Root hair abundance impacts cadmium accumulation in Arabidopsis thaliana shoots

Root hairs increase the contact area of roots with soil and thereby enhance the capacity for solute uptake. The strict hair/non-hair pattern of Arabidopsis thaliana can change with nutrient deficiency or exposure to toxic elements, which modify root hair density.

Details of the surface of primary roots
Details of the surface of primary roots (A–D) and sections with root hairs (E–H) of four Arabidopsis thaliana genotypes grown for 14 d in agar containing Murashige and Skoog (MS) medium. The genotype Columbia (Col-0), which has a distinct pattern of alternating root hair-forming and non-forming rhizodermal cells was used as a control (A, E). In the mutant wer/myb23, most epidermal cells develop hairs (B, F), whereas mutants rhd6-1 and cpc/tryare unable to form root hairs (C, D and G, H, respectively). Arrows indicate root hairs. Note the development of root hairs in the ‘H position’ facing the intercellular space between two underlying cortical cells in Col-0, whereas the mutant wer/myb23 forms root hairs in both the ‘H position’ and also outside a periclinal cortical cell wall, called the ‘N position’. Scale bars = 80 µm (A–D), 30 µm (E–H).

Kohanová et al. assess the effects of root hairs on cadmium (Cd) uptake and translocation by comparing the Arabidopsis thaliana ecotype Columbia (Col-0) with mutants lacking root hairs (rhd6-1, cpc/try) and a mutant in which most rhizodermal cells develop into hairs (wer/myb23). The results indicate that root hair density can have a large effect on Cd accumulation in shoots, suggesting that the symplasmic pathway might play a significant role in the uptake and accumulation of this toxic element.