Molecular Cloning and Expression Analysis of Auxilin-Like Gene StAL1 in Potato (Solanum tuberosum)

Auxilin is a J-domain-containing defense-related protein involved in clathrin-mediated endocytosis (CME) and acts on many organisms including yeast, Caenorhabditis elegans, Drosophila, Arabidopsis thaliana and rice. Auxilin regulates biological processes such as signal transduction, antibacterial defense, and stress resistance. To investigate the function of Auxilin gene in response to plant pathogen infection, the full-length of potato (Solanum tuberosum L.) Auxilin gene named StAL1 was cloned. Bioinformatics analysis of the gene revealed that StAL1 consists of 4828 bp, including a 4380 bp open reading frame that encodes a protein with 1443 amino acids. StAL1 is highly similar to Auxilin-like protein in potato and other Solanaceae species. Based on the qRT-PCR assays tissue expression pattern analysis revealed that StAL1 constitutively expressed in potato. StAL1 was induced by Ralstonia solanacearum species complex (RSSC) and up-regulated to varying extents by specific concentrations of exogenous phytohormones, including salicylic acid (SA), methyl jasmonate (MeJA) and abscisic acid (ABA). Examination of tissue localization suggested that StAL1 was primarily expressed in specific tissues (the phloem of the stem and leaf vascular systems). Furthermore, transient expression analysis showed the StAL1-GFP fusion protein was localized in the nucleus of Nicotiana benthamiana leaves cells. More importantly, auxilin is involved in plant immune response and disease resistance as an immune receptor binding protein. The results of the study should lay down the foundation for future research on the functional characterization of the Auxilin in potato plants.