Cloning and abiotic stress expression analysis of galactose-binding lectin (GBL) gene from mulberry arid its prokaryotic expression in E. coli

摘要

Galactose-binding lectins (GBLs) are a subdivision of jacalin-related lectins and known to perform an essential role in plant protective mechanisms against plant pathogens, fungi, and viruses. A cDNA sequence encoding GBL was cloned and the gene has an open reading frame (ORF) of 657 bp, encoding a protein of 219 amino acids. The protein is predicted to have a molecular weight and isoelectric point (pl) of 23.76 kDa and 6.29, respectively. GBL has a jacalin-type lectin domain and fits into the JRL superfamily. The evolutionary relationship of GBL revealed that the GBL from Morus multicaulis was firmly related to that of Morus rotundibila, Morus alba, Morus notabilis, Artocarpus integer, Artocarpus nitidus and Champedak (cgb). qRT-PCR analysis showed that the gene was expressed in all the tissues tested, leaf, and bud displaying the highest transcript levels. There was a general decrease in the mRNA transcript level under cold and salt stress as compared to the mRNA transcript level of the control. SDS-PAGE and western blot results showed that His-tagged fusion GBL protein was positively expressed in E. coli. In total, our findings disclosed the molecular basis for the signal transduction mechanisms when abiotic stress is induced in a mulberry tree.