Characterization of secreted epidermal patterning factor peptides and ERECTA family receptors as regulators for root hair development in Arabidopsis thaliana.

This study investigated the role of secreted peptides and receptors in root hair development. The secreted peptides EPF1, EPF2, EPFL4, EPFL5, EPFL6, and EPFL9 and their putative receptors ERECTA (ER), ERECTA-LIKE1 (ERL1), ERL2, and TMM were found to mediate the development of the root hairs in Arabidopsis under control conditions and in response to nitrate deficiency. EPF2, EPFL4, EPFL5, and EPFL6 act as positive regulators of root hair density, whereas EPFL9 functions as a negative regulator for root hair density and root hair length. The receptor ERL2 was found to be a positive regulator of root hair density and ERL1 was found to be a positive regulator of both root hair density and root hair length. Nitrogen starvation caused a small and statistically insignificant increase in root hair density in wild type plants but led to significantly greater increases in root hair density in epf mutant genotypes. In contrast, the EPFL9 RNA interference (EPFL9i) line showed a significant decrease, indicating that EPF2, EPFL4, EPFL5 and EPFL6 act as negative regulators of root hair density in response to nitrate starvation, whereas EPFL9 functions as a positive regulator. Nitrate starvation also led to significant increases in root hair length in the wild type and in nine of the epf single, double and triple mutant lines but caused a significant decrease in the EPFL9i line. Analysis indicated that EPF2, EPFL4, EPFL5 are negative regulators, and EPFL9 is a positive regulator, of root hair length increase in response to nitrogen starvation. Our findings provide insight into the role of members of EPF secreted peptides and ER family receptors in regulating Arabidopsis root hair development. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-025-04600-2.