Root hair phenotypes in wild‐type (W115 (WT)) and PDR1 OE Petunia hybrida plants. Root hairs of 3‐wk‐old WT and PDR1 OE petunia plantlets grown on half‐strength MS agar plates. (a–c) Quantification of lateral root density, root hair density (area evaluated = 1.6 cm2) and root hair length in WT and PDR1 OE roots. (d, h) WT root segment: (d) differentiated (2 cm from the root tip); (h) above the root tip. (e, i) PDR1 OE root segment: (e) differentiated (2 cm from the root tip); (i) above the root tip. (f, j) WT lateral roots: (f) emerging; (j) elongated. (g, k) PDR1 OE lateral roots: (g) emerging; (k) elongated. In panels (a–k), the asterisk indicates the first root hair from the root tip. Bars, 400 μm. Values in (a–c) are means ± SE. *, P < 0.05.