New Insights into Structure and Function of Ammonium Transporters (AMT) in Phaseolus vulgaris

Parviz Heidari ^1* Mostafa Ahmadizadeh ² Sadra Rezaee ¹ Markus Kuhlmann ³

• ¹ Shahrood University of Technology, Shahrood, Iran
• ² University of Hormozgan, BandarAbbas, Hormozgān, Iran
• ³ Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Lower Saxony, Germany

Ammonium and nitrogen are two important sources of inorganic nitrogen that are crucial for the growth and development of plants. The absorption and mobility of ammonium is managed by ammonium transporters (AMTs). In present study, eleven candidates of the AMT family were identified in the bean genome and further characterized. Phylogenetic analysis of the PvAMT family members and their orthologs separated them into two main subfamilies. Members of subfamily I possessed a single exon each, whereas members of subfamily II showed either three or four exons. Docking analysis revealed multiple interaction sites between PvAMTs and the PII protein, which serves as a crucial component of the nitrogen pathway in bacteria. In silico examination of posttranslational protein modifications in PvAMTs revealed that each family member displayed unique differences in the number of possible phosphorylation sites. In addition, the average number of phosphorylation sites in PvAMT subfamily I members was higher than subfamily II. The study of RNA-seq data disclosed that PvAMT genes display a degree of tissue-specific expression in the presence of abiotic stresses. PvAMTs co-expression network revealed a prevalence of genes related to membrane and transporter functions, as well as DNA binding and transcription factor activities. The expression pattern of PvAMT genes showed that during drought stress and soil salinity, the transcription level of these genes upregulated in shoot parts. PvAMT1 gene increased its expression by 45 and 31 times under drought and salinity stress, respectively, compared to normal conditions, while its expression was down-regulated in root tissues. Overall, the results indicated that PvAMTs are multifunctional proteins and are involved in the response to drought and salt stress in beans.