Stimulation of root hair elongation in Arabidopsis thaliana by low phosphorus availability

Abstract

Low phosphorus availability stimulates root hair elongation in many plants, which may have adaptive .significance in soil pho.spliorus acquisition. We investigated Uie effect of low phosphorus on the elongation of Arahidopsis thaliana root hairs. Arabidopsis thaliana plants were grown in plant culture containing high (1000 mmol m"') or low (1 mniolm""') phosphorus concentrations, and root hair elongation was analysed by image analysis. After 15 d of growth, low-phosphorus plants developed root hairs averaging 0-9 mm in length while high-phosphorus plants of the same age developed root hairs averaging 0-3 mm in length. Increased root hair length in low-phosphorus plants was a result of both increa.sed growth duration and increased growth rate. Root hair length decreased logarithmically in response to increasing phosphorus concentration. Local changes in phosphorus availability influenced root hair growth regardless of the phosphorus status of the plant. Low phosphorus stimulated root hair elongation in the hairless axr2 mutant, exogenously applied lAA stimulated root hair elongation in wild-type high-phosphorus plants and the auxin antagonist CMPA inhibited root hair elongation in low-phosphorus plants. These results indicate that anxin may he involved in the low-phosphorus response in root hairs. auxin; phosphorus

The nutritional control of root development

“…Root hair production responds particularly strongly to P deficiency: when rape, spinach and tomato plants were grown at P i concentrations >100 µM, root hairs were infrequent and short, whereas at low P i (<10 µM) they were long and abundant (Foehse and Jungk, 1983). Similar effects have been reported in Arabidopsis seedlings grown in culture on high and low P i (Bates and Lynch, 1996).…”

“…In P-deficient Arabidopsis plants, both components of growth contributed to the increased length: the maximum rate elongation under low P was 67% higher than under high P and the duration of growth was increased from 5.5 to 8.25 h (Bates and Lynch, 1996). Thus at least three separate stages of root hair development in Arabidopsis are susceptible to regulation by the P supply.…”

“…In a developmental study with Arabidopsis seedlings it was found that the differences between root hair length in 'low P' and 'high P' plants did not show up until 6 days after germination, after which the newly developed root hairs became progressively longer in the 'low P' plants and progressively shorter in the 'high P' plants (Bates and Lynch, 1996). This would again seem to be most consistent with an effect of the internal P content of the seedlings rather than the external P concentration.…”

Arsenate (As) uptake by and distribution in two cultivars of winter wheat (Triticum aestivum L.)

“…High efficiency of P uptake by plants growing in soil can mainly be ascribed to (1) the mobilization of sparingly soluble P in the rhizosphere; (2) root architecture and the density of Pi transporters on root cell membranes; (3) symbiotic association with mycorrhizal (especially arbuscular mycorrhizal) fungi (Fö hse and Jungk, 1983;Bates and Lynch, 1996;Neumann et al, 2000;Zhu and Smith, 2001). However, in solution culture high P uptake efficiency can only depend on root architecture and the density of Pi transporters.…”

Method for evaluation of root hairs of common bean genotypes

“…Root hairs are subcellular extensions of the root epidermis that contribute to the acquisition of immobile nutrients such as phosphorus (Jungk, 2001). Root hair production is stimulated by the deficiency of several nutrients, including iron, zinc, manganese, and phosphorus, but, at least in Arabidopsis, phosphorus has a greater effect than other nutrients on root hair density and length (Bates & Lynch, 1996;Ma et al, 2001). Phosphorus mobility in soil is governed by diffusion rather than mass flow.…”