Molecular cloning and characterization of a novel basic helix–loop–helix-144 (bHLH144)-like transcription factor from Morus alba (L.)

Abstract

Basic helix–loop–helix (bHLH) transcription factors (TFs) are associated with many biological processes, including abiotic stress response in plants. With an objective to prospect novel drought stress responsive bHLH gene/s from mulberry (Morus alba L.), a woody perennial tree, we isolated 1512bp of bHLH-like gene, and its transcript variant of 1419bp by PCR-based approach using cDNA generated from leaf tissue. Since, the cloned sequences showed identity with Prunus mume bHLH144-like transcript, as per the BLASTn analysis, the variants are designated as MabHLH144a-like and MabHLH144b-like genes. The full-length MabHLH144a- and b-like cDNAs have 726bp open reading frames and the gene is predicted to encode a protein of 241 amino acids. The genomic clone of MabHLH144-like has 2304bp consisting of a single 786bp intron at the 5′ UTR region. Fold-Index analysis predicted that MabHLH144-like is highly disordered protein, a characteristic feature of TFs, and the expression analysis indicated that the transcript variants are differentially expressed in diverse tissue types and also under different abiotic stresses. Analysis of the possible miRNA binding sites revealed the absence of a target site in one the transcript variants, which would have contributed for the observed differential expression. As per our knowledge, this is the first report on cloning, and characterization of bHLH144-like gene and its transcript variant from mulberry.