Understanding the role of MAKR6 in Arabidopsis thaliana L. root development

Motivation and Aim:The MEMBRANE-ASSOCIATED KINASE REGULATOR (MAKR) family is a recently discovered protein family, which includes seven members [1].Its constituent proteins are essential regulators of plant development.BKI1 and MAKR1 regulate brassinosteroid signaling.MAKR2, MAKR4 and MAKR5 control root gravitropism, lateral root formation, and formation of root protophloem respectively.At the same time, biological functions of the remaining paralog, MAKR6, are still unknown.Here we infer MAKR6 function based on the analysis of its expression pattern and the promoter analysis.Methods and Algorithms: We measured the overall expression level of MAKR6 using RT-qPCR.Using Agrobacterium-mediated transformation, we generated Arabidopsis thaliana reporter lines pMAKR6:nls3GFP, in which pMAKR6 promoter regulated green fluorescent protein (GFP) expression.To detect the reporter signal, we used epifluorescent and confocal microscopy techniques.The list of transcription factors (TFs) -potential regulators of MAKR6 expression -was compiled by superimposing the coordinates for MAKR6 promoter and publicly available DAP-seq peaks for 365 TFs [2].Results: We demonstrated that pMAKR6 promoter is active in above and below ground parts of A. thaliana seedlings with cell-type specificity.Using RT-qPCR, we demonstrated that MAKR6 is an early auxin response gene, which is upregulated after 30 minutes of auxin application.In the reporter line, auxin treatment enhanced GFP signal in both roots and shoots, and induced ectopic expression of GFP in the root differentiation zone.The potential binding regions for a number of known auxin response regulators (including ARF5) were found in pMAKR6 promoter.Conclusion: Taken together, our results evidence that MAKR6 might be a new auxin responsive regulator of plant development in A. thaliana.