| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Institute for Terrestrial Ecology, Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, PE17 2LS, England.
Dep. of Biological Sciences, Hatherly Laboratories, Prince of Wales Road, Exeter, EX4 4PS, England.
* Corresponding author.
ABSTRACT
Velvetgrass (Holcus lanatus L.), also known as Yorkshire fog grass, has evolved tolerance to high levels of arsenate, and this adaptation involves reduced accumulation of arsenate through the suppression of the high affinity phosphate-arsenate uptake system. To determine the role of P nutrition in arsenate tolerance, inhibition kinetics of arsenate influx by phosphate were determined. The concentration of inhibitor required to reduce maximum influx (Vmax) by 50%, K1, of phosphate inhibition of arsenate influx was 0.02 mol m–3 in both tolerant and nontolerant clones. This was compared with the concentration where influx is 50% of maximum, a Km, for arsenate influx of 0.6 mol m–3 for tolerants and 0.025 mol m–3 for nontolerants and, therefore, phosphate was much more effective at inhibiting arsenate influx in tolerant genotypes. The high affinity phosphate uptake system is inducible under low plant phosphate status, this increasing plant phosphate status should increase tolerance by decreasing arsenate influx. Root extension in arsenate solutions of tolerant and nontolerant tillers grown under differing phosphate nutritional regimes showed that indeed, increased plant P status increased the tolerance to arsenate of both tolerant and nontolerant clones. That plant P status increased tolerance again argues that P nutrition has a critical role in arsenate tolerance. To determine if short term flux and solution culture studies were relevant to As and P accumulation in soils, soil and plant material from a range of As contaminated sites were analyzed. As predicted from the short-term competition studies, P was accumulated preferentially to As in arsenate tolerant clones growing on mine spoil soils even when acid extractable arsenate in the soils was much greater than acid extractable phosphate. Though phosphate was much more efficient at competing with arsenate for uptake, plants growing on arsenate contaminated land still accumulated considerable amounts of As. Plants from the differing habitats showed large variation in plant phosphate status, pasture plants having much higher P levels than plants growing on the most contaminated mine spoil soils. The selectivity of the phosphate-arsenate uptake system for phosphate compared with arsenate, coupled with the suppression of this uptake system enabled tolerant clones of the grass velvetgrass to grow on soils that were highly contaminated with arsenate and deficient in phosphate.
This article has been cited by other articles:
|
|
 |
|
  Y.-G. ZHU, C.-N. GENG, Y.-P. TONG, S. E. SMITH, and F. A. SMITH Phosphate (Pi) and Arsenate Uptake by Two Wheat (Triticum aestivum) Cultivars and Their Doubled Haploid Lines Ann. Bot., September 1, 2006; 98(3): 631 - 636. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Gumaelius, B. Lahner, D. E. Salt, and J. A. Banks Arsenic Hyperaccumulation in Gametophytes of Pteris vittata. A New Model System for Analysis of Arsenic Hyperaccumulation Plant Physiology, October 1, 2004; 136(2): 3198 - 3208. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Knudson, T. Meikle, and T. H. DeLuca Role of Mycorrhizal Fungi and Phosphorus in the Arsenic Tolerance of Basin Wildrye J. Environ. Qual., November 1, 2003; 32(6): 2001 - 2006. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Wang, F.-J. Zhao, A. A. Meharg, A. Raab, J. Feldmann, and S. P. McGrath Mechanisms of Arsenic Hyperaccumulation in Pteris vittata. Uptake Kinetics, Interactions with Phosphate, and Arsenic Speciation Plant Physiology, November 1, 2002; 130(3): 1552 - 1561. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Sharples, A. A. Meharg, S. M. Chambers, and J. W.G. Cairney Mechanism of Arsenate Resistance in the Ericoid Mycorrhizal Fungus Hymenoscyphus ericae Plant Physiology, November 1, 2000; 124(3): 1327 - 1334. [Abstract] [Full Text]
|
|
|
|
|
|
I. J. Pickering, R. C. Prince, M. J. George, R. D. Smith, G. N. George, and D. E. Salt Reduction and Coordination of Arsenic in Indian Mustard Plant Physiology, April 1, 2000; 122(4): 1171 - 1178. [Abstract] [Full Text]
|
|
|
|
|
|
M. J. Abedin, J. Feldmann, and A. A. Meharg Uptake Kinetics of Arsenic Species in Rice Plants Plant Physiology, March 1, 2002; 128(3): 1120 - 1128. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Agronomy Journal | Crop Science | |||
| Journal of Natural Resources and Life Sciences Education |
Vadose Zone Journal | ||||
| Soil Science Society of America Journal | Journal of Plant Registrations | The Plant Genome | |||
