Effect of phosphorus deficiency on the expression and protein localization of ENHANCER OF TRY AND CPC3 gene in Arabidopsis roots

Increased hair in Arabidopsis roots during phosphorus deficiency is an important adaptation mechanism. The CAPRICE (CPC) gene, along with its six homologs, plays a pivotal role in root hair formation. Our previous study indicated upregulated expression of ENHANCER OF TRY AND CPC1 (ETC1) and ENHANCER OF TRY AND CPC3 (ETC3) homologous genes in response to phosphorus deficiency. ETC1 translocates from the root sub-epidermis to epidermal cells, thereby increasing the number of root hairs. In this study, we specifically focused on ETC3 to explore its function in this process. Our results showed that etc1, etc3, and etc1 etc3 mutants did not induce as much root hairs in response to phosphorus deficiency as the wild type. The upregulation of ETC1 and ETC3 in response to phosphorus deficiency was restricted to the roots, with no such response observed in leaves. Furthermore, examination of ETC3:GFP protein localization revealed that ETC3 expression was induced in the internal root tissues under phosphorus deficiency, without migrating to epidermal cells as observed for ETC1. This finding suggests that ETC3 may indirectly contribute to root hair formation through a different mechanism. Therefore, elucidating the complex process that governs root hair increase in phosphorus-deficient plants can lead to future advances in plant breeding and nutrient stress adaptation.