Complementation and protein localization analyses of R3 MYBs in an mutant.

Root hairs play vital roles in plant growth since they enable the efficient absorption of water and nutrients from the soil. Recent advances in research have provided a deeper understanding of the molecular genetic mechanisms underlying root hair differentiation. () and its four homologs, which belong to the gene family and encode R3 MYB transcription factors, play central roles in root hair differentiation. In this study, to better understand the functional specificity and contribution of these five family genes, we conducted phenotypic and expression analyses of the CPC family proteins in a mutant background. As a result, () and were found to complement the hairless root phenotype of the mutant, as did , whereas () and did not rescue the phenotype. Protein expression analysis revealed that GFP fluorescence was nearly undetectable in and plants, supporting the incapability of root hair formation in these plants. Interestingly, the fluorescence intensity of the CPC:GFP fusion protein was weaker than that of ETC1:GFP and ETC3:GFP fusion proteins. These results were inconsistent with the result of the phenotypic analysis, in which the three genes promoted root hair formation to almost the same degree in the mutant background. We further discuss the discrepancy between the root hair phenotypes and the expression levels of CPC family proteins.