage and stress response. Narciclasine (NCS), a natural bioactive compound, plays a significant role in regulating plant growth and exhibiting anticancer properties. However, its mechanism of regulating plant growth is still unclear. In this study, we report an Arabidopsis mutant, n83, which exhibits significantly reduced sensitivity to NCS compared to the wild type. Map-based cloning, genome resequencing and T-DNA mutant verification revealed that the reduced NCS sensitivity in n83 is caused by a point mutation at the 2561st base of Lysine-Histidine Transporter4 (LHT4), resulting in a G490R amino acid substitution. Additionally, overexpression of LHT4 markedly increased Arabidopsis sensitivity to NCS. Heterologous expression of LHT4 in yeast significantly inhibited the growth of the yeast strain. However, this inhibition disappeared when Gly490 was mutated to other neutral, acidic, or basic amino acids. In conclusion, our results demonstrate that LHT4 mediates the transmembrane transport of NCS, and the glycine residue at position 490 is critical for the transport function of LHT4.