Cloning and functional analysis of NcTWD1 in Neolamarckia cadamba (Roxb.) Bosser

Auxin is a key phytohormone that orchestrates diverse processes in plant growth and development. Twisted dwarf 1 (TWD1) is known to facilitate the folding and functional maturation of auxin transporter proteins within the secretory pathway. In this study, a homolog of Arabidopsis thaliana (L.) Heynh AtTWD1 was identified and cloned from Neolamarckia cadamba (Roxb.) Bosser using integrated bioinformatics and molecular approaches, designated NcTWD1. Results indicated that the NcTWD1 sequence was 1 098 bp in length, encoding a 365-amino acid protein. Structural modeling indicated that NcTWD1 and AtTWD1 share highly similar tertiary conformations, each containing an FKBP domain, a TRP domain, and a C-terminal membrane-anchoring domain. RT-qPCR analysis demonstrated that NcTWD1 is expressed across multiple tissues, including roots, stems, shoot tips, young leaves, mature leaves, petioles, and seedlings. Subcellular localization revealed predominant accumulation of NcTWD1 within the endoplasmic reticulum. Overexpression of NcTWD1 in the A. thaliana twd1-4 mutant rescued its characteristic dwarf and twisted phenotypes. Co-immunoprecipitation assays further confirmed a physical interaction between NcTWD1 and the auxin transporter NcABCB1 in N. cadamba, indicating that NcTWD1 likely performs a conserved regulatory role analogous to AtTWD1 in A. thaliana.