Root hair formation capacity is associated with shoot growth under nutrient sufficiency and ETC3 induction under phosphate limitation in Arabidopsis

Abstract

Root hairs enhance nutrient uptake by increasing root surface area. CAPRICE (CPC) and its homolog ENHANCER OF TRY AND CPC1 (ETC1) are R3-type MYB transcription factors that regulate root hair differentiation in Arabidopsis thaliana . Here, we report observations from a three-genotype comparison in Arabidopsis thaliana – wild type (WT), the root-hair-defective cpc etc1 double mutant, and the root-hair-enhanced CPC::CPC – grown hydroponically under nutrient-sufficient and deficient nitrogen (N), phosphorus (P) or potassium (K) conditions. Under nutrient-sufficient conditions, CPC::CPC exhibited increased leaf fresh weight and delayed bolting, relative to WT, accompanied by a higher leaf number. cpc etc1 also showed greater leaf fresh weight, attributable to increased weight per leaf. Flowering-related transcripts ( FT , CO , SOC1 ) showed no significant differences between WT and CPC::CPC . Under nutrient-deficient conditions, root hair number increased in WT under Low P and Low K, while CPC::CPC increased under Low P only; cpc etc1 remained low across conditions. At the transcriptional level, among CPC-family genes assayed in WT roots, expression of the CPC homolog ETC3 was upregulated under Low P, whereas CPC , ETC1 and TRY were not significantly altered. These results indicate that intrinsic root-hair formation capacity is associated with shoot growth and developmental timing under nutrient sufficiency and that phosphate limitation elicits a characteristic root hair response with selective ETC3 induction. These findings provide compact evidence linking epidermal cell-fate capacity to whole-plant traits and nutrient-responsive transcription.