MBF1s regulate ABA-dependent germination of Arabidopsis seeds.

Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) controls gene expression by connecting transcription factors and the basal transcription machinery. In Arabidopsis thaliana functions of MBF1 genes have been related to stress tolerance and developmental alterations. Endogenous ABA plays a major role in the regulation of Arabidopsis seed dormancy and germination.

The analysis of an Arabidopsis triple knock-down mutant reveals functions for MBF1 genes under oxidative stress conditions.

Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) type belong to a small multigenic family that controls gene expression by connecting transcription factors and the basal transcription machinery. In this report, a triple knock-down mutant (abc-) for the Arabidopsis thaliana MBF1 genes AtMBF1a, AtMBF1b and AtMBF1c was generated. The phenotypic characterization using oxidative agents such as hydrogen peroxide and methyl viologen revealed that the abc- mutant was more sensitive to oxidative stress.

The potato transcriptional co-activator StMBF1 is up-regulated in response to oxidative stress and interacts with the TATA-box binding protein.

To gain a better understanding on the function of the potato Solanum tuberosum Multiprotein Bridging Factor 1 protein (StMBF1) its interaction with the TATA box binding protein (TBP) was demonstrated. In addition we reported that StMBF1 rescues the yeast mbf1 mutant phenotype, indicating its role as a plant co-activator. These data reinforce the hypothesis that MBF1 function is also conserved among non closely related plant species.