Genome-wide identification, in-silico characterisation and expression analysis of multiprotein bridging factor 1 gene family members in rice

Abstract

The multiprotein bridging factor 1 (MBF1) proteins are evolutionarily conserved transcription co-factors. However, little is known about rice MBF1 gene family and its role. A genome-wide search led to the identification of two MBF1 genes in the rice genome. Their proteins contained characteristic MBF1 and helix-turn-helix domains. Phylogenetic analysis showed that they belong to two different groups. Exploration of publicly available rice transcriptome data revealed that OsMBF1b exhibits constitutively high transcript abundance in all tissues and developmental stages of rice with a little alteration in its expression. Contrarily, OsMBF1c exhibited a prominent alteration in its expression in response to environmental perturbations. Both OsMBF1s showed the highest expression in endosperm. Analysis of publicly-available rice transcriptome data also showed that both OsMBF1s have a role in response to different stresses, especially in heat. Transcript analysis using qRT-PCR confirmed heat inducibility of OsMBF1c in contrasting genotypes i.e. IR64 (heat sensitive) and Nagina 22 (heat tolerant). qRT-PCR also confirmed the drought inducibility of both genes in the IR64 genotype which is sensitive to drought stress also as revealed by analysis of different parameters. In-silico interaction study also indicated their role in heat response as a number of proteins required to cope with high temperatures were predicated to be their interacting partners. Several heat-responsive genes were found to co-express with OsMBF1s. In-silico promoter analysis revealed the occurrence of stress-responsive elements in their putative promoters. Interestingly, both OsMBF1s showed diurnal rhythmic expressions having peaks during the daytime when the temperature rises. Altogether, this study indicates an active role of OsMBF1s in thermotolerance in rice. This is the first report regarding the characterization of rice MBF1 members.