关键词: 桃, 镁, 镁离子转运蛋白, 基因表达, 功能分化

Abstract: To investigate the roles of magnesium transporters（MGTs）in magnesium transportation，the genome-wide identification of peach（Prunus persica）MGTs（PpMGTs）was performed and their effects in exogenous magnesium application on peach tree were studied. A total of eight PpMGTs，which were unevenly distributed in four chromosomes（Chr1，Chr3，Chr6 and Chr8），were identified based on protein homology searches and conserved domain analyses. System evolution analysis results suggested that plant MGTs could be grouped into five different clades which show quantitative differences in species-specific MGTs. PpMGTs had 4–13 exons，ten conserved motifs in protein sequence，and diverse cis-elements of stress response，transcriptional regulation，circadian rhythm，phytohormone response and developmental growth in their upstream promoters. All PpMGTs were transcribed in flowers，fruits，leaves and roots with their unique tissue specific expression pattern. The distinct transcriptional changes of PpMGTs could be observed after exogenous magnesium spraying. Differentially expressed genes found before and after exogenous magnesium application were discrepant in peach leaves and peels，but some of them were commonly involved in the photosynthesis pathway. The transcriptional profile and correlation analysis results suggested that expressional changes of light-harvesting chlorophyll a/b protein complex genes were positively corelated with transcriptional levels of PpMGT4，PpMGT6 and PpMGT8. Heterologous expression of PpMGT4，PpMGT6 and PpMGT8 were able to rescue growth defects of magnesium transport mutant MM281（Salmonella typhimurium mutant），suggesting these three proteins were serving important magnesium transport functions. Thus，the results from sequence characteristics，expressional profiles and exogenous magnesium application showed that PpMGTs had potential functional diversity and synergistic effects in magnesium transport and utilization. The expressional changes of PpMGT4，PpMGT6 and PpMGT8 may associate with exogenous magnesium intake and magnesium utilization.

Key words: Prunus persica, Mg, MGT, gene expression, functional diversity