A conserved gene regulatory network controls root epidermal cell patterning in superrosid species

center dot In superrosid species, root epidermal cells differentiate into root hair cells and nonhair cells. In some superrosids, the root hair cells and nonhair cells are distributed randomly (Type I pattern), and in others, they are arranged in a position-dependent manner (Type III pattern). The model plant Arabidopsis (Arabidopsis thaliana) adopts the Type III pattern, and the gene regulatory network (GRN) that controls this pattern has been defined. However, it is unclear whether the Type III pattern in other species is controlled by a similar GRN as in Arabidopsis, and it is not known how the different patterns evolved. center dot In this study, we analyzed superrosid species Rhodiola rosea, Boehmeria nivea, and Cucumis sativus for their root epidermal cell patterns. Combining phylogenetics, transcriptomics, and cross-species complementation, we analyzed homologs of the Arabidopsis patterning genes from these species. center dot We identified R. rosea and B. nivea as Type III species and C. sativus as Type I species. We discovered substantial similarities in structure, expression, and function of Arabidopsis patterning gene homologs in R. rosea and B. nivea, and major changes in C. sativus. center dot We propose that in superrosids, diverse Type III species inherited the patterning GRN from a common ancestor, whereas Type I species arose by mutations in multiple lineages.

Automated summary

By studying the wild plants Rhodiola rosea, Boehmeria nivea, and Cucumis sativus, it was found that R. rosea and B. nivea belong to the Type III root hair cell distribution pattern, while C. sativus belongs to the Type I pattern. There are significant similarities in the structure, expression, and function of Arabidopsis patterning gene homologs in R. rosea and B. nivea, while major changes were observed in C. sativus. It is proposed that different Type III species in superrosids inherited the patterning gene regulatory network from a common ancestor, while Type I species arose through mutations in multiple lineages.