Fig 4. The promotion of root hair development is more likely to be due to an increased capacity for water loss rather than an enhanced demand for phosphate.

(A) Two proposed models to explain the enhanced root development and phosphate accumulation observed in the epf1epf2 mutant. (Top) Increased water loss promotes root hair development. (Bottom) increased frequency of stomata incurs a phosphate cost which leads to phosphate stress and the subsequent promotion of root hairs. (B, Left) A relationship exists between conditions which reduce leaf boundary layer resistance and rooting length. The X axis denotes distance from a moving air source with 1 being the closest. (B, Right) Plants grown under identical conditions without the presence of a moving air source. A relationship between transpiration/stomatal density and rooting length exists. (C) Plants grown under phosphate limiting conditions display normal levels of stomatal density. Bars with no letters in common are significantly different, P<0.05, (Tukeys test after one-way ANOVA). Error bars represent SE.